Archives of an email list on the history of binoculars. http://home.europa.com/~telscope/listpr50.txt home page: http://home.europa.com/~telscope/binotele.htm 50-100 ================================= Binocular List #50: 3/7/99. Zeiss numbering & trademark, Aluminum restoration, Teleater variation ===================================== Subject: Early Zeiss binocular serial numbers From: Fred Watson I read your piece in Binocular List #49 with great interest. Your list of serial numbers and Larry's production figures are both most illuminating. A few comments, together with the serial numbers under 250000 in my collection, as you requested: 1. The point that early serial numbers are model-specific has also been made by Larry in his 1990 ZH article, and by Hans Seeger in his `Feldstecher'. 2. John Gould noted some early serial numbers (including an 8x20 with the enviable S/N of 3!) in his 1986 ZH article. 3. I know Hans has been an avid collector of early Zeiss serial numbers for some time, so he may already have the answer to your question. My early serial numbers are: 8x20 Feldstecher: flat top, no ipd scale, signed in script, S/N 1634; 12x25 Feldstecher: sloping top, ipd scale, signed in script, S/N 9481; 5+10x Marine-Glas mit Revolver: ipd scale, signed in script, S/N 117. I don't think these add much to the debate, as they're all within the known envelopes. (I have two other Zeiss glasses with low serial numbers---a Fernglas 08 Galilean, and a Zeiss (London) British Army No.3 prismatic, both of 1916---but these are clearly not relevant to the present discussion.) Fred ========================= Subject: Zeiss lens trademark From: Lngubas@___m In conversation with my source in Jena, the Zeiss archivist - Dr. Wimmer. He says that although the trademark with the lens cell was approved in 1903 - it was not used until 1906. Well, he has the records to prove it. Larry Gubas =============================== Subject: Restoring aluminum From: "R.F.Bolton" In my work I have had to refurbish underwater camera housings that have been made from alluminium. The cause of the corrosion would obviously be salt water and the damage could be quite bad. The best method I have tried to date has been to have the surface 'glass bead blasted' rather than 'grit blasted'. This leaves a much smoother, but not glass smooth, surface than grit blasting. It will remove all traces of corrosion without removing lots of metal. I have then had the housings anodised rather than powder coated [painted] as it gives a more lasting finish for use in salt water. Also I have found a powder coated paint finish will 'lift' allowing water to pass between it and the housing causing a leak. For the binoculars in question a powder coat paint finish in an appropriate colour may be all that is required. Rod Bolton. Brisbane Photographic Repairs. PO Box 698. Kenmore. Brisbane, 4069, Australia. ------ (Another collector told me that after exposure to salt air, you have to neutralize salt, then you can use black anodizing, which is applied like cold blue for steel.) --Peter ==================================== Subject: gyro stabilized binoculars From: "R.F.Bolton" http://www.tiac.net/users/lanint/gyro.html (16x40 Russian gyro stabilized binoculars) I found the above site while looking for other things, maybe its of interest to you? Rod. ============================= Subject: Teleater variation Bill Beacom bought an unmarked glass that looks like the Perkeo on p47, Seeger, Feldstecher. It's IF, unlike most Teleater clones that use moving objectives to focus. He took it apart, and the prisms are like Seeger p132, lower row, (a), used by Schuetz, Ross, Zeiss; but these are cemented similarly to a Porro II. Bill's glass has a cover plate that is heart shaped, without the longer horizontal lobe of the Teleater, and the top corner comes to a point. I've seen that prism design in books, it's standard although I don't know the name, a different way of making a Porro II, both of which are a 'rearrangement' of the Porro I, by cutting the prisms in half & fusing two pieces. --Peter =================================== ======================================== Binocular List #51: 3/13/98. Steinheil, collimator, comparisons ========================================== Subject: Steinheil adjustment for image rotation Jim Rose is repairing a binocular with a very unusual & useful design that permits adjustment of image rotation while the binocular is assembled. The glass is marked Steinheil, Munchen, 8 x 30, 87369 VL, and has coated optics. Inside, there are four light shields, similar to those that are commonly found covering the reflecting sides of the prism. These are curved, not flat sheet metal like most, and at the base (the hypotenuse of the prism, at the edge where it meets the reflecting face) is a socket that engages a screw that passes through the body of the binocular, so the screw can be moved from the outside of the assembled binocular. The screw head has a groove cut in its circumference that engages a slot in the body of the binocular, about one half inch long, parallel to the housing covers. The screw therefore can move side to side and force the prism to rotate, which in turn causes the image to rotate. The leather cover of the binocular must be removed before the screw is visible. I know of no other binocular with a provision for adjustment of image rotation beyond simple moving of the prism in its seat, and would like to learn of other models that allow this. --Peter ======================= Subject: Binocular collimators From: "R.F.Bolton" I am making some progress on the collimator I am building but as I was working on the zero telescopes the thought came to me that in all the info I have managed to find on the subject of collimating, nowhere does it say what distance the binoculars being collimated, should be focussed at. Would any list member be able to give some advise regarding this? Is there an optimum setting or is infinity/long distance as good as any? Rod Bolton. ====================== From: Fan Tao Subject: Review of Burris 8x40 Fullfield, Celestron 9.5x44 ED, Swift 8.5x44 ED Recently I acquired a Burris 8x40 Fullfield and a Swift Audubon 8.5x44 ED. I have a Celestron 9.5x44 ED which invites comparison to the Swift, so I'll review it also. These are all porro prism binoculars with Japanese optics. I'll start with the Burris. Burris is a company which seems to cater mainly to hunters, so I haven't been that familiar with their binoculars. Their Fullfield line of binoculars (which include 7x35, 8x40, 10x50) is touted to have a generous enough eye relief (1 inch claimed) to see the entire wide field of view, even with glasses, hence the name. They are also nitrogen filled and waterproof. The 8x40 sells for about $260 at discount, though I picked up my seemingly brand new pair for a lot less on the eBay auction (maybe it was a demo model, or the seller, Wholesale Hunter, was trying to generate some business). The Fullfield feels good in the hands, being fully covered with a thin layer of rubber, and has some nice features. The right diopter adjustment has click stop indents which are very difficult to accidently move, and you can lock the focus knob by sliding it. The main drawback is the weight, about 2 pounds, the heaviest in the group. The Burris' field of view is nice and wide at 8.2 degrees, and I was able to see it all easily with fairly thick glasses on. Though the eye relief is claimed to be a full inch, it seemed to be closer to about 20mm, perhaps they measure it from the lens surface rather than the top of the ocular bezel. The eyepieces have long, thin folding eyecups which seem kind of flimsy. The view through the Burris 8x40's was surprisingly good, considering their wide field of view. They were sharp very close to the edge, nearly as good as the Celestrons. The optics are said to be fully multicoated. I tested for spurious reflections by viewing with the bright moon nearby. The Burris' unfortunately, had noticeable scattered light from off axis. There was also some color visible with the moon, mostly towards the edge of field. Overall though, I am very impressed the Burris Fullfields, they would be an excellent choice for those who wear glasses and want a rugged, waterproof pair of binoculars. The Swift Audubon 8.5x44 binoculars are highly regarded birding glasses, and the ED model improves upon it by using extra low dispersion glass in the objectives. The ED's are also supposed to be "showerproof", though I don't think this means they are entirely waterproof. They retail for about $440 from discounters (the regular non- ED model can be obtained for about half that). The Swift 8.5x44's have a solid one piece body covered in the usual pebble grained finish, with some rubber armoring on the ends of the objective tubes. They have a nicely balanced feel in the hands, though they are fairly hefty at 29 ounces. The oculars have hard rubber eyecups which are difficult to fold down. The Swifts have a snugly fitting ocular guard attached to the binocular strap which has an accordian-like piece between the eyepieces, one of the best designs I've seen. Their eye relief is rated at 14 mm, and I could not see the entire field of view with glasses on, though a good portion of it was visible. The Swifts have the same actual field of view as the Burris at 8.2 degrees (the apparent FOV is slighty more). They are very sharp on axis, though the sharpness falls off noticeably towards the edge. I would say that their edge correction is better than the average wide field binocular, though not as good as the Burris' (which has a slightly smaller AFOV). The Swifts are fully multi-coated, and unlike the Burris, had very little in the way of spurious reflections from bright off-axis objects. This may be due to the use of slotted prisms. I could detect very little color with the Swift ED's while viewing the moon. My impression of the Swift 8.5x44 ED's is that they are fine performers, with the only major drawback being their short eye relief. If the regular Audubons are nearly as good as the ED's then they are a true bargain. The Celestron 9.5x44 ED's were one of the first binoculars advertised to have ED lenses. Though I don't believe that Celestron sells them anymore, Eagle Optics is supposed to have the same model available, for around $300. The Celestrons have a two piece body, with rubber covering much of the surface, though I wouldn't call it rubber armoring. I do not believe that they are waterproof. Though they are very light and easy to maneuvre at 24 ounces, (there are even weight-saving cutouts in a bridge piece), they don't look like they would stand up to much field abuse. Interestingly, the Celestron's objectives look nearly identical to those on the Swift ED's. They both have very steep curves on the external surface, and the cells look the same. I wouldn't be surprised if the ED objectives were sourced from the same company, though the rest of the binoculars look very different. The Celestrons have very soft, easy to fold eyecups. The eye relief, rated at 15mm, was adequate enough for me to just see the entire field of view, 6.0 degrees, with my glasses on. Though their field of view is not as wide as that of the Swift or the Burris, the overall image and edge sharpness are as about good as I've seen in any binoculars (I haven't seen the Nikon Superior E's yet). The Celestrons appear to be fully multicoated, but there was some scattered light from the off-axis moon. There was a bit more more color visible than with the Swift ED's but this is understandable given the higher power. The Celestron ED's are excellent glasses for those who do not require a rugged, waterproof binocular. - Fan Tao fantao@___et.att.net =============================== ================================ Binocular List #52: 3/25/99. Collimation, Zeiss, German mil codes ================================== Subject: binocular collimation From: dewees >what distance the binoculars being collimated, should be focussed at. >Would any list member be able to give some advise regarding this?I was an U.S. Navy Opticalman from 1975 to 1980. I'm new to this discussion group. I'm sure the binocular is collimated at infinity. I can't actually remember being told this or reading it in OM 3 and 2 but that was a long time ago. I just whipped out my 10/50's which are perfectly collimated at infinity and there is a lot of parallax evident at close (20 feet) range. So when looking at less than infinity you must be cross-eyed. From a vision standpoint this makes sense because if you collimated at a finite distance you would have to go "walleye" when looking at objects further away - that simply doesn't work. There is also the problem of the optical axis of one or both barrels not being aligned with the hinge axis - That alignment of all three axes is a basic requirement of good binocular collimation, and can only exist with infinite based collimation, so I guess that proves it. I would think that OM 3 & 2, which leaves nothing basic to interpretation, has something to say about this Randy Dewees ------------- (addendum) What I should have said is: Absolutely all binoculars are collimated at infinity. What you got was my thought process instead. The requirement of aligning the optical axes to the hinge axis is to maintain collimation over the range of interpupillary adjustment. The basic geometric statement can be made that these axes are parallel and that requires parallel light (from infinity) as a reference. In the collimation procedure the free barrel is aligned to the hinge first, then the fixed barrel is aligned to the free barrel. Randy =========================== Subject: Zeiss lens trademark From: Fred Watson Note on the trademark in Binocular List #50. It puzzles me a bit, because six years ago, in a second-hand camera store in Britain, I saw an early-model (pre-1907 shape) 6x monocular with the lens trademark. Engraved on the lower prism cover was `From ... to ..., 1904' (I didn't note the names). The only possibility seems to be that I transcribed my notes incorrectly, but I'm usually fairly careful. (I wish now that I'd bought it!) Fred ============================= Subject: 8.5 x 44 From: Bill Cook The Audubon 8.5 x 44 is my birding glass. HOWEVER, the Superior E blows it away. You should find one and trying out. Regards, Bill Cook mgr. Precision Instruments & Optics Captain's Nautical Supplies, Seattle ================================= Subject: German military codes Most of you have this information, but here it is in e-form. If the formatting looks strange, try shrinking the font. --Peter CODE LETTERS FOR NAME OF MANUFACTURER FROM WWII GERMAN OPTICAL PRODUCTS Compiled by Peter Abrahams from 'German Military Letter Codes', John Walter, 1996, East Sussex, Small Arms Research Publications; and earlier, less authoritative lists. CODE MANUFACTURER CITY COUNTRY b e h ERNST LEITZ. WETZLAR GERMANY b e k HENSOLDT WERK FUR OPTIK UND MECHANIK HERBORN GERMANY b l c CARL ZEISS, MILITARABTEILUNG JENA JENA GERMANY b m h JIRASEK (not in Walter) PRAGUE CZECH b m j M. HENSOLDT & SOHNE, A.G. WETZLAR GERMANY b m t C. A. STEINHEIL SOHNE, GmbH MUNICH GERMANY b p d C. P. GOERZ, GmbH VIENNA AUSTRIA b v f C. REICHERT VIENNA AUSTRIA b y g JOH. WYKSEN, K.G. KATTOWITZ POLAND b z z I.G.-FARBENINDUSTRIE, CAMERAWERK MUNICH GERMANY c a d KARL KAHLES (telescopic sights) VIENNA AUSTRIA c a g D. SWAROVSKI WATTENS/TIROL AUSTRIA c a u KODAK AKTIENGESELLSCHAFT, DR. NAGEL WERK STUTTGART GERMANY c c x OPTISCHE UND FEINMECHANISCHE WERKE, HUGO MEYER & CO. GOERLITZ GERMANY c l b DR. F. A. WOHLER KASSEL GERMANY c l n ED. SPRENGER BERLIN GERMANY c r h FRANZ SCHMIDT & HAENSCH BERLIN GERMANY c r n HANSEATISCHE WERKSTATTEN FUR FEINMECHANIK UND OPTIK, FRIEDRICHS & Co. HAMBURG GERMANY c r o R. FUESS, formerly J. G. GREINER & GEISSLER BERLIN GERMANY c x n EMIL BUSCH, A.G. RATHENOW GERMANY d d v OCULUS (optometrist equipment, possibly gunsights) BERLIN GERMANY d d x VOIGTLAENDER & SOHN, A.G. BRAUNSCHWEIG GERMANY d k l JOSEF SCHNEIDER KREUZNACH GERMANY d o q DEUTSCHE SPIEGELGLAS A.G. (telescopes, lenses) LEINE GERMANY d o w WAFFENWERKE BRUNN A.G. (1943-OPTICOTECHNA GmbH) PRERAU CZECH. d p g ADOX KAMERAWERK GmbH (cameras) WIESBADEN GERMANY d p v ZEISS IKON A.G. DRESDEN GERMANY d p w ZEISS IKON A.G. GOERZWERK BERLIN GERMANY d p x ZEISS IKON A.G., CONTESSAWERK STUTTGART GERMANY d y m RUNGE & KAULFUSS RATHENOW GERMANY d y s HEINRICH ZEISS, UNIONZEISS K.G. ('apparently optical' BERLIN GERMANY d z l OPTISCHE ANSTALT OIGEE GmbH BERLIN GERMANY e a f MECHANOPTIK GESELLSCHAFT FUR PRAZISIONSTECHNIK, AUDE & REIPERT BABELSBERG GERMANY e a w R. WINKEL GmbH GOETTINGEN GERMANY e e d KURBI & NIGGELOH (photographic equipment) RADEVORMWALD GERMANY e s o G. RODENSTOCK MUNICH GERMANY e s u STEINHEIL SOHNE GmbH (telescopes & optics) MUNICH GERMANY e u g OPTISCHE PRAZISIONS WERKE GmbH WARSAW POLAND f c o SENDLINGER OPTISCHE GLASWERKE GmbH BERLIN GERMANY f j t PHOTOGRAMMETRIE GmbH (aerial recon. cameras) MUNICH GERMANY f l n FRANZ RAPSCH A.G. (sights, often subcontractor to Busch) RATHENOW GERMANY f v s SPINDLER & HOYER K.G. GOTTINGEN GERMANY f v x BECK & SOHNE KASSEL GERMANY f w r OPTISCHE ANSTALT SAALFELD GmbH SAALFELD GERMANY f x p HANS KOLLMORGEN GmbH BERLIN GERMANY g a g F. MOLLENKOPF STUTTGART GERMANY g k p RUF & Co., formerly CARL SCHUTZ KASSEL GERMANY g u g UNGARNISCHE OPTISCHE WERKE A.G. BUDAPEST HUNGARY g u j WERNER D. KUEHN BERLIN GERMANY g w v ERNST PLANK NURNBERG GERMANY g x l FRANKE & HEIDECKE (photographic equipment) BRAUNSCHWEIG GERMANY g x p HOMRICH & SOHN (photographic equipment) h d v OPTISCHE WERK OSTERODE GmbH OSTERODE GERMANY h f o VALENTIN LINHOF OHG (photographic equipment) MUNICH GERMANY h k m CARL BRAUN KG NURNBERG GERMANY h n a KORELLE WERKE, G.H. BRANDTMANN & Co. (photographic) DRESDEN GERMANY h r w HOH & HAHNE (photographic reproduction equipment) LEIPZIG GERMANY h w t IHAGEE KAMERAWERK, STEENBERGEN & Co. (cameras) DRESDEN GERMANY h x h A. KRUSS HAMBURG GERMANY j f n TETENAL PHOTOWERK, Dr. TRIEPEL, K.G. (photographic equipment) BERLIN GERMANY j f p DR. CARL LEISS BERLIN GERMANY j n h F. TUTEMANN (lens holders & optical equipment) LUDENSCHEID GERMANY j o n VOIGTLANDER-GEVAERT (cameras) BERLIN GERMANY j u x NEDINSCO, NEDERLANDSCHE INSTRUMENTEN, (vehicle & aircraft instruments?) VENLO NETHERLANDS j v e ERNST LUDWIG WEIXDORF GERMANY j x n HELMUT KORTH BERLIN GERMANY k h c OTTO HIMMLER (microscopes, optical equipment) BERLIN GERMANY k l n ERNST & WILHELM BERTRAM (photographic equipment) MUNICH GERMANY k n a DER ROBOT, BERNING & Co., K.G. (photographic equipment) DUSSELDORF GERMANY k q c JOS. SCHNEIDER & Co., K.G. GOETTINGEN GERMANY k r q EMIL BUSCH A.G. (assembled from foreign components) RATHENOW GERMANY k w c GAMMA FEINMECHANISCHE & OPTISCHE WERKE BUDAPEST HUNGARY k x v A. JACKENROLL GmbH BERLIN GERMANY l a e HEINRICH ZEISS, UNION ZEISS K.G. GOSTINGEN l f n REFLEKTA-KAMERAFABRIK, C. RICHTER (cameras) THARANDT GERMANY l m q CARL ZEISS (assembled from foreign components) JENA GERMANY l w g OPTISCHE WERKE OSTERODE GmbH (assembled from foreign components) OSTERODE GERMANY l w w HUET ET CIE PARIS FRANCE l w x OPTIQUE ET PRECISION DE LEVALLOIS, PARIS LEVALLOIS-PERRET FRANCE l w y SOCIETE OPTIQUE ET MECANIQUE DE HAUTE PRECISION PARIS FRANCE m b v I.G. FARBENINDUSTRIE, A.G.; AGFA (cameras) BERLIN GERMANY m c a FOTOWERK, Dr. C. SCHLEUSSNER, GmbH (photographic equipment) FRANKFURT GERMANY m t q PHOTOCHEMISCHE FABRIK ROLAND RISSE GmbH (photographic equipment) FLORSHEIM GERMANY m t r VOIGTLANDER & SOHN, A.G. (cameras) BERLIN GERMANY m t u A. LORENZ (MTU also used for AEG electrical equipment) GUTENFELD m t v A. LORENZ DRESDEN GERMANY n m s RICHARD HOLZ BERLIN GERMANY n x t S.A.I. OTTICO MECCANICA E RILEVAMENTI AEROFOTOGRAMMETRICI (stereoscopic aerial photography equipment) ROME ITALY o c p AKTOPHOT GmbH (photographic equipment) PRAG-SABECHTLITZ o c v W. KLAZAR (precision engineering; reportedly photographic equipment) PRAG o k c HAUFF A.G. (photographic equipment) STUTTGART GERMANY p v f C. REICHERT VIENNA AUSTRIA r l n CARL ZEISS JENA GERMANY A.G. = AKTIENGESELLSCHAFT; JOINT STOCK COMPANY GmbH = GESELLSCHAFT MIT BESCHRANKTER HAFTUNG; LIMITED COMPANY I.G. = INTERRESENGEMEINSCHAFT; UNION OF INTERESTS K.G. = KOMMANDITGESELLSCHAFT; LIMITED PARTNERSHIP OHG = OFFENE HANDELSGESELLSCHAFT; PRIVATE FIRM (literally, 'open trading company') umlauts are omitted ================================ =============================== Binocular List #53: 3/30/99. Collimation, Vixen 20 x 125, repair tool ================================ Subject: Collimation From: Atmj1@___m Today, binos are probably collimated for infinity. However, in times past, many were collimated for some distance less than infinity. I believe I came across that in some reference material presented to me by Daniel Vukobratovich of the Optical Sciences Center at the University of Arizona. If I ever find the primary source, I will post it to this list. Bill Cook, OMC Retired ============================ Subject: A Visual Test And Comparison Of The Vixen 20 X 125 Binocular Telescope From: "Robert B, Ariail" I ran a few tests on the relatively new Vixen 20 X 125 Giant Binocular for my own interest and thought it may be of interest to others who may be curious as to its performance and capabilities. I also compared it with a Nikko 20 X 120 WWII binocular (S#779) that had been put into good shape a number of years ago. Appearance & Details: Very appealing to the eye. Well made and finished in white. Has a convenient handle for carrying the 24 pound instrument easily. The handle also functions as a line of sight finder for bright objects or specific positions in the sky. An optional standard finder is available if desired. The mounting while on the light side and appearing rather flimsy, performs well with the Teflon coated trunions held in position with lock ring supports. Tightening the lock ring supports provides the desired friction. The mounting is reasonably stable if fully opened, locked into place and tightened properly to avoid vibrations, etc. The portability of the mounting more than makes up for any deficiencies of being on the light side. Vixen claims the optics to be multi-coated and fully baffled. Field of View: Vixen gives 3.0* as did Nikko. The exact field of view that I found as determined from measured star patterns is: Vixen = 2.9*; Nikko = 3.2*. The image fall off at the edge of field with both glasses appeared about the same. It may have been slightly less in the Nikko considering the more than 11% greater field of view. This deterioration became serious at about 25% from the edge of the field of view in both binoculars. Magnification: Specifications provided by Vixen indicated an f/5 system of 625mm f/l. Although marked at 20X on both binoculars, I attempted to confirm the exact magnification by carefully measuring the exit pupil in bright light (with a precise caliper) and dividing it into the aperture of the objective lenses. The results were: Vixen = 20.67; Nikko = 19.44. An exact focal length via the knife edge test would have been a useful aid in this procedure, but disassembly would have voided any warranty on the Vixen and was therefore not attempted with either glass. All things considered, the manufacturer's stated powers were quite good. Color & Ghosting Check: The Vixen binocular was tested on various street lights - Hg & Na - to make a determination of the color correction and the degree of ghosting. The 'multi-coated' optics were apparently quite effective against ghosting since evidence of such was minimal. Glare was clearly seen as the test street light angled out of the field. This, however, seems to be the case with any binocular or telescope. An examination of the large exit pupils with a magnifier (a la Dick Buchroeder) revealed no evident 'prism leak' that I could detect. With Hg, there was color galore as expected. Nevertheless, it appeared to be slightly less (subjective) as compared with an average of many other optics - binocular or telescope - over 4-inches aperture with fast to medium systems. Eye Relief: Vixen gives 20mm of eye relief for the binocular. The Nikko is somewhat less at about 15-18mm of eye relief. Without glasses, both binoculars were quite neat and provided full image circles (field of view) at a convertible position on the binocular. With glasses ( I have some astigmatism), the full image circle was just available with the Vixen but sizably reduced in the Nikko. Magnitude Depth: The limiting magnitude test was more of a relative comparison of the two binoculars due to my location in Columbia, S.C. being within the city limits with the resultant light pollution. It should also be noted, however, that on the evening the binoculars were tested it was dark, steady, and clear with few lights in the area. This estimate was made with an AAVSO (American Association Of Variable Star Observers) "B" chart for the field of R Leporis. This chart provided a limiting magnitude of 10.6. Careful visual estimates with the comparison stars gave a limiting magnitude of 10.4 for the Vixen and 9.8 with the Nikko. There is little doubt in my mind that the Vixen under dark, steady conditions and with the observer's vision dark adapted, would easily reveal stars of 11.5 magnitude near the zenith. (The R Leporis chart provided a field at an elevation of not more that 40* in Columbia during February) Features: The medium field oculars along with the freely rolling prism housings allowing adjustable interpupillary width, give a comfortable view and work very smoothly. Eye relief is good as stated above. The first thing that is quickly noticed in the binocular is the velvety dark field the glass provides. This illustrates probably the best feature of this glass as compared with older giant binoculars and smaller modern ones - its outstanding light grasp. The mobility of this binocular and tripod make it "feel" much lighter and smaller than it actually is. Set up properly it handles well and is a pleasure to use and move about. It can be set up and in operation in two minutes; a feat which is rarely possible with the usual giant binocular and its mounting which in many cases may weigh 100 or more pounds. In summary, the binocular performs moderately well optically and very good mechanically. It is advertised as a "binocular telescope," but such is not the case. This instrument is a pure binocular with none of the primary characteristics of any binocular telescope. Is it worth the retail price of $3200? Well, that all dependents on the individual observer. For a binocular specialist used to the characteristics of the instrument and resigned to image degradation at the edge of field, possibly so. For those desiring refractor like images and used to a narrow field of view with pin point images at the edge of the field; probably not. There is no question that a great deal of fun may be had with this instrument at a dark sky site sweeping up star fields with clusters and nebulae. A very comfortable, quick and pleasant way to survey the skies. Bob Ariail =============================== Subject: Repair tool. From: Peter Abrahams, telscope@___.com I found an expensive tool for unscrewing thin wall tubing that is threaded into other parts. Strap wrenches are OK but this looks much better, at least the catalog makes it look better. It resembles a spanner, but the jaws are a coiled spring made of a strip of sheet steel. You coil the spring around the tube & then torque on the spring. http://www.rolyn.com/rolmis3.htm (no picture here, there's an image in the printed catalog) ROLYN SNAKE PLIER MODEL SZ4/C-55 The SNAKE PLIER consists of two coil springs with their turns interleaved, attached to two arms projecting from and sliding for adjustment of diameter on the main supporting bar. Coil springs, each one adjustable for a range of diameters, can be quickly interchanged giving an infinite variety within the capacity of the tool. A spring of approximately the same diameter is placed over the work to be turned, and the coils of the spring tighten as the main bar is turned, thus effecting a tenacious, equally distributed friction grip which renders the assembly or dismantling of the most fragile threaded cell or thin wall tube the simplest operation, without risk of damage or marking. STOCK # Description PRICE 90.0275 Snake Plier with 70mmØ coils 232.92 90.0280 Spare coils for 70mmØ 126.36 90.0285 Small coils for up to 35mmØ 204.29 90.0290 Snake Plier with 150mmØ coils 321.49 90.0295 Spare coils for 150mmØ 120.89 ========================= ========================= Binocular List #54: Photography, Help Wanted, Bnox ======================================= Subject:Photographing binoculars From: Peter Abrahams, telscope@___.com I'm going to get up on my soapbox again. Previous harangues have concerned the need for all of us to accumulate paper (catalogs, manuals, brochures, etc.). Now the issue is the importance to all of us -- repairmen, collectors, dealers -- of photographing the binoculars that pass through our hands. These photos will serve many functions: they will let you ask others about specimens; they will be useful for insurance; photos are very helpful when time comes to sell a glass; but mostly they will be an important historical document. I don't know who among us will gather the ambition needed to write that book length text we all need: the English language history of binoculars. But I am sure that illustrating such a book is almost as much work as writing it. If we start accumulating photographs of binoculars, that would be a great service to an author, and will greatly speed the day when we all have such a book. This documentation does have a few requirements. 1. Tripod mount the camera, use cable release. 2. Illumination: use either a tent; or use several lamps or flashes, preferably pointed backwards into some reflective mylar. 3. The image, either the entire glass or a detail, needs to almost fill the negative; and so two, high quality lenses will be needed. 4. Depth of field: details at the front and rear of the glass need to be in focus. 5. It does take a good amount of time to do this. It would be very discouraging to take all these pictures & then be informed by an author that they aren't good enough for reproduction in a book. But there is no black magic here: if they're sharp, details well illuminated, preferably no shadows, they should work well. Just look in books by Seeger or Rohan for examples. --Peter ====================== Subject: Help Wanted From: Atmj1@___m (Bill Cook) Captain's Nautical Supplies - America's most respected name in optical instrument repair -- is looking for a dedicated Optical Technologist / Optician to work in our Seattle, Washington facility. Duties will include (to some extent) several aspects of the optical industry: * Military and civilian instrument repair (primarily civilian binoculars and telescopes) * Limited optical element fabrication (production of lenses and telescope mirrors) * Limited Prototype work on new telescopes * Occasional involvement with the sales of binoculars and telescopes (Captain's has the largest selection of binoculars and telescopes on the West Coast.) * Occasional involvement in the production of Amateur Telescope Making Journal. Training as a Navy Opticalman 2nd Class or better preferred, but not required if equivalent civilian experience can be shown. College degree preferred but not required. Good grooming standards and interpersonal skills a must. We are looking for an individual to whom working with optical instruments is as much a hobby as it is a profession. Earnings will depend on experience. Captain's has medical and dental benefits and 3- week vacations after 2 years of employment. Qualified applicants may send resumes or memos expressing interest to Bill Cook at: or William J. Cook 17606 28th Ave. S.E. Bothell, WA 98012 ============================== Subject: Bnox From: Fan Tao Here is an entertaining web site from the makers of the ultra-inexpensive Bnox binoculars that use mirrors and plastic lenses: http://www.bnox.com/ Take a look at their "Evolution of Binoculars" timeline. The optics of the Bnox were apparently designed by a Dr. Stephen Fantone of the Optikos design house (Cambridge, MA). Fan Tao fantao@___et.att.net ====== I have heard these Bnox are of very poor optical quality. They use mirrors instead of prisms & have molded acrylic lenses; their flimsy construction doesn't hold collimation, and they are fixed focus. They are interesting because the layout places both objectives to the right of both eyepieces. The outer (rightmost in use) objective has two inversion mirrors (light bounces vertically), then two reversion mirrors (horizontally bouncing). The inner (left most) objective sends light to reversion, then inversion mirrors --Peter. http://www.patents.ibm.com/details?pn=US05633753__&language=en =============================================== ======================================== Binocular List #55: 4/23/99. Photography, books, image quality ======================================== Subject: Photography From: "Martin, Dick" I have some photos now. A few went to Rohan for his next book. In addition to the technical format, I suggest a requirement to display certain features as a baseline then additional shots to cover unique features. I have done this type of photography and could lend a hand but I am not knowledgeable about binocular technical or historica other than what I have picked up as a hobbiest in the last five years. Who will actually retain the photo archives from this collection process? A tip for photographers. Remove the yellow contrast filter so useful in landscapes. The black and white images in a binocular make shadow detail difficult enough without adding more contrast. Dick Martin -------------------- > display certain features as a baseline then additional shots to cover unique features. Yes, a standardization would be useful. Of course, if it's like pulling teeth to get good sharp pictures anyway, additional requirements would eliminate some volunteers. My doubts are more like, you'll get help, but the photos will be washed out, fuzzy, etc., & then you'll have to tell them they're unusable. > Who will actually retain the photo archives from this collection process? That would be up to the photographer, though a publisher might have something to say about rights. As far as a permanent archive, hopefully a book will be filled with illustrations & serve that purpose. I have made a point of collecting photos, but they've been from people asking about value; and some from repairmen. My collection of photos is one of my most useful references. >The black and white images in a binocular make shadow detail difficult >enough without adding more contrast. Re: contrast. Jack Kelly got a parachute cloth tent & multiple spotlights. It eliminated shadows, which is very helpful, but might have actually gone a little too far in reducing contrast. A professional suggested that a slightly better technique might be spotlights or flashes pointed backwards into mylar. It is a tough problem, proper exposure of hard black binoculars, especially since white background seems best. I shot part of Fred Schwartzman's collection, using two desk lamps & a white sheet backdrop. They were sharp, but only barely good enough to use; contrast was mediocre. It is discouraging to travel to a collection & have to spend time on photography, rather than on inspecting binoculars. Steve Rohan's photographs are good, Jack Kelly likewise, Kevin Kuhne has taken many examples of good binocular photography, and Seeger's books are a model. The problems are not that severe, it just takes time & that is one thing you don't have when visiting a collection. One binocular is black and glossy, the next is flat black, another brown, then mother of pearl; and you often have to re-shoot to get a good image. So, photography by owners would be immensly helpful. -- Peter =================================== Subject: The book on binoculars From: Atmj1@___m > I don't know who among us will gather the ambition needed to write that > book length text we all need: the English language history of binoculars. If Barlow comes to take over all the workaday work aspects of nuances of running the Journal, I will have the ambition. That is unless Peter beats me to it. In fact I will eventually do a book even if Peter does beat me to it. I have been talking to Perry R. about the matter for years. However, other pressures dictate that the time is close but not here. My youngest son will be leaving the nest in 2 years and after I get finished with replacing all the broken branches, I will start the book. I think a book by someone who actually goes inside these things on a daily bases would be worth a look. Besides, I have never even come close to justifying that History degree. Still, while in an effort to turn a profit, I can't photograph every piece that comes across the bench, I have tried to photograph some of the more interesting pieces. I would recommend that Peter (if he has the time and desire and it can be economically), keep a collection for all concerning to donate to and copy from. I would assume that anyone wishing to download images would be willing to give credit where do. Bill Cook, Mgr., Precision Instruments & Optics, Captain's, Seattle; editor / publisher, ATM Journal ---------------- Bill & I share the ambition, and there is plenty of subject matter for more than one volume. Steve Rohan continues to work on publications, and so there's hope (if there's immortality). An image archive, with all 'rights' retained by the photographer, would be useful to everyone. An electronic file, like the images available at my 'ftp site', is important, but these downloadable images won't have the quality needed for a book. An electronic photo has to be of a huge file size before it is reproduces nicely. However, I certainly extend an offer to post further images, like this: http://www.europa.com/~telscope/binoc1.jpg found at http://www.europa.com/~telscope/ --Peter =================================================== Subject: Optical quality From: Peter Abrahams A couple of our members have noted that an interesting subject of discussion would be: What are the qualities that make a binocular really excellent? I agree, and since I'm most interested in what makes a glass give a really excellent image, I'll start off with that subject. There's a lot of other qualities that make a great binocular, but the image is a good place to start. --Sharp image mid field is certainly #1. However, this problem has been solved for telescopes for some centuries now, and certainly the first Zeiss binoculars of 100 years ago are quite sharp mid field. My personal feeling is that most decent quality consumer binoculars of today are sufficiently sharp mid field. However, there are people whose eyes are much more acute than mine & they say that certain models are quite a bit sharper than others, as shown in simple tests like viewing a printed page at a distance. These eagle eyed types are not just less myopic than I, even corrected vision can vary; the eye has spherical aberration in varying quantities. This is why I tried to set up an auxiliary scope behind a binocular, as related in the list of a few months ago. --My criteria for a good binocular involves how sharp the image is at the edge, which is mostly a function of astigmatism of the eyepiece. If you focus on a target mid field, then move the binocular so the target is at the edge, it will be out of focus in every binocular I've used that has a decent field of view (it is easy to just insert a field stop in the eyepiece so that the whole narrow field is sharp). Junk binoculars get blurry just off the center, and excellent models are in focus across almost the whole field. Some experienced users don't care about this quality: they figure that they just move the glass to view the object mid field; and unaided vision is only sharp mid field - so this is an unnatural view and uncomfortable to some. --Low distortion --Color correction & color fidelity, critical to birders. --Pupil correction: the most common violation is 'kidney bean', when a curved portion of the image blacks out when you slightly move the glass; this is due to spherical aberration of the exit pupil. There are other aspects of pupil correction that I'm a little fuzzy on. If the binocular has an exit pupil exactly the same size as your eye's pupil, any slight movement of the glass or rotation of the eye will cause partial blackout; which is a similar effect but is vignetting & not related to correction (if I'm correct). --Freedom from ghost images & stray light. --The placement of the image in physical space: Eye relief is critical to people who need to view while wearing their spectacles. Unfortunately, adequate eye relief for those folks (about 20mm) means that other viewers have to hold the binocular away from their eyes by that distance. There are compromises: you can have retractable eye cups. But, to my limited knowledge, an eyepiece is optimized for a particular eye relief. If you try to simultaneously accomodate spectacle wearers & others, you have to compromise the correction of aberrations. (Either that, or I'm wrong.) Other aspects of a good binocular include: --Water resistance: if you live in a dry environment, you might underestimate this one. Not just rain & dunking, but moisture resistance. --Ruggedness: Swarovski has a very rugged binocular, but I believe it is at the expense of serviceability, as they are more or less filled with foam. --Ease of handling: Most people think that Porro I binoculars are easier to handle than 'twin cigar' roof prisms. It is my experience that this is true for two reasons: first, the Porro I has a wider body, so your hands are more by your temples than your nose. Second, the really long narrow roof prisms, like the Hensoldt, do not have the compressed optical path that the Porro I has, and the objective sits out in front of you by 9 inches or so. This means that any small movement of the glass moves the objective twice as far as a 'shorter' binocular, and leads to more image 'jiggle'. Final note: this isn't a totally academic exercise. There are people out there, designing & marketing consumer binoculars; and they have been known to ask the advice of some members of this list. I highly doubt that I'm entirely correct in all the above details, and hope for corrections & further input. I wrote an article on related issues for the local amateur astronomers. It can be found at http://www.europa.com/~telscope/binotest.txt =================================================== ==================================================== Binocular List #56: 4/25/99. New binocular, binocular design, photography. ===================================== Subject: New binocular From: DeutOptik@___m As it happens, we are among "those people" currently designing an all-new binocular. We've teamed up with a Swiss subsidiary of Leica to develop a new top- of-the-line glass starting with the 6x42 Sard as a model (seemingly the favorite glass of almost all collectors). Yup, it will be relatively heavy (and not cheap), but we hope to combine a 5 element (minimum) Erfle eypece with modern lens design and coatings to produce a 11+ degree field of view with crystal clarity virtually to the edges and color correction up there with the best of 'em. All the other items you mention are part and parcel of our plans as well; it just remains to be seen how many of them we can incorporate into the design and still keep the cost underneath that of a luxery automobile. Our hope is to have something by the end of the year; we'll keep you informed. s/ Mike Rivkin ======================= Subject: binocular design From: Randy Dewees On what makes a great binocular. I must say that really high quality binoculars have a certain aroma, especially German binoculars. I have a learned pleasure reflex to that smell which heightens my enjoyment. The exit pupil correction is important! The exit pupil is simply the image of the entrance aperture formed by the intervening optics. The rolling kidney bean effect is the result of spherical aberration. There can be other aberrations of the exit pupil such as coma, astigmatism, and distortion. I believe these can degrade the ease of "linking up" the binocular to the eyes. In my experience all great binoculars are easy to look through. By the way, the exit pupil occuplies a fixed location for any particular focus setting - there is no practical way to vary the eyepoint. Another image feature of great binoculars is good control of lateral color. I find colour fringes on off-axis objects to be distracting even when looking at objects in the center of the field. Finally, contrast is important second only to sharpness. Some binoculars have relatively low contrast without having obvious design deficiencies. There just isn't the sparkle that great binoculars have - that better than real life quality. I think this results from all the contributions of little things like less than perfect lenses surfaces, coatings, glass, and maybe a somewhat compromised design. Randy ============================ Subject: binocular design From: "Loren A. Busch" RE: Checking For Sharpness at Edge of Field A more effective way to check for sharpness of image across the entire field is to focus on an object at the EDGE of the field first, then move the subject to the center. This tends to show problems (or good performance) better than focusing in the center of field first. My guess is that eyes, especially in older/less accommodating eyes, seem to adjust better if focused first for the usually good on axis portion of the image, but not the other way. This tip from Bill Cook. Your point about constantly hitting the edge of the field when the exit pupil matches the pupil of the eye is a point that is given much to little attention. In fact, a lot of attention is given in advice to beginning amateur astronomers about 'matching the exit pupil to the eye' to avoid 'wasting light'. I sometimes wonder if these writers have ever spent any amount of time actually using binoculars for astronomy because they seem to ignore (or are ignorant of) two important aspects of binocular astronomy. First, if the exit pupil matches or is smaller than the pupil of the eye, you are constantly fighting to keep your eyes centered, and IPD adjustment becomes very critical. Two, it becomes much harder to even find the exit pupil and keep aligned with your eyes. During daylight use, we have a very bright field in the exit pupil that makes it easy to align with our eyes and make adjustments to eye relief and IPD. At night, looking at the sky, we don't have that bright, well defined edge to the field, and getting the eyes aligned exactly with the exit pupil is much more difficult. I point out to people that not only is it important to place binoculars on something solid like a tripod, but for astronomy, if you can also rest your head on something to essentially lock your eyes in place behind the binocular. The eye relief problem is being addressed more and more by binocular manufactures. Virtually all bino's marketed today have roll down rubber eyecups, an increasing number of medium and even low cost bino's have pop-up push-down eyecups. This feature used to be found mostly on high end products. The Zeiss "B" (long eye relief) series used to be an option, a separate part number. Now most models that had the "B" ordering option are "B" only in the catalog. Presenting and selling binoculars to the general public on a daily basis gives a chance to see some of the "people" aspects of binoculars. Here are some general observations. 1) Tremendous range of what people expect a "good" pair of binoculars to cost. About 20% are amazed that they may need to spend more than $100 get get a binocular of reasonable quality. 2) A near obsession with "Waterproof" binoculars. Many, many buyers are convinced that they need a waterproof binocular, regardless of how they are going to use them. 3) Wide apparent field of view impresses people much more than image quality. A designer can get away with distortion and fuzzy images at the edge if the eyepiece design gives a wide apparent field. 4) A small percentage of the general public have realized that investing in a top end binocular will provide a lifetime of good seeing, and either save for or make the sacrifice to buy a Lecia, Zeiss, Swarovski, or high end Nikon. Most of the buyers of top of the line binoculars are buying for their ego and pride of ownership: the quality they are getting is just a side benefit. 5) The fit and feel of binoculars in the hands of the user can be quite subjective. Part of this is physical, such as how deep an individuals eyes are set in their head. I frequently see people choose not the optically best from two or three binoculars that may be in the same price range. They choose the binoculars the "feel best". Gee, I do ramble on. Busch ============================== Subject: Photography From: "Martin, Dick" Regarding exposure. Binoculars on a white background are the same exposure nemesis as the black cat in the snow. The way I compensate for this is by setting exposures with my old 18% gray card available from any good photo store. It always work dead on. Place the card in front of the binocular so that the card is perpendicular to the light source. Get the camera off the auto exposure mode. Do not let your body interfere with the light source(s). Allow the card to fill the viewfinder. Manually set the exposure. Remove the card. Change nothing . The exposure meter will change reading when the card is removed but that's because the meter is averaging a whole new set of brightness values. Disregard that and shoot. Dick ================================= =================================== Binocular List #57: 5/5/99. Design, photography, Nikon Venturers, collimator ================================== From: rab Subject: binocular design It seems to me that the most enviable WW2 hand-held binoculars were without doubt the German 8x60 wide angle, 'gas-mask' designs. Other sought-after models, like the SARD 6x42 and Nikko 10x70, featured wide angles and comparatively large eyerelief. Image quality at a given APPARENT FIELD OF VIEW angle is surprisingly the same in all the good old binoculars, and is not a distinguishing characteristic. My list of the most important features in a binocular are, in order of importance: 1. Eyerelief 2. Apparent FOV 3. Exit pupil diameter (large being better) 4. Image quality and freedom from ghost images Regards, Dick Buchroeder ============================================ Subject: photography From: Atmj1@___m Peter et. al.: I am aware that electronic photos would not be good enough for publication -- especially since too many people don't know what TIFF is all about. However, if the images were saved as TIFF files (scanned at 200 dpi or better), they could be passed along on Zip Drive or CD and life would be good. The every-popular JPEG files are harder to work with and they lose data each time they are transferred. Regards, Bill Cook Manager, Precision Instruments & Optics, Captain's Nautical Supplies, Seattle ==================== Subject: New Nikon Venturer 10 x 42 From: rab I've gone back to Jensen's Ammo store twice now to look more carefully at their Nikon binocular that we assumed to be the Venturer LX. However, there is no "Venturer LX" imprinted on the binocular or on its box and enclosed documentation. Jensen's binocular looks like the Venturer shown on the Nikon home page, but Jensen's price of $1143 seems lower than Jensen would charge for such things. I took them outdoors today and examined solar reflections off chromed bumpers. Image well-behaved, hint of some ghosts. Also did out-of-field look in vicinity of sun, and while there are ghosts they are pretty darn good for such tests. Wearing my glasses, I can see the field stops indoors; when I go outdoors, my pupils have contracted to the point that I can no longer see the field stops. I examined images very carefully as they travel from center to edge of field. The images are NOT PERFECT! But about as good as anything I've seen in binoculars before. Next step would be to star test them at night. Distortion is very low; verticals stay almost vertical, horizontals almost horizontal. Compared them to Pentax 10x40(42?) Waterproof, Zeiss 10x40(42?), and Leica 10x40(42?) and the Nikons are, in my opinion, very preferable, most particularly because of the enhanced eyerelief, but also because Zeiss and Leica have conspicuous distortion. I'm schizophrenic about distortion these days; can't make up my mind anymore whether it ought to be required, or praised when it is corrected. The Pentax has a noticeably lower contrast image than the others, but its comparatively long eyerelief makes it good value. I bought the 8x42,which has enough eyerelief. But its reduced contrast by comparison with the more expensive binoculars is its weak point. I examined the exit pupil of the Nikon 10x42 with a good magnifier, and it is magnificently baffled, with no hint of a leak or incipient leak. Best in the business! Examined the Nikon from the objective end, allowing sunlight to enter and illuminate the input baffles. Has scads of baffles, never seen anything so complicated in a commercial binocular before. Bravo! Like all similar binoculars, it does show its secondary color; it would be nice to see them use exotic glass to fix that, and no doubt the next generation would do so. It's comparatively easy to do just by throwing a little extra money at the problem. Regretably there is almost no commercial demand for an exotic 10x70 binocular these days, so I don't think we'll see Nikon make anything larger than the 10x42 Venturer (or whatever other name it may go by). If I were a hunter or birder, I'd sure snap up a pair of these Nikons just in case they decide to discontinue the line! In my opinion, it's vastly superior to any other similar binocular now on the market. Regards, Dick. ======== From: Steve Stayton Glad you agree with me on the Nikon 10X42. The 8X42 is equally impressive with an extra 1mm of eye relief (20mm spec vs. 19mm). May get a chance to see both at the Guild Camera Shop in Phoenix next weekend, they have best stock in AZ of binocs. I can assure you that the one at Jensons is the Venturer LX model. Also called the 10X42HG DCF WP for High Grade, Dach, Center Focus, Waterproof in Japanese Deutsch speak. Nikon USA seems to not have a clue as to how to market this stuff. These glasses have been out for almost 2 years and few people know it or appreciate it. I first saw one of these last year in Boston and knew right away it was the best all around binoc today (since I had the Leica and Zeiss Night Owls to compare to right there). Mail order prices range in 1050 to 1150 that I have seen from reputable dealers over the last year or so, worth every penny (even though the images are not 'perfect' over the full field), but call to check latest prices. I got my Leica 7X42 just before the Nikon models were available or I would have the Nikon. Have Matt Boston's geiger counter and have not found anything very hot yet except the expected EKC 7 inch f/2.5 Aero Ektar WWII lens. Will have to get together this week and check your stuff (and our Russkie 80's) for glow in the dark. Regards, Steve ======= I inspected both models of these Venturers at Hunts in Boston, and while I didn't have a comparison glass, I was very impressed, especially with the image sharpness to near edge. They are comfortable to use, with a good shape and textured housing (not rubber, which deteriorates too fast for me). My only objection is that they are very heavy. --Peter ================================================= Subject: collimator v. collimator From: Cory Suddarth I've got a quandary to post to the group. I have two collimators at my disposal,and while they display similar error levels on binoculars, the claimed error value is very much disputed. Here's the problem. The U.S. Navy collimator is expressed in ten (10) minute(s) of arc increments, six (6) units equal one (1) degree. This scale then reads six (6) degrees in four (4) quadrants, up, down, side-to-side, the zero point originates in the center. The Fujinon collimator [Universal Binocular Measuring Machine] uses a projected scale that goes through the bino and is displayed on a ground glass screen. Claimed error for these increments are one (1) minute of arc each. Here's where the fun begins. If I purposely tweak one (1) degree of vertical error (or step) in a pair of 7x50 Swift Seahawks using the Navy Mk V, then place it on the Fujinon collimator, the error should be off the screen of the Fujinon. Vertical error only goes to twenty (20) minutes ,therefore, sixty (60) minutes of arc, or one (1) degree error would not be on this scale, off the chart! Well, this is not the case. One (1) degree of step comes to the tenth place on the Fujinon scale. Question is, if these are indeed one (1) minute of arc, Why does an error of sixty (60) minutes show up as only ten (10) minutes of arc? Off by a factor of six (6)!! Here, let's try again. This time I will induce an error of only thirty (30) minutes of arc on the Mk V, 1/2 degree error. Now put this on the Fujinon collimator. Theoretically, this error is over the scale limits (by 10 minutes of arc) but should still show up on the screen. Here's where the target falls, it falls on the fifth place, five minutes of arc. how can this be??, again off by a magnitude of six (6). My analyses is that the scale on the Fujinon collimator is not expressed in minutes of arc, but tenths of a degree. This would explain the one degree error landing on the tenth place, and the 30 minutes of arc error showing up on the fifth place. Check points. Both machines have been checked for calibration, and so to verify, a binocular of a known angular value is placed on the Mk V. Within minutes of arc, the FOV matches what is expressed. So now let's put this on the Fujinon. Fujinon has a power scale. Now the bino's line up to within a few tenths of the power expressed on the glass. Both machines read true. If either machine is off, it's certainly not by a factor of six!! Does anyone have any experience expressly with these two machines?? I use these both daily, and as long as I think tenths of a degree error on the Fuji, not minutes of arc, we get along fine. Help me O-B-One. Cory Suddarth, Senior Optical Technician, Orion Telescopes & Binoculars corys@___el.com http://www.telescope.com (831) 763-7006, x271 ================================= ================================= Binocular List #58: Nikon 10x42; Testing Collimators; Saegmuller; Rangefinder ========================== Subject: Nikon 10x42D From: rab I need to add an addendum to your Binocular Newsletter to share some bad info on the Nikon 10x42D ('Venturer?...still no name on the box to that effect). Steve and I visited Guild Camera Store in Phoenix, AZ. They have a web site and an 800-number, and were fully cooperative with us as we looked over all the interesting high-end binos, including the two Nikons we came to see: 8x42D and 10x42D. As before at Jensen's Ammo, we tested them in various ways, including examination of the exit pupil with a loupe. Two pair of 10x42D's were available. The one on the counter showed a small cosmetic flaw on one of the internal surfaces, visible with the loupe. Probably harmless, but I asked to see the second set they had still in the box. Examined it with loupe, no flaws, examined it indoors, then examined it in full-sun outdoors. It appeared magnificent in all respects. Bought it on credit card and took it home to Tucson. Night-time testing showed that the phase correction of the left side was flawed: significantly bright diffraction spikes were observable on very bright objects like oncoming headlights and stadium lights in the distance. The right side was free from the problem. Shining flashlight into the objective end showed colored reflections that were very different on left vs right side, indicating either poor quality control, or at the least, that the optics were not from the same coating run. In my opinion, there was also narrow-angle scattering around bright lights. I was surprised to find that even in darkness, I was unable to comfortably view the field stops even though this model features 19mm of eyerelief. I should report that I'm slightly farsighted with about 2.5 diopters of astigmatism, with the zero power axis aligned nearly horizontally. Thus, in the vertical direction, I may have as much as 3.5 diopters of positive power in my spectacles, which shifts the eyepoint nearer the eyepiece than if I weren't wearing my spectacles. Thus, a farsighted person (hyperope) requires more eyerelief in his binoculars than does a nearsighted person(myope). However, the Nikon 10x42D does better for me than comparable binoculars from Zeiss, Leica, Swarovski and Pentax. Since amateur astronomy is a big part of my optical life, I decided to return the binoculars for refund. Regards, Dick Buchroeder. ============================== Subject: Collimator Testing From: Steve Stayton In response to your request on Binocular List #57 about discrepancies on angle readings between your two binocular collimators I have the following suggestion. It would seem that at least one of the collimators is incorrectly calibrated for angle measurements. But first the distinction must be made between collimation angles measured in object space (objective end of the binoc) and in image space (eye end). A target collimator by itself (that just projects a reticle image into the binoc) without a reading telescope as part of the system may have a scale that reads in object space angles only. The collimation angles in image space, as read by looking through the eyepiece of a binocular with a test telescope will be magnified by the binocular magnification. That is, an error of 2 minutes at the collimator will be approximately 14 minutes at the eyepiece of a 7X binocular. So you must know where the collimation angle is measured, object space or image space, this is very important. The US Mil Specs that I have seen specify tolerances on collimation in image space as is most appropriate because that is the error the eyes sense. It is possible that one of your collimator rigs is reading in object space and one in image space so that angle readings would differ by the magnification of the instrument being tested. But it could just be an error in scale marking on the Fuji as you indicated (poor translation from the Japanese?). One way to check the angle readings of your collimators is to place a prism wedge of known angle of deviation on the bench in place of the binocular and see what your collimator reads for the angle displacement of the target reticle. The target reticle image will only be displaced along the direction of the prism wedge and will not be magnified but this gives good angle calibration. If the wedge deviation is 2 minutes and 30 seconds say, then the collimator should read the exact same angle, 2 min. and 30 sec. in image space. The best way to know the exact angle deviation of a prism wedge is to measure it with an autocollimator or theodolite. Let me know if you need help with this part, the procedure is straightforward. Steve Stayton =================================== Subject Saegmuller From: THGART@___m Would you ask your group members to share any information they might have on G. N. Saegmuller (or questions about him, for that matter, I’m becoming knowledgeable about his life). I would also ask you to share with them the fact that I’m looking for a pair of 'Triple Alliance' B & L -- Zeiss -- Saegmuller binoculars, size not specified but in good condition and preferably center focus, for not more than $100. Tom Garver (Tom has accomplished some very productive research on Saegmuller, a man about whom very little has been published. More unusually, it seems his research will actually reach the printed page, so any help will be very useful. --Peter) =================================== Subject: Binoculars with built in rangefinder? From: "R.F.Bolton" Peter I had a request today for information re binoculars that Sport Archers, in the USA are using to determine the distance to the target. Bushnell makes a pair of 4x? that use a laser and are good to 400yds. Bushmaster make a monocular that uses a graticle. Greater detail is not known at this time. Do you know of such a beast and where info may be found?. Rod Bolton. =================================== =========================================== Binocular List #59: Yellow Zeiss prisms, New Bushnell WA, Rangefinder, ============================================ Subject: Yellow color in Zeiss prisms From: Peter Abrahams, telscope@___.com Some of the best binoculars ever made were the Zeiss Porro I glasses from the 1950s. However, many of them are suffering from a yellow cast to the image. I had thought that it might be from an exotic high index glass that discolored in time. Recently, I heard that it was the cement used in the binoculars that was yellowing, whether in the ocular or the prism was unspecified. I would greatly appreciate any information on this. These are fabulous binoculars, but the discoloration can be severe; and if it is the cement, then they are repairable. Thanks, Peter ===================== Bushnell WA 10 x 50 From: rab Have you heard anything about the newest addition to the Bushnell Xtra-wide, a 10x50 with what appears to be a 95-deg AFOV? http://www.bushnell.com/productinfo/binoculars/xtrawide.html Price: $119 from Eagle. --Dick Buchroeder ======================= Subject: Bushnell Laser Rangefinder From: "linda" Hi there, I am a newcomer in the binocs group and this is the first time I try to be useful to members. I own a Bushnell yardage pro 900 which is twice ranging the Bushnell 400. It is not a true binocular because it has one only exit eyepiece. Through the eyepiece the target is aimed and after the launch of the laser beam in the same eyepiece is read the distance of the target. My own which should range up to 900 Yards has low redundance . It is very difficult to range ,in open sun, also at 500- 600 Yards. It ranges at these distance only with a very reflecting target. It works much better in dimmed light. Near the sunset it ranges to 900 yards with medium reflecting targets as walls and vertical obstacles. I found very much effective the Russian Army Laser Rangefinder which is bulky but ranging easily to ten miles in every condition of light. Russian Laser rangefinder has only a great defect: It is very dangerous for people's eyes. I never saw a Bushmaster monocular but I believe it works like militrary binoculars with reticle. This system is far less accurate in ranging than laser rangefinder. I know two only true binoculars with rangefinder the Leica Geovid 7x42 and its military Brother Leica Vector 4000. But they works with infrared rays like modern cameras. As far as I know the Bushmaster type rangefinders are useful playing golf where a great accuracy is not needed while where a great precision is necessary( adjusting optical rangefinders for example) a laser or infrared rangefinder is indispensable. Excuse me for my poor English. Giancarlo Bozzano ----------- (I asked Giancarlo for an introduction, and also asked about the 3 Italian makers I'm aware of: Koristka, San Giorgio, and R. Esercito. --Peter) From: "linda" Hello Peter, I am a collector of military binoculars,optical rangefinders and sights. Formerly I collected Leica M and R Cameras and lenses. After twenty Years of camera collecting I got tired of this nothwistanding my collection had become one of the more complete in Italy. On day at a flea market I found a Leitz Flakglas and I was fascinated by that marvelous object built by my beloved Leitz. This was the beginning and from then I began to look at optic instruments with a captive Eye.After I discovered stereoscopic rangefinders which have been a mistery for me for two years or more because having got firstly stereo rangefinders with fixed marks (mit fester skala in German) I understood nothing or about nothing how they worked. I looked a long time for any explicative booklet without any appreciable result. I looked also for tank's gunners but they knew only rangefinders with swinging marks(Wandermarke in German).The mystery was clarified when I got a Russian 1 mt. basis rangefinder with mobile marks from which I understood all or almost all. Stereo rangefinder have a great appeal for me. I must also say that the Russian stereo rangefinder used as binocular(I believe it is 12x60) is the more satisfying binocular I ever tried. I don't know much about binoculars (I have read three books about Binoculars the Two Seeger and the Rohan's one and I don't know German at all) but I want learn and Joining you will be a great source of informations. About Italian Binoculars makers I will prepare something next week to submit to Your attention. I am sorry to be not able to express completly and correctly my thoughts in English. Thanks Again, Giancarlo ============================ Subject: Rangefinder From: "R.F.Bolton" I went into a shop today that had the Bushnell in stock so I have some more info on that one at least. The only part that was correct was the price $749.00. They are not binoculars, just look like them at a distance from the front. The model I saw was the 'Bushnell Yardage Pro Laser Ranging System, model 400. It has a monocular sighting system through the centre, with the laser transmitter and reciever either side, hence the binocular look from the front, from a distance. The laser is "Invisible/eye safe Class 1 laser Multi-function". [Thats in the brochure] A LCD display for read out is visible in the monocular sighting system. Magnification is 4x. Uses a standard 9v alkaline battery and has auto shut-off, total weight 18ozs. Size 6-3/16" x 4-1/2" x 2-5/8". Rod Bolton. mailto:brisphotoreps@___.net.au ============================= ====================== Binocular List #60: Various replies. ====================== Subject: Discoloration, Henson From: "R.F.Bolton" Peter, it could well be a 'balsam fault'. Such discolourations are known in older camera lens's also. Dismantling and examining the cemented lens elements should find the offending lens/s. Also with the Henson book, I had a borrow of this book through my local public library. I attatch a copy of the index page to give an idea of the contents. Table of Contents PAGE I The Scope of the Book 1 II How Telescopes Work 5 III How Lenses Work 13 IV How Prisms Work 28 V The Aberrations of Lenses 43 VI The Elements of Optical Design-Magnification 49 VII The Elements of Optical Design-Illumination 60 VIII The Elements of Optical Design-Field of View and Ray Tracing 64 IX The Elements of Optical Design-Eye Relief 88 X Eyepieces 96 XI Mechanical Design 104 XII Collimation 119 XIII The Tools and Materials 138 XIV The Selection of Binoculars and Monoculars 150 XV The Assembly and Disassembly of Typical Binoculars and Monoculars 162 XVI Building a Vest Pocket Prism Binocular 176 XVII Building a Compact Binocular Employing Leman Prisms 199 XVIII Additional Binocular and Monocular Designs 221 XIX The Selection of Spotting and Observation Telescopes 237 XX Building a Typical Prismatic Spotting or Observation Scope 255 XXI Additional Spotting and Observation Scope Designs 276 XXII The Selection of Telescopic Sights 291 XXIII Building Two Big-Game Scope Sights 325 XXIV Two Varmint Scopes and Five More Big-Game Scopes, of Which One Is of Variable Power 347 XXV Building a Target Scope 363 XXVI The Cleaning and Repair. of Optical Instruments, Including the Assembly and Disassembly of Spotting Scopes and Scope Sights 382 Rod Bolton. mailto:brisphotoreps@___.net.au or mailto:bpreps@___l.com ================================ Subject: Re:: Yellow Zeiss prisms and other stuff From: "Bill McCotter" I have in the reject box in my shop, a number of yellow prisms that I replaced from several 6 x 30 military Zeiss binocs and also there are a few from 6 x 30 B & L of the same era. The color is not noticeable when viewing unless a comparison is made with clear binocs. The yellow cast is very noticeable when several are lined up on the bench. After trying every available tool that is supposed to remove the diopter scale ring on the above type binocs (without crushing it), I devised an easily made tool that requires few tools, and works well and is cheap. If anyone is interested, I can I describe it via email. Zack White leather company in North Carolina has considerable leather stock useful in the covering and repair of binocs and cases. Nice people. Regarding the photographic technique, I have used natural light (outdoors) and white reflector board to photograph complicated stuff. A 50% gray matte background with small aperture will yield good contrast and good depth of field. Kodak Plus X and Bromide paper gave superior detail years ago. A little fiddilin' round with stops was required.....I know, I'm living in the past again. Does anyone know a technique to replicate lens retainer rings for ,say, 50mm objectives? I use a Sherline lathe and have to support the thin ring on nylon 66 blanks.....very tedious. Alii Service Notes, Adjusting and Repairing Binoculars, describes a "hand held collimating tool" which is a prism pair with one tinted prism. (p 41) Has anyone seen/used one of these? I am still working on a 1936 Huet tuna can I bought on eBay last year. It has a beautiful prism cell with clever exterior tilt/shift screws. Every optical piece in it had to be re-cemented. The cover screws were filled with solder and the eyepiece tubes were frustratingly thin. Interesting binocs. Bill ======================= Subject: TM9-1580, etc. From: DeutOptik@___m A few notes and errata: i) We are in the process of re-printing several of the WWII (and later) vintage technical manuals on binocular repair, including TM9-1580 ("Binoculars" etc.,) and TM9-1575 ("Wrist Watches, Pocket Watches, etc."). They will be available in the next few weeks and run about $20, for anyone interested. There are several editions of the TM9-1580, and we've re-printed the original 1945 edition. However, a later edition (dated 1953) includes some new information, and we will do a re- print of that one a little bit later this year. ii) Regarding the Bushnell wide field binoculars, this has been accomplished with mirrors (not prisms) and the overall quality of resolution is considered quite poor. We've discussed the possibilities of a better mirrored binocular with Kamekura (the maker of the Bushnell model) and they claim that even marginal resolution over about 6x is currently impossible to achieve, and collimation continues to be problematic. However, we're also hearing whispers that Kamekura has presented an improved mirror binocular to Nikon and Fujinon for possible inclusion in their respective line-ups, a fact which (if true) would certainly indicate an improvement in quality over the Bushnell model. We'll keep you posted. best/Mike ======================= ============================ Binocular List #61: 06 June 1999. Yellow Zeiss optics, phase coatings ================================== Subject: Yellow color in Zeiss binoculars From: HOldenburg@___m Hi there, I've been very quiet since I was invited to join the list - I still didn't get round to write a proper introduction - but I think I can comment briefly on two of the topics mentioned. > Zeiss Porro I glasses from the 1950s. However, many of them are > suffering from a yellow cast to the image. I've got a pair of Zeiss 10x50 Porros which my father-in-law bought in 1963 and a pair of Zeiss 8x50B Porros from about 1966. They're both very good binoculars, although the contrast isn't as good as in binoculars with modern coatings, especially not in the 10x50's which have a simple single-layer coating. Neither of these pairs shows any yellowing, and I've never seen any yellowing in any of the old post-war Zeiss porros I've looked through. There's only one exception: Some military binoculars have a yellow tint because that increase contrast under certain conditions. This tint is very obvious for instance in the military binoculars made by Carl Zeiss Jena, for instance the 7x4040 DF's. Having said that, what I'd do is ask the Zeiss people in Wetzlar about the yellowing you've observed. They're very good, and as far as I know they still offer repairs to virtually all these old binoculars made after the war. I had both the 10x50's and the 8x50's serviced last year, and they still had all the spare parts needed. What I'd do is write to them in Wetzlar asking them about the yellowing and what can be done about it. Make sure you quote the serial number of the binoculars in your enquiry. The address to write to is Carl Zeiss, Kundendienst Ferngläser, Hensoldt AG, Gloelstraße 3 - 5, 35576 Wetzlar They're very helpful and friendly people. Hermann Oldenburg =================================== Subject: Yellow color in Zeiss binoculars From: Atmj1@___m To Peter et al. Being a coward, I try to stay as close to fact as possible. However, I would like to go out on a limb to say that I have heard that the yellow cast is caused by a poor choice of glass for the flint element. I have heard this from more than one source, though I cannot assign a name. The new Chinese Bigeyes -- which are built on an old Zeiss design -- show the yellow cast uniformly, from unit to unit, although they are brand new. Cory adds that if the problem was in the Canada balsam that it probably would not be so uniform even in the same instrument. Bill Cook, Manager, Precision Instruments & Optics, Captains, Seattle =================== Subject: Yellow color in Zeiss binoculars From: "Roger Davis" > I have in the reject box in my shop, a number of yellow prisms that I > replaced from several 6 x 30 military Zeiss binocs Yep, got a few like that myself. I have about 4 trays of 80 prisms from a variety of old binoculars I have worked on over the years. The Zeiss ones are most notable, they have an orange/yellow tint to them. > After trying every available tool that is supposed to remove the > diopter scale ring on the above type binocs (without crushing it), I > devised an easily made tool that requires few tools, and works well and is > cheap. If anyone is interested, I can I describe it via email. I thought that these were a left hand thread, which had a small hole for a "C" wrench?? Or am I thinking of the wrong ones?? > Does anyone know a technique to replicate lens retainer rings for,say, > 50mm objectives? I use a Sherline lathe and have to support the thin ring > on nylon 66 blanks.....very tedious. I made a threaded mandrel to hold aluminium pipe. Every 4mm I machined a deep recess onto the mandrel so that I could part off the pipe once I had externally threaded it. I can do up to ten at a time. You can then put a couple of slots in with a fine hacksaw blade. > Alii Service Notes, Adjusting and Repairing Binoculars, describes a > "hand held collimating tool" which is a prism pair with one tinted prism. > (p 41) Has anyone seen/used one of these? This rings a bell with me. But I am not sure where I saw the reference. If anyone finds out I'd love to see the article. Roger Davis, Binocular & Telescope Service Centre Pty Ltd PO Box 282, Heidelberg VIC 3084, Australia ========================================== Subject: Introduction From: HOldenburg@___m Hi all, I think it's about time to introduce myself to the list. My name is Hermann Oldenburg and I'm in Germany, in Hannover. I've been lurking for a few weeks now, and I'm very impressed by the quality of the discussion here. My own interest in binoculars arose when I first got into birdwatching more than 20 years ago, and ever since then I've tried to keep up to date with new developments. And like most birdwatchers I spend a lot of time trying out other people's binoculars, especially when there are no interesting birds about ...:) Even though I'm first and foremost a user of binoculars, I've acquired some interesting older binoculars over the years. And as I tend to keep all the binoculars I buy I've got quite a few by now (my wife says too many ...:)) My main birding binoculars are the Leica 8x32's at the moment, and in winter I use a pair of Zeiss 7x42's. Among the more interesting binoculars I own are a pair of Zeiss West 10x50's Porros (bought by my father-in-law in 1963) and a pair of Zeiss West 8x50B Porros (~1966). Hermann Oldenburg ====================== Subject: On the effects of phase-corrected prisms in roof prism binoculars From: HOldenburg@___m I'm sure everyone here knows that roof prism binoculars *without phase-corrected prisms* are optically quite clearly inferior to those with phase-corrected prisms. The reasons underlying this problem have long been known. Albert Koenig and Horst Koehler, for instance, mentioned this effect in their book "Die Fernrohre und Entfernungsmesser" (3rd edition, 1959). An excellent explanation was published by Adolf Weyrauch and Bernd Doerband in 1988 in the "Deutsche Optikerzeitung". I got my first pair of roof prism binoculars with phase-coated prisms, a pair of Zeiss 8x30B's, immediately after Zeiss started selling them, and I found the difference in direct comparisons to older Zeiss 8x30's quite marked. It was basically just as Weyrauch/Doerband had written in their paper - better resolution, slightly higher contrast, overall a "more pleasing image". Last autumn I finally had a chance to do a more detailed comparison. We (a couple of fellow birders and I) got together for a weekend trip, and as there wasn't much about we had the time to do a detailed comparison of three different Zeiss 10x40B's. The first one was bought in 1979. It doesn't have T* coatings and the prisms are not phase-corrected. The second one was bought in 1981, with T* coatings but still without phase-corrected prisms,. The third one was purchased in 1998, so it has both T* coatings and phase-corrected prisms. The interesting thing about this comparison was that all three binoculars were of the same make and had the same specifications, so all the differences observed were caused by the different coating technologies used. We compared the binoculars mounted on tripods, checking for their optical quality by looking at birds and a Zeiss standard resolution target in a variety of light conditions. Perhaps the most interesting result initially was that the differences between the two old Zeiss 10x40B's weren't all that great. Sure, the T*-coated pair had slightly better contrast with cleaner colours and a slightly brighter image, but the difference was nothing to boast about. Even under difficult lighting conditions the difference wasn't that great. The resolution was exactly the same (as it should be), and the image of both was slightly fuzzy. This was most noticeable when checking the resolution targets. The comparison with the pair with phase-corrected prisms was almost a foregone conclusion after these results. And sure, it had much better contrast and cleaner colours, a brighter image and quite clearly a higher resolution than either of the two pairs without phase-corrected prisms. In fact, the difference was nothing short of amazing. I believe this comparison puts some of the claims made about modern multicoatings into perspective. Modern multicoantings are nice, but they're not the most important thing to watch out for in roof prism binoculars. Based on this comparison I'd say the most important progress has not been the development of modern muticoatings, but rather the development of phase-correction coatings on the prisms. One other interesting observation we made was this: After we'd done our comparisons I got my old Zeiss West 10x50 Porros (~ 1963) from the car. My friends had got bored with testing optics by that time, so we only did a quick comparison with the new Zeiss 10x40B's, and the results were pretty amazing. Sure, the 10x40's had better contrast and a brighter image, after all, the old 10x50's only have a simple single-layer coating, but the resolution of the old 10x50's was quite noticeably *better*. In fact, the difference was so pronounced that we couldn't help but wonder why Zeiss doesn't make these binoculars with a modern T*-coating anymore. I'm sure they'd beat most (if not all) roof prisms hand down. Hermann Oldenburg ============== Weyrauch and Doerband was also published by Zeiss in English & can be found in Amateur Telescope Making Journal #9, 1996. --Peter =================================== =================================== Binocular List #62: 09 June 1999. More on yellowing, Nikon 10 x 70, replies =================================== Subject: Yellow cast in glass From: DKUHNE@___m I have a comment about the yellow cast seen in the 25-40X100 m.m. Chinese binoculars. I have done ocular replacements on several dozen of these instruments. The yellow cast completely disappears once the original oculars are replaced, so it is not in the objectives or the prisms. The newer models have much less of a yellow cast. I can't help feeling that this yellow cast was planned as a built in haze filter, although orange filters are included with the unit. Also there are two large aperture post W.W. 2 military B&L binoculars that I know of, (one 100 m.m. and the other 120 m.m.), which suffer from this same malady, but in the extreme. The color has gone beyond the yellow and into the pumpkin range and seems to be getting worse year by year. This yellowing is claimed by some to be the fault of certain rare earth materials used in the manufacture of the glass. I have also seen this problem in several of the Schmidt prisms used in the Schneider 25X105 W.W. 2 anti-aircraft binocular. All the best, Kevin Kuhne. ======================================== Subject: Nikon Astrolux 10x70 From: rab .........Nikon design/workmanship isn't what it used to be (by comparison to my robust WF 10x70s): the vinyl(?) covering is not perfectly done and the seam shows conspicuously one side, and there are a few manufacturing blems on the vinyl. They make absolutely no difference to anything, but indicate sloppy work. The binoculars weigh just under 5# (straps missing, and I removed the eyeguards as usual) and are about 2" longer than my older Nikon WFs. The binocs came with two sets of eyeguards: one with greater eyerelief, and another with "wings" with less eyerelief. Since the nominal eyerelief is only about 15mm, I removed them and set them aside. The eyelens is deeply concave, which holds promise of high optical correction, but only about 18mm clear diameter. I have attached my corrective spectaclets with model airplane cement in order to critically examine the imagery. The real FOV is marked 5.1 degs, and the distortion is low but not zero,so I'd guess the apparent FOV is somewhere around 48-deg, not 51-deg. Daytime image quality is excellent! Nikon advertises that they used ED glass in these 10x70's, and the residual image color, when you set the IPD wrong or deliberately moved your eyes around, appears much lower than it does in any 10x70's by any maker, that I've previously used! Second, the image quality does indeed appear critically sharp over the entire FOV; and you know I don't say such things lightly! This is really a wonderful 10x70mm binocular for daytime use, beyond doubt. As determined with a bright white-light flashlight, all the optics, prisms included, are multicoated in these binoculars, and the 'colors' of the coatings look about the same for the left and right sides. Not always the case with other Nikons that I've used. At night, looking downtown on Tucson's city lights, I was unable to see any ghost image for objects within the field of view. I looked at oncoming headlights and at stadium arrays, and I could see no ghosts, not even ghosts involving my cornea (the spectacles, incidently, are multicoated too). Nikon has done a super job on the coatings. HOWEVER, when a very bright object goes OUT of the field of view, top or bottom for sure, there is a strong glare image that comes INTO the field of view. One normally associates this with undersized prisms (and the prisms in these binoculars are small and not fully shielded) or wall reflections. I haven't determined what the source is. Fortunately, there are no 'leak images' that I could discern, those being the bane of many older binoculars, and even some newer ones, particularly the large aperture Chinese imports. Overall, the Astrolux Nikon 10x70's were splendid looking at city lights. Venus shows almost no color; star images are small and excellent over almost the whole FOV, showing only a small amount of aberration toward the edge of the field. The quality is among the best I've seen in binoculars, although it's easier to achieve in the comparatively modest 50-deg AFOV than it is for wide field binoculars. As mentioned earlier, the strong concave surface on the eyelens indicated that good field quality was to be expected, and such was indeed the case. There is a peculiar shading effect on a blank field, which I speculate is due to the combined effects of spherical aberration of the pupil + short eyerelief resulting in a vignetting effect that adds to the ordinary contrast effect (where the bright field abruptly runs into the dark area beyond the field stop). Moving the eye in and out significant affects it, but of course it isn't noticeable when the sky is very dark, although it may still have consequences. Such an effect doesn't seem to occur with my Nikko 10x70 with 7-deg FOV, nor my Nikon 10x70 with 6.5-deg FOV, both of which have more generous eyerelief as well as larger AFOV; yet a pair of aus Jena 'classic' modern 10x50's with 72-deg AFOV but short eyereliief that I recently owned and used showed the effect boldly...so it isn't simply related to AFOV. The effect is give the impression of a bright ring near the field stop. Do you guys have any info on this one? Todd Gross used to grouse about this effect in eyepieces for telescopes. Predictably, I'm sorry that the Astrolux doesn't have a wide AFOV, and dismayed that its eyerelief is short (yet long enough to allow corrective spectaclets to be attached to the eyepiece and still allow the full FOV to be seen thereafter), but I am very favorably impressed with its significantly improved color correction by means of ED glass, and by its extraordinarily well corrected image over the full FOV. The interior metal finish of the barrels and prism retainers could be improved; it's obviously being done on the cheap, and the problem with the out-of- field glare would ideally be examined and corrected. Overall, these are great binoculars! Regards, Dick Buchroeder. =================================== Subject: Parts, roof vs. porro prisms From: DeutOptik@___m (i) Regarding mechanical parts, please note that we have quite a large and growing selection of mechanical parts for old glasss, many in some quantity. We are particularly flush with parts for old US WWII 6x30s and 7x50s, plus assorted Carl Zeiss-Jena models. Anyone looking for retainer rings, diopter scales, etc., etc., might give us a call. Alternatively, try I. Miller & Sons in Philadelphia, another very good source for both optical and mechanical parts. Irv and (son) Harvey can be a bit, well, gruff, but they have an enormous selection of binocular parts. (ii) Also, to the comment regarding the current market bias towards roof prism glasses, we believe here that this is beginning to change somewhat. We understand Leica is working on a line of porro glasses (on the record, Leica is noncommital), and Zeiss is in the process of redesigning its well-known 7x50BGA T* porro model (in our view, the best contemporary porro on the market today). The commercial knock on porros has always been their relatively greater size and weight when compared to roof prism glasses, and roof prism glasses have certainly improved over the last years to the point where the usual advantages of porro prism glasses (e.g., wider and brighter field of view) have greatly lessened. Optolyth's Alpin series of porros has attempted to compete with roof prism glasses by offering a smaller and lighter porro glass with favorable optics, and other than the somewhat narrow field of view, they are a reasonable (and well priced) alternative. We are seeing more activity of late with this line. best/Mike =============================================== Subject: Various From: "R.F.Bolton" ===== "Does anyone know a technique to replicate lens retainer rings for,say, 50mm objectives? I use a Sherline lathe and have to support the thin ring on nylon 66 blanks.....very tedious". I have just gone through this process myself. I could not find a thin wall brass tube that was suitable so I used a short length of thick wall tube that was closest and over/under sized in diameters. Turned it to a suitable size, cut the thread and after checking it would fit, parted it off. To true up the parted end and final finish to length I made a mandrel from aluminium round bar, threaded the same but female, to screw the ring into with approximately half protruding. No problems as it was supported all round in the mandrel. If the mandrel is marked with a punch at #1 chuck jaw it is easy to reset another time and a step on the side touching the chuck jaw means it should run pretty true, at least for cleaning up the retaining ring/s. ======= " Alii Service Notes, Adjusting and Repairing Binoculars, describes a "hand held collimating tool" which is a prism pair with one tinted prism. (p 41) Has anyone seen/used one of these?" I have not seen one but am contemplating having a go at making one similar, but using a semi-tinted/metalised mirror, 50/50 for the beam splitter and a top silver mirror for the other. The front lens's would need to be 63-65mm apart to fit to the binoculars eye lens spacing. The principle of operation, I believe is similar to a camera rangefinder, when all is adjusted the 2 images are superimposed. A coloured filter over one front lens would identify the images. As long as the tool would focus to infinity I see no reason why it should not work. ======= http://www.tranexp.com/intertran.cgi The above site may be of use to members who wish to translate info into english or vice versa. Simply copy that to be translated and paste it into the window on the site. Accuracy is sometimes a bit sus' but the general idea can be understood. There is a choice of options but a look at the site should reveal all. ====== Rod Bolton. Brisbane Photographic Repairs. PO Box 698. Kenmore. Brisbane, 4069 Australia. ========================================= Subject: All American Inventiveness The head mounted, counterweighted, astronomical binocular: http://members.home.net/jharan/ ========================================= =============================== Binocular List #63: 11 June 1999. Radioactive glass, Nikon 10 x 70 =============================== Subject: Radioactive Glass From: Peter Serafin Yet one more question regarding yellow optics: All this discussion on yellow tinted optics has brought to mind an article published in Sky and Telescope a few years ago. One telescope maker mentioned that at one time military optics were made with yellow tinted glass as a built in contrast/haze filter. He went on to say that the tint was achieved when the glass was doped with radioactive elements. A check with a Geiger counter indicated that the levels could be harmful over years of use. The aqueous nature of the eyes makes them especially susceptible. Does anyone have any input on such a hazard? I have some 6X42 SARDs which are definitely tinted in the oculars but do not have a Geiger counter... Pete ======= Radioactive glass is found in a few optical systems from mid-century, including binoculars. I have a text file of clippings from on-line on this subject. Various heavy elements, including thorium, have been used to increase the refractive index of glass, which can cause measurable radioactivity. I have not yet seen any data on whether any binocular or telescope eyepieces contain a hazardous amount of thorium. Needless to say, any reader with information on this topic will find their input to be very welcome. --Peter Abrahams ========================================= Subject: Introduction From: "John S. Platt" As a new member to the list I feel I should introduce myself. My name is John Platt and I live on the gentler side of the Atlantic i.e. the British Isles, in the county of Kent (bottom right hand corner of the island). I am married, have 3 kids, 48 y.o. and retired from a Government job. I have been a binocular enthusiast for many years now having been given a pair when I was 9 and never lost my fascination for them. I have a varied collection, the notable examples being Schneider 25 x 105, Leitz 7 x 50's and B&S tuna cans. I also have a pair with 6 inch objectives with interchangeable eyepieces. I have the Seeger books and am lucky to live close to Terry Vacani who services my binoculars for me. However, having time on my hands, I now intend to learn how to do my own servicing. I am staggered by the depth of knowledge available from all the other listee's and suspect that my participation will be passive for some long time. I look forward to receiving my postings and hope to learn much about this fascinating hobby. Two questions, does anybody on the list live in my part of the world? and second, do any of you have a set of rubber guards for the Leitz 7 x 50 as I have a brand spanking new unused example but with no rubbers guards and I am desperate to get some. Best wishes from a warm and sunny Brasted, Kent in the old country. John S. Platt. ================================================ Subject: Nikon 10 x 70 Astrolux From: "Martin, Dick" A non technical contribution to the 10 x 70 Nikon Astrolux review is in order: I enjoyed my glasses and recognized them as superlative image wise. However, using these fresh out of the box requires a supplementary gas mask to block out what seem to be toxic fumes due to the outgassing odor from the vinyl cover. It was so bad I could not keep them in my office without endless complaints from my spouse... what was she doing in my office anyway? This situation did improve somewhat over a period of 3 or 4 months, but I now use, and am very happy with the Fujinon equivalent and I do not need gas mask oculars. Dick Martin ======== Dick Buchroeder's message on his new Astrolux's contained a note on their stench, but I cut it along with some non-binocular content, thinking it wasn't relevant. But I guess that relevance is in the nose of the beholder. I personally find 'new car smell', vinyl outgassing, and related smells to be very offensive. --Peter ======= From: rab Yes, the Nikons still REEK! At first I thought maybe somebody did a repair job and rebonded the vinyl, but as far as I can see, this is a factory-original. Just noted a slight problem last night: I've been fiddling with taping the rubber eyeguards over the corrective spectaclets, and maybe something came loose, but I discovered that on the LEFT EYE SIDE, the diopter setting is 'off' by more than a full diopter from its nominal infinity value! There are absolutely no signs of anyone having fooled around mechanically or optically with the binocs, which look pristine, but somehow that side is off much more than I would assume could have come from the factory. Nikon just ain't what it used to be, it would seem! Regards, Dick Buchroeder ============ From: Martin, Dick "wondering if you got rid of your Nikons because of the lingering odor?" Sold them on ebay for that reason. I had the Fujinons which I had planned to sell when I acquired the Nikons at a camera show for a microscope and a little cash. The odor was noticable before I put the money up but I thought they would stabilize after a few weeks out of the plastic bag. To me their performance did not warrant having to put up with the odor. The vinyl did seem to be different to the touch although I did not think it was sticky. Its a shame that Nikon has made such a subpar mechanical device; I would think that for the price they would have offered something to complement the optics. The large oculars on the Fuji's are a pleasure to use. Regards Dick ================================================= Subject: perceived brightness at aperture stop seen in some optics In the mail below, Dick Buchroeder discusses an effect seen in the eyepieces of some binoculars and telescopes. Some wide angle eyepieces seem to show a brightening in a ring shaped area just inside the field stop. If you're looking at the sky, it looks brighter at the very outer edges of the field. This has been a subject of discussion on amateur astronomy lists, but as far as I know has not been explained. --Peter ======== From: rab The seller of my Astrolux 10x70 says he owned them for 1.5 years; this suggests its strong odor isn't EVER going to go away! He also said he did not adjust them in any way, so the approximately 1 diopter (negative) setting error on the left eyepiece is either due to something coming loose, or it was never set correctly by the factory. Steve may be able to tell if its the former or the later. I took out my Nikko 10x70 x 7-deg and looked at a blank daylight sky, and I do NOT see the bright donut that I see with the Astrolux and aus Jena binoculars. Also did the test with my 7x35 Swift UWA's, but the fields so wide that it's hard to see the field stops anyway; yet I don't believe I saw anything so pronounced as can be seen on the Astrolux. If you move your eye around the exit pupil area of the Astrolux, you can see the 'donut' of light move around with it; you can make the area (blank field) near the field stop appear to be uniformly bright. The Nikko 10x70 is so marvelously 'comfortable' insofar as knowing when your eye's at the right exit pupil distance, and because it was designed as a Military Glass, and because they may have had help from German optical designers who almost invariably corrected SA of the exit pupil, that it is reasonable to assume the Nikkos are properly corrected for pupil aberration and thus free from vignetting effects from the iris of the eye when it peers straight ahead, whilst the Astrolux, striving for ultimate IMAGE quality quite probably failed to adequately correct SA of the pupil, resulting in vignetting of the field by the iris of the eye, the effect being dependent on the eye's location along the axis. Note that I get cornea-prints all over my Astrolux's spectaclet's because the eyerelief is so short and because it is somewhat ill-defined as to where to put the eye. This too is symptomatic of the existance of SA of the pupil. Regards, Dick. =============== Subject: further on the DONUT From: rab Sorry to be nibbling away at this thing, but it's great sport! I took a careful, closer look at the 'donut' of light in the Astrolux with blank bright sky. One's first impression is that there is a bright ring of light near the field stop. This is an illusion. There is a progressive darkening from where the 'donut' is first noticed in the inner field, increasing toward the field stop. The contrast of the central bright sky, plus the vignetting, plus the abrupt darkness beyond the field stop produces what at first seems to be a donut, but in fact it is a uniformly increasing darkening of the field once the vignetting begins. The combination of Spherical Aberration of the Exit Pupil and the comparatively small( 2 or 3mm) diameter of the human iris during daylight results in vignetting of the outer part of the field of view, and explains the 'donut' effect which is observed with the 10x70 Nikon Astrolux; but the correction of SA of the exit pupil in the older, military 10x70 Nikko results in that binocular NOT SHOWING a donut of light near the field stop. I'm going to take the 10x70 Astrolux to a comparatively dark sky site tonite, just west of Sandario Rd, approximately a 25 minute drive from my house. The sky looks clear, the moon is down, and Scorpio is up! I'm eager to see what these glasses will do with it! Regards, Dick. ========== Subject: dark sky tests with Astrolux 10x70 From: rab I did comparative observations with the Nikko 10x70x6.5-deg and the Astrolux 10x70x5.1-deg last night at a relatively dark site. Both binoculars had presciption spectacle elements, multicoated, attached so that optimum performance for my eyesight was obtained. During twilight, the Astrolux has sharper images, presumably due to its better color correction. Venus, Mars, and the stars appear more compact. As the sky became very dark, however, the difference in optical quality became negligible. I believe this is because my pupil opens up to 5 or 6mm, and its own spherical aberration becomes the dominant source of image degradation. Even in twilight, the 'donut' effect is distracting with the Astrolux, because it cues me to attempt to find a better place to put my eyes to minimize or avoid it; rubber eyeguards to hold the binocs exactly in place would have helped...but the eyerelief is so short that the guards the Astrolux comes with, which can be reversed and held on with tape, make it hard to eliminate the donut and to see the field stops. The Nikko's original rubber eyeguards had deteriorated and had given too little eye clearance for me anyway, so they have been removed and replaced with shallower winged rubber eyeguards bought from Orion. These give just the right amount of eyerelief for ME, and beyond that, they allow me to have some small amount of forward and lateral eye motion to swivel my eyes to peer at the edge of the field, which is difficult or impossible if the eyeguards are too restraining. The Nikkos are very tolerant of slightly inaccurate IPD setting, and of small gimballing of the eyes; there is no donut effect, and no cue to go hunting for a better place to put the eyes relative to the exit pupils. Under dark sky conditions, the larger field of view of the NIKKOS, 7-degrees, is far and away more enjoyable than the smaller field of the Astrolux, 5.1-degrees, and would be the principal reason for choosing one binocular over the other. The comparatively sharper axial images in the Astrolux are a moot issue because of the expanded eye pupil, but the absence of ghosts in the Astrolux is certainly a welcome improvement over the old, partly-MgF-coated Nikkos (cleaned and coated a few years ago, but prisms failed to get included in the coating run). I have not been able to include my 1978'ish Nikon 10x70x6.5-deg in this survey because I have lost my corrective spectaclets for them, will have to commision a new set unless I can find them. Regards, Dick. ============================================ ============================================= Binocular List #64: 29 June 1999. Yellow glass, cleaning, galilean optics ============================== From: "Robert B. Ariail" Subject: Yellow glass I was interested in Kevin Kuhne's remarks concerning the yellow tint in the 25-40X100 Chinese turret binoculars being a possible planned built in haze filter. From the comments made thus far it would appear that both the optics (prisms, flint elements) and the cement may both be the culprits in the older binoculars. The new Chinese binoculars, however could only involve the optics. It may be of further interest to note that the new 15x110mm Russian observation binocular has a distinct yellow hue. Conversly, the Soviet 20x110 Naval Ship's Bonocular provides a crystal, un-tinted view? Since Mike Rivkin has handled both, maybe he has some thoughts on this situation. Bob Ariail ---------- My original post on this subject concerned the very fine Zeiss binoculars from about 30-40 years ago with strongly yellowed images. I've since isolated the problem to the oculars in my 15x60, which is encouraging because it means that it could be a problem in the cement, more remediable than a glass problem. I am writing to Zeiss about this. --Peter ========================== Subject: 20x120 for sale in Florida I received some pictures of what looks like a standard Japanese 20x120, exterior rusty &dirty but not dented, no description of the optics. For sale at an unspecified price, I told them values are about 300 if something is damaged to 1500 if excellent. Dick & Judy Arnold, 905 Wicketrun Dr., Brandon, FL, 33510-2565 --Peter ============================= From: "John S. Platt" Subject: cleaning glass Good evening to you all from the old country. As I start on my new career as a binocular mechanic may I please have your opinions and recommendations on how to clean glass. I have been informed that Isopropyl Alcohol should be used, another said Acetone and a third said a 50/50 mixture of both. So over to you please, what do you use? As I live on the gentler side of the Atlantic, commercial liquids available in the US may not be available here so could you suggest non commercial cleaners. Thank you very much. John S. Platt. ------ From: "John S. Platt" Good evening to the world Due to the increasing costs of using the Internet in the UK I have changed my ISP From now on would you mind using the address xpz67@___rnet.com as they are lot cheaper than the others. Thank you ladies and gentlemen. Best wishes from a very dark and cold UK. John S. Platt. --------------- I use isopropyl alchohol, but when I get a new bottle I always pour some onto a mirror & let it evaporate, to see if there's any oil residue: some drug store rubbing alchohol has oil for the skin. This is not a simple subject, issues range from toxicity to which solvents damage rubber seals. ============================================ Subject: Galilean optics From: Peter Abrahams, telscope@___.com A Russian galilean binocular has been imported recently, white enamel, chromed sheet metal linking barrel to axis, marked 2.3 x 40, 28 degrees. Field is indeed close to 28 degrees, apparent field is about 45 - 50 degrees. The eyecup has an 8 mm aperture. Focused at infinity, the distance between the ocular & the objective is about 40mm, so the objective is probably f1.5 or less, very fast. Mechanical quality is good, coatings look very good, images are good although 2.3 power gives nothing to compare to. I became curious about whether most of the light from the 40 mm objective is wasted when it hits the 5-7mm pupil in your eye. The question is, do galilean optics follow the same rule as the typical keplerian optics: exit pupil = objective diameter / magnification? If so, exit pupil would be 14.2 mm, and well over half of the light from the objective would not enter the eye. The answer is no, but not a simple 'no'. A reply from Steve Stayton follows. ---------------- From: Steve Stayton Funny situation in that the iris in the eye of the observer is the limiting aperture stop in the optical system -- therefore the iris of the eye must be considered to be the exit pupil as well. So the exit pupil is the same size as the eye iris whether it is 3mm or 7mm depending on object brightness (assuming the eyepiece lens on the galilean is at least a little larger than 7mm diameter to avoid clipping the light bundle to the eye). This is why galilean optics always have bright images even at night (also that they have no prisms to absorb light and very few air-glass surfaces). The size of the objective lens does not relate directly to the magnification times exit pupil dia as in a keplerian afocal system. The objective lens dia must be bigger than you would expect in order to have much field of view, in fact the FOV is limited by the objective lens diameter. In a galilean system there is no well focussed field stop to give a clear sharp edge to the field of view -- check it out by looking through one. The edge of the field is seen as the out of focus edge of the objective lens mounting cell. Conclusion here is that brightness is very good in galilean field glasses even uncoated ones (one of the reasons that they remained somewhat popular many years after the introduction of the prism binoc) and that the objective lens diameter must be very large (compared to prism binoc) to allow even a relatively limited FOV to get through. Resulting binoc has good image brightness but small FOV. Hope the above is useful! Steve --------------- I found very little on galilean optics in the optics books, in fact there is more on 'reversed galilean' optics, used in camera viewfinders. This is probably because most optical engineers have no interest in a visual instrument that is as limited in its potential as the galilean is. The problem of field of view is best described in Practical Optical System Layout: And Use of Stock Lenses (McGraw-Hill Optical and Electro-Optical Engineering Series) by Warren J. Smith 1997 $65. Magnification is, as usual, focal length of objective divided by f.l. of ocular. The field of view is limited by the f ratio of the objective. The largest possible apparent field of view is the angle subtended by the diameter of the objective, from the eye lens. The actual AFOV is that angle, divided by the magnification of the system. This makes the limitations very clear, and by drawing on paper the layout, one can see that an f1 objective will subtend 60 degrees of angle from its focal point, and even a modest 4 power will give only 15 degrees of apparent field. To pick an arbitrary limit to a practical objective, an f0.5 lens will give only 22 degrees apparent field at 4 power. These fields are doubled at 2 power, but to me a 2x instrument is more a vision aid for the nearsighted than a useful visual optical instrument. However, hope springs eternal, and there have been some historical highlights in the quest for better galilean optics. Circa 1920, Zeiss tried to optimize the design by making an objective with a low f#, a triplet, but I don't believe they even made a prototype. It was patented & described in Alexander Gleichen, Theory of Modern Optical Instruments, translated from German & published 1921, HMSO, London. He mentions that the calculations can be found in his 'Lehrbuch der Geometrischen Optik', 1902, but I don't think that has been translated. Here is my current annotated bibliography on this subject: Bertele, Ludwig. U.S. Patent 3,663,094. May 16, 1962. Galilean-type telescope system. Air spaced triplet objective, air spaced doublet ocular. Gleichen, Alexander. The Theory of Modern Optical Instruments. (transl. Emsley) London: HMSO, 1921. Hughes, H.A. and P.F. Everitt. On the Field of View of a Galilean Telescope. Transactions of the Optical Society 22 (1920-1), 15-19. Kaichang, Lu; Zhu Yafei, and Kang Songgao. New type of large-angle binocular microtelescopes. SPIE vol. 1527, Current Developments in Optical Design and Optical Engineering, 1991. (Development of Rusinov design.) Kellner, Gustav. U.S. Patent 1,197,742. Sept. 12, 1916. A lens system for galilean telescopes. Doublet objective, bent singlet ocular. Menchaca, Carmen and Daniel Malacara. Design of Galilean-type telescope systems. Applied Optics 27, #17 (1988), 3715-8. Design of 3 systems, 2.2x, 4x, and 5x. Field is not specified but spot diagrams are for a 2.2x with 15 degree field, 4x with 5 degree field, and 5x with 2 degree field. North, John. On the early Dutch (so-called 'Galilean') telescope, and its field of view. Appendix to Chapter 7, First Telescopic Observations of Sunspots. In: Shirley, J., ed. Thomas Harriot. Oxford: Clarendon, 1974. Rusinov, Mikhail. U.S. Patent 4,390,249. June 28, 1983. Galilean-type telescope system. Doublet objective, two airspaced positive meniscus lenses, rear surfaces chosen to provide correction of astigmatism & coma. Ocular is a negative meniscus concentric with objective, with 2 cemented elements of different dispersion to correct chromatic aberration. Magnification is 2.1x, real field is 30 degrees (2(omega) = 30 degrees). Focuses from -3 to +3 diopters. Describes a similar Russian design, using objective with elliptical front surface, telescope corrects for astigmatism, but thick elements restrict field. This is the most ambitious (and hopefully, therefore the most advanced) galilean system I've seen, and can be found at http://www.patents.ibm.com/details?pn=US04390249__ Ryland, Herbert. An Improved Binocular of the Galilean Type. Transactions of the Optical Society, 19 (1918):101-2. (Increased field, using 3 elements, 2 doublets & a singlet ocular. 6.5 power, 5.5 degree field. Variable power model.) Smith, T. Note on the Galilean Binocular. Transactions of the Optical Society, 22 (1921): 84-7. (Increased field, formula for field) =========================================== ============================================ Binocular List #65: 02 July 1999. DO super binocular; Fujinon Techno-Stabi; prices ============================================ From: DeutOptik@___m Subject: Super binocular Thanks for the latest, Peter. A few bits from this end: (i) we always understood the yellow tint on such glasses as the EDF 7x40 and 15x110 Russian glasses to be a high-contrast coating designed to maximize resolution in low or unfavorable ambient lighting. Regarding the influences of cement, types of glass, age, etc. on certain other glasses, I can only defer to your other readers with a more technical bent than I have. (ii) regarding the ideal cleaning solution, some of our OMs swear by a few drops of a mild dishwashing soap in a glass of warm water. (iii) finally, a bit of feedback from your readership about our developing "super binocular" would be most welcome. Our initial feasibility study indicates that about the best we can do while maintaining a 7x binocular would be a 10.3 degree fov, while a 6x glass like the Sard can deliver a Sard-like 11.9 degree field of view. We appreciate that the apparent fields are virtually the same, but we would be interested in any feedback regarding one vs. the other. Our sense is that a 7x glass is more palatable to American tastes, but opinions to the contrary are welcome. In addition, we are considering a design utilizing both mirrors and prisms to reduce the weight and flatten the field, and we believe such a system can be put in place while overcoming the chronic alignment problem of using mirrors. Any particular experience with such a system out there??? Any comments??? best/ Mike --------------------- I would guess that 7x would be more popular, personally I like 6x for the steadier images & wider true field, but only if the images remain sharp over that field. I also believe that at this point in time, mirrors can be effectively used in binoculars. Amateur astronomers routinely use 'diagonals' with aluminum reflective coatings, overcoated with very hard silicon monoxide that is cleanable. These are not very expensive, and quality is far higher than needed with low power binoculars. As noted, mirror can reduce weight; also physical size. Whether the optical properties of the binocular can be improved by using mirrors is an interesting proposition. Prisms used to reflect a fast light cone do introduce overcorrection for spherical aberration; but that is routinely compensated in the eyepiece. I don't know whether it is possible that better correction in the image can be obtained by avoiding the problem by using mirrors. Mirrors would help maintain imaging quality in a binocular that uses replaceable eyepieces to change magnification. The only mirror binoculars that I know of, are not of the quality that a new introduction would require. The Hensoldt Diarex 8x30, sold 1959-60, image is not sharp off axis. The Leitz Amplivid 6 x 24, 1956-1962, 2 mirrors & 1 prism, 12 degree field, good images but off axis not good enough for a 1999 model. The 3 new Bushnell wide angle models, not a model for an ambitious designer. --Peter ================================================= Subject: New Fujinon stabilized binocular Fujinon has introduced a 14 x 40 Techno-Stabi model. 4 degree field, waterproof, nitrogen purged, 13mm eye relief, weight 1300 gm., $1099. It is found at 'Binoculars Etc.' of Stuart, FL: http://www.binocularsetc.com/binoculars/fuji/techno.html The web site notes "digital image stabilizing" with "Dual piezo vibration sensors linked to direct-drive motors", using 4 AA batteries. This model does not appear on the Fujinon binocular web site, http://www.fujinon.co.jp/products/optical/bn01.htm They do have a hand held, stabilized, image intensified Stabiscope 12 x40, described at http://www.fujinon.co.jp/products/optical/bn04.htm See also their 150s at http://www.fujinon.co.jp/products/optical/bn02.htm ================================================= Subject: Historical prices of binoculars Here's a file I started a while ago. Binoculars were very expensive. Any additions? --Peter Prices of binoculars B & L, 1912, prism binoculars: 3 x 12 $40; 6 x 21 $40; 6 x 30 $60; 8 x 21 $40; 8 x 25 $50; 12 x 30 $70; 10 x 45 $75. Ross, 1901, prism binoculars: 8x 8 pounds; 12x 10 pounds. Binocular telescopes (lens erecting system): 5 x 1/2 inch 4 to 7 pounds; 24 x 1 5/8 inch 8 to 13 pounds. Galilean field glasses: 2 to 9 pounds. (Zeiss prism binoculars, sold by Ross: 6 to 11 pounds). Zeiss, 1899, prism binoculars: 4 x 14 130 DM; 8 x 20 160 DM; 12 x 25 220 DM. ========================================= =============================== Binocular List #66: 04 July 1999. DO Super binocular; Techno-Stabi, Broad arrow ================================ From: rab Subject: DO super binocular Mr. Rivkin, my original hope was that you would make an exact replica of the SARD 6x42, which has the merit of my knowing exactly what to expect, at a minimum, when I place an order for one. The concept of "improving" upon the SARD 6x42 (or 7x50 wide-angle analog) is fraught with danger. There are hundreds of half-baked binoculars for sale, many of them no doubt intended to improve in some manner upon earlier designs. My own observation is that things generally run down-hill when people try to 'improve' on an earlier design, despite good intentions. I've owned two SARD 6x42, and while they were interesting and even useful, the power is lower than I like. A wide-angle 7x50 such as B&L produced in WW2 would make me happier. I would be willing to review the optical design before you manufacture it, holding the details in strictest confidence of course. I would also be willing to comment on mechanical details, although there are others better qualified than I to do that. Sincerely, R.A. "Dick" Buchroeder, PhD (optics), professional lens designer. ========================================= Subject: DO Super binocular From: Nelson882@___m This is my first comment to your binocular discussion group, I will later introduce myself more formally, but I wanted to comment on Mike Rivkens' developing "super binocular. Perhaps I haven't read all the comments up to this point, but the use of mirrors should be avoided in a binocular because of the multiple reflections required to invert the image and the consequent light loss. As far as I know, Aluminum reflects less than 90% (?) of the incident light which is not a problem in a one surface telescope diagonal but would be a problem with four or more reflections used in a binocular. Another issue is the spectral efficiency across the visible region. Most telescope users are more interested in resolving points of light rather than seeing an image rendered as close to reality as possible including all its color components - this is assured using glass prisms with total internal reflection between 400 and 700 nm. but is it assured with the use of metallic reflective films? As far as the choice of power, most buyers today unfortunately under rate clarity and sharpness in favor of numerical magnification and although I enjoy the use of 6x glasses the market would be increased if the power were 7 or preferably 8x. 8x glasses can provide wider fields with the same size prisms because of the shorter focal length of the oculars and the consequent use of shorter focal length objectives. Wouldn't it be wiser to make a 12 degree 8x glass and really push the apparent field to new and higher ground? Steve Nelson ------------------------ I had thought that modern aluminized coatings were well above 90 percent reflectivity, but when I read my references on this subject, I found that new, overcoated aluminum coatings can be 96 percent, after a year or more they degrade to about 90 percent or less. I'd appreciate a correction on this, if I'm wrong; and any information on the reflectivity of aluminum over the spectral range of visual light. There are dielectric coatings that are permanent and about 99 percent reflective, but they are applied in a very complex process and