Over the course of time, the 7 x 50 went through the developments seen in other service glasses. The Zeiss models retained the use of aluminium (body), zinc and brass as the predominant materials through W.W.I. In the thirties, aluminium became more established for all metal parts, and the field glasses become lighter. Leather and hard rubber coverings disappeared over time, and the German military and Navy models had a black, more or less thick laquer. A coarse lacquer was used before the first World War (Fernglas 09, see fig. 9, and some Hensoldt models). Leather replaced hard rubber at the end of the first World War, because of the shortages of rubber.
In the time before the second World War, and even more during the war, several construction forms or variants of the 7 x 50 were produced. The main danger at sea was the hazing of the optics from the intrusion of humidity, and this was countered with a built-in dessicator cartridge. Fig.223 shows a freqently seen variant of the Zeiss 7 x 50 Marine model where the bottom covers of the prism housing have such a cartridge screwed into them. The ocular of this model has the usual construction form.
[page 333] Equally common are the 7 x 50 models with "arrangement for use with gas mask", see fig. 224. The special ocular construction of this glass is recognizable by the hard rubber ocular covering, attached to sliding rings. The exit pupil is longer in this model. As mentioned in section 2.5, the Zeiss 7 x 50 models with gas mask oculars were also used for anti-aircraft defense, and perhaps by the Navy. Surviving models are marked "M IV/1" and "T", and with "Flak.(Kueste)" [coast] or "Scheinw. u. Fluwa." [searchlights and anti-aircraft arms”. Field glasses of this kind might have been used with anti-aircraft search lights, for there are pictures from W.W. II showing field glasses which are mounted on a horizontal strut next to the searchlight.
Another Kriegsmarine 7 x 50 from Zeiss, is similar to the usual Binoctar, it is a 7 x 50 with neither desiccator cartidges nor gas mask oculars. This relatively rare glass in shown in fig. 225.
An unusual German 7 x 50 field glass is shown in fig. 226. It is a fixed focus model. the oculars do not have any screw threads for focusing. This characteristic indicates use in a military airplane, but the coating indicates use in the Navy. We can only speculate about the exact use, or area of use during the war. These German military 7 x 50 fixed focus models are rare, the auther knows of only the two depicted examples, both from Zeiss.
[page334] Only a few specimens survive of another German 7 x 50 model from the Kriegsmarine. This is a model with eyeguards that can be folded to the side, which permits easy cleaning of the eye lenses or use with glasses or gas masks. The model in fig. 227 (top) is furthermore distinguished by an ocular lens which sticks above the housing by about a millimeter. These two characteristics can also be found in the U-boat glass of fig. 254.
There were accessories for the Navy 7 x 50s, but only photos survive. Frequently these glasses were protected with a rubber covering, which was pulled over the housing, see fig. 228. The rubber was sensitive to sweat from the hands, fat and oil, and it soon became sticky, disintegrated and lost its durability. Today no (?) example of this accessory survives.
A field glass is only truly complete with the original case. The case for the 7 x 50 with gas mask oculars can be seen in fig. 224. This case contains further accessories, such as glass filters which can be attached on top of the eye pieces.
As a couple of the members know, I am trying to learn how to refurbish old post-war Japanese binoculars as a hobby. I have encountered several difficulities, and I was hoping that someone in the group could point me in the proper direction, to wit:
Does anyone know where to obtain the textured vinyl wrap used on the older glasses?
Where could I get lenses and prisms re-coated, and what kind of expense should I expect? I have found several pair of old glasses that seem possibly worth the effort and some measure of expense.
One of the earlier lists had a comment, and I apologise for non-attribution, as I can't find the specific reference right now (boy, that dragged out!), to collimating the BARRELs by manipulating the hinge. Could whoever mentioned this please expound a bit. All of the (admittedly cheap) glasses I have worked with have a rigid hinge.
In list #81, Cory Suddarth discussed desiccants. In the past, I had found these hard to come by, and I was re-cycling them in the oven. However, I found a very economical source for quantities of these; they can be bought in lots of 50 bags for about $12. Each bag is estimated to treat 400cc of space. This makes them cheap enough to trash when fully saturated. The site is www.archival.safeshopper.com.
I am all with Brian Haren in looking for books. The one by Seyfried is a very good primer, but does not touch on the actual optical properties. But it will certainly get one started tearing binocs apart.
In list 83, there was some discussion about greases and the laments that they were not sold in small quantities. Nye Lubricants makes a heavy silicone based grease, NYE PG-8s, (thanks to DeutscheOptiks for the info on the grease) that can be purchased in small (2 & 4oz jars through TAI Lubricants at about $35/2 oz). The number is (302) 326-0200. Nye also makes an excellent penetrating oil. I had been soaking a lens assembly in normal penetrating oil for 4 weeks to loosen a retaining ring. To no avail. I used the NYE Film Wet 200, and a couple of days later, wallah! And, yes I tries it on some other items that had not been previously soaked and it worked just as well. I hope this info is of some use. Gene Harryman
There are a few binoculars that are collimated at the hinge, the newer Rolleis are one. The smallest adjustment would have a large effect on alignment, so I'd imagine it is a difficult process. --Peter
Subject: ND glass transmits IR. Danger!
I examined the Schott Glass Filter catalog, for Neutral Density glass, types NG, and ALL of them have high transmission in the Infrared, peaking around 2.6 microns, and should therefore be regarded as DANGEROUS FOR SOLAR OBSERVING!
.....(you can) block the IR by adding KG5 heat-absorbing glass(the Schott Catalog confirms it!). The KG5 is reasonably 'white' in the visible, so you still have an ND filter but a safer one. Regards, Dick
Subject: Identification of a small opera glass
From: "Roger Davis"
A couple of years back I had a small pair of brass opera glasses come into my hands. Fred Watson said they were "exqusite". They are (when closed) about 40mm high OG O.D. 32mm approx 3X magnification 3 telescoping sections with the final 4th section being the focus tubes. When you push a small button on the OG end, the sections spring open. Expanded height is (at focus) 75mm. Markings: BREVETTE S.G.D.G.
Any ideas?? Roger Davis, Binocular & Telescope Service Centre
Non frustra signorum obitus speculamur et ortus. (not in vain do we watch the setting and rising of the stars)
(SPJP Societe Parisienne Jumelles a Prismes) --Peter
Subject: A second look at the Zeiss Victory 8x56
Last weekend I had a chance to have another look at one of the new Zeiss Victory 8x56's, this time in the field. I compared it to a pair of Zeiss 8x56 Classics and a pair of Leica 8x32's for about an hour and a half, and in this comparison it blew the other two pairs clean out of the water.
The resolution of the pair I used was very high and the contrast just about the best I've ever seen in any pair binoculars. Colour rendition was also excellent with natural, saturated colours, even in difficult light conditions when viewing against the light. In fact, the optical performance was so good that I'm seriously considering getting a pair even though the 8x56's are for my puposes definitely on the heavy side.
Why there was such a difference to the first pair I looked at a couple of weeks or so ago I don't know. I'm normally pretty good at judging the quality of binocular optics. Zeiss binoculars are normally all virtually identical in their performance, so I think maybe that pair was somehow damaged after it had left the factory. (Some cynics over here say all parcels labelled "Fragile" are dropped at least three times before they reach their destination ... .)
Onto the other points: I still didn't like the focussing all that much, but it didn't bother me all that much in the field. I think I could get used to it. The handling is amazingly good for such a relatively heavy pair, it's exceptionally well-balanced and I found I could use it for extended periods of time with no fatigue. In fact, I found it easier to use than the Zeiss 8x56 Classic. The eyecups take some getting used to, but after some fiddling around to find the ideal position I found them pretty comfortable.
I'm now very much looking forward to the 8x40's and the 10x40's. Hermann Oldenburg
Subject: East German Binoculars
From: Thomas Press tpress@___le.edu
I thoroughly enjoyed your commentary on post-war Zeiss Jena binoculars in the recent Binocular List - very perceptive and exceptionally well-written.
I have owned over the years an 8 x 30 Deltrintem, 7 x 50 Binoctem, 7 x 40 EDF, and 10 x 40 Notarem (all,thankfully, now in the hands of new owners), and was ultimately disappointed by all, chiefly for build quality deficiencies. Optically, I thought the 7 x 50 was the best of the bunch. I may have lucked into a good sample, but I found the 10 x 40 to be OK by non-phase coated standards, i.e., similar to an Optolyth 10 x 40 Touring model or even an early 80's Zeiss 10 x 40 Dialyt, but the internal focussing mechanism of the Notarem failed, and the instrument never seemed as clear following the warranty repairs. I am still mystified why the 7 x 40 EDF continues to get rave reviews and fetch nosebleed prices: I could never get used to (or appreciate the benefits of) the yellow images, and find the still-available IOR Romanian 7 x 40 porro military glass to be dramatically sharper (perhaps its design was influenced by the Zeiss Jena Septarem model you mentioned). Best regards - Tom Press
Antoni M. Piaskowski: "Dawne Lunety I Lornetki w Zbiorach Polskich" (Old Terrestrial Telescopes and Binoculars in Some Polish Collections), Retro, Warszawa, 1996. ISBN 83-901353-7-X (~200pp).
In case you're not familiar with this book, it is Professor Piaskowski's optical and metrological survey of 97 old instruments, of which 37 are Galilean binoculars and 10 are prismatic binoculars (mostly well-known types). Except for summaries in English and German, the book is in Polish. The publisher's address is Wydawnictwo Retro-Art, Warszawa, ul. Emilii Plater 25. Best wishes, Fred
Subject: British patent information
From: Peter Abrahams
The British magazine 'New Scientist', 26 Sept. 1992, vol. 136, number 1840, page 21, has a story about a very interesting British patent binocular:
Michael Freeman of Optics & Vision, Clwyd, Wales, (patent WO 92/5462). This binocular uses curved mirrors instead of prisms. The optical path is Z shaped, and the eyepieces are weaker than usual, allowing increased eye relief. "The aperture can also be a slot so that no adjustment is needed for the spacing of the user's eyes. The mirrors can be folded down to fit the binocular into a flat package."
Can anyone look this patent up, and perhaps scan it into an electronic image?
Neither Freeman nor Optics & Vision appear in US patent searches. Thanks, Peter
From: "Bill Cook"
>Does anyone know where to obtain the textured vinyl wrap used on the older glasses?<
I get mine from Fargo Enterprises.
>Where could I get lenses and prisms re-coated, and what kind of expense should I expect?<
Sky and Telescope Magazine will show a number of coating houses. I most recently used Uvira in Oregon. I can't remember the cost. It is important to remember that coating takes place at HIGH temperatures and no coating house guarantees against breakage.
>to collimating the BARRELs by manipulating the hinge. Could whoever mentioned this please expound a bit. All of the (admittedly cheap) glasses I have worked with have a rigid hinge.<
I have repaired and restored thousands of binos. I have never seen one collimated at the hinge.
>The one by Seyfried is a very good primer, but does not touch on the actual optical properties. But it will certainly get one started tearing binocs apart.<
Please read that last sentence three times, fast, before proceeding.
Greetings from sunny San Diego, Peter. A few (belated) thoughts and comments from your previous missives:
(i) the glass polarizing filters for Steiner military binoculars remain in stock, and they are NIB @___air (including mounting hardware);
(ii) regarding our Swiss Leica 8x30, there will be a review of these in an upcoming Shutterbug magazine by editor Bob Shell;
(iii) with regard to locating leatherette for recovering binoculars, there are several catalogues offering camera repair equipment and supplies and they all offer such leather coverings. If interested, e-mail us for particulars;
(iv) additionally, there have been several comments regarding the availability of binocular collimators, and please note that we continue to have 2-3 of these available. Due to their few numbers, they are no longer shown in our catalogue, but they are the British field service type and work for almost any hand-held glass up to about 70mm aperture. The damage is $999, including a fitted mahogany box, selection of books on optical repair, Geneva gauge (for measuring lens curvature) and an assortment of binocular bodies and parts.
(v) we've recently received a sample of a Bosnian-made binocular (from Sarajevo) that is substantially identical in form and perfomance to the Carl Zeiss-Jena DF 7x40 (our so-called "Checkpoint Charlie" glass). Pricing is attractive and it seems to be an excellent instrument (albeit somewhat heavy, as with the DF model). Anyone know anything about that?
(vi) Finally, we have been advised by several of your readers that our Czechoslovakian 10x70 as listed in our latest catalogue is actually a 10x80, and thus we stand corrected regarding same. It's basically a knock-off of the WWII German flakfernrohr glass but appeared to us to measure smaller than 80mm. However, if your readers say it's an 80mm objective, so be it.
Oops, one more thing. We are looking to add a couple more reprints of military technical manuals to our Optical Bookshelf listings in the fall, and I will advise particulars when those are ready. Notably, those were not listed on your latest bibliography, and we find them to be extremely useful. I might also note the new Koblenz circular that also offers some noteworthy information about the very good optics collection in the Koblenz Technical Museum. It's in German, but still very worthwhile as a reference. All the best, s/ Mike Rivkin, Deutsche Optik
Subject: French terminology
From: Fred Watson
I'm pretty sure S.G.D.G stands for "Sans Guarantie du Gouvernment", referring to the terms of the patent.
(Can't check as I'm away from home at the moment...)
Cheers for now, Fred
Binocular List #117: 08 July 2000.
Subject: sgdg comment.
S.G.D.G Is indeed: Sans Guarantie De Gourvenment; literally: without the guaranty of the government...
It has a juridical meaning: It tells that the item on which it is inscribed, is patented ( or model protected), But that the government is NOT obliged to do anything about patent (or model) infringements...
Meaning that the owner of the patent has to pay himself in case of a trial...All the government does, is to record the patent (or model)...
It can be, that it refers not to a patent but only to the actual item (model protection)....meaning that a direct copy will be an infringement on the producers rights to his design...
Here in Denmark we can take out a patent OR protect the design.... Mønsterbeskyttet...(model protected)
The german counterpart....DRGM.....means Deutsche Reich Gebrauch Muster, literally German nation use model...meaning this model is protected against copies within the german nation.
After world war 2...around 1953 the new term was. DBGM....Deutsche Bund Gebrauch Muster....same thing, only it reflects the change of state from a Nation to a union of states...the Bund der deutsche länder. Still in existence....!
Generally these markings, be they french or german, can be taken as a sign of some quality.....it Does cost money to get the recording papers....but not much......and Model protection is cheaper and less easy to defend in a trial than real Patents....
DRP is Deutsche Reich Patent...and DBP is Deutsche Bundes Patent...and these are patents....
There MIGHT be a Sans Guarantie de Etat as well......SGDE....either this is the belgian version or it is a certain french version for some special purpose....it can be seen on preWW1 guns from the Belgian Fabrique Nationale gun factory....mostly mauser and browning guns.....
But as far as I know there are few belgian bino producers....
Michael Simonsen Copenhagen Denmark
Subject: ND Glass
Although Mr. Bolton's heart is in the right place, it is totally inadvisable to use such 'heat absorbing' glass and expect it to provide any eye protection whatsoever for solar viewing! The 'heat absorbing' material used with slide projectors and other non-critical applications is merely iron-rich crown glass and while suitable for extending the life of your transparencies, won't do a thing for your eyes.
One should have a spectral transmission curve out to 3 microns wavelength or more in order to determine the usefulness of a filter material. The Schott glass that was recommended to me by a solar expert, David Lunt, has been proven suitable for the purpose. Be wary of substitutes! Regards, Dick Buchroeder
Can someone explain the origin and meaning of the various names for the Zeiss models? Is it linguistic, or gibberish? Is there some sort of rule/code for deciphering something about the specifications of the binocular from the name? Thanks from a novice collector, Dan Weinstock Geneva, New York
My understanding is that they are just words that prevent confusion during cable transmission of orders.
In the1920s, Zeiss used product names beginning with A, in sequence from Asa to Ase. But whether there are exceptions, or how the sequence overlays product lines, is a topic I'll leave to others. Peter
From: "Brian Haren"
I came across a WWII vintage 7x50 today (M16) and took a quick look down the objectives. Yuck. Lots of what I think is fungus - kinda' spider web-like and spreading across the prisms and probably the inside surfaces of the optics. The exterior glass seems in pretty good shape, just could use a cleaning. Question - what permanent damage does fungus do to the inside of a binocular and does it's presence generally render the bino's unsalvagable? What treatment should I use on the inside of the bino's to make sure I kill off all the critters? If I can get my hands on these at a reasonable price they look like they'd make a good "starter" bino to try my hand at servicing, but only if they are worth resurrecting. Thanks! Brian
Fungus etches glass & repair usually requires repolishing, which strongly tends to alter the optical qualities of the system. Prevention involves keeping them dry.
Is there a chemical that prevents fungus?
There's some discussion on fungus in list 96, found on my web site. --Peter
Subject: 19th century Galilean binoculars
I continue to be frustrated by the lack of available documentation on 19th century non-prismatic binoculars, and I envy you fellows with the abundance of historical and technical information on the later items. French instruments so dominated the market during the mid-19th century, that I can not help but think that such a significant industry is not documented some where. I am planning a trip to Paris next summer on other business, but I would like to use the opportunity to see what information might be available. I wonder if anyone on your list might have a contact in Paris. In fact, I would be willing to hire someone, possibly a graduate student, to do some preliminary research in France. Don Wilson
The French were certainly the most important makers of opera & field glasses, and there is very little information on them. I've been told that the two World Wars were particularly devastating to French optical firms because they were appropriated by the conquerers, and because many were owned by Jewish businessmen. I don't know if this is accurate. There is an additional factor in this problem; the French government, which is reputed to be a very difficult bureaucracy, and not sympathetic to foreigners. --Peter