Zeiss: Collection of cross-section and cutaway images (1 Viewer)

John A Roberts said:

C) Post-WWII Oberkochen Designs - not CZJ
For comparison with A) above, see the images showing the 3 patterns of optical construction used on the the new West German Zeiss 8x30’s introduced after WWII
at: https://www.birdforum.net/showthread.php?t=384860 , see posts #5 & 6

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I have forgotten this one, in relation with post #5:
Zeiss Porro 8x30 B, first version.

Jean-Charles

CZJ post-WWII Roof Prism Binoculars

Following on from WWII, the original Zeiss location in Jena was in the newly created nation of East Germany
Binocular production recommenced using both the CZJ brand and pre-WWII Zeiss designs

A new independent company also using the Zeiss name and staff was established in Oberkochen in West Germany
When it commenced binocular production it used entirely new designs (see part C) in post #5 above)

The companies operated independently until 1991, when parts of the Jena one were united with the Oberkochen one, following the 1990 reunification of Germany
Another company Docter-Optic took over the factory in Jena and continued to manufacture some of the models previously made there *
(see: http://www.company7.com/zeiss/history.html and the attached information from an earlier version of the DO website)

* correction: DO acquired a CZJ factory in Eisfeld (see post #65 below)

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So far all the roof prism models illustrated in this thread were made at Oberkochen. However, by the late 1970’s CZJ in Jena also commenced roof prism production

The roof prism line comprised three models:
- Notarem DF 8x32 B
- Notarem DF 10x40 B
- DF 7x40 B GA/ EDF 7x40 (commercial version/ East German military version)

The first two were centre focus models that shared a common body and optical design and were intended for commercial sales
The last was an individual focus model, differing significantly in detail and primarily intended for military use
All three used Schmidt-Pechan prisms


A) The Notarems
As previously indicated, Holger Merlitz’s site has a variety of CZJ catalogues including ones from 1980 and 1985, along with a Docter-Optic one from the early 1990’s
at: http://www.holgermerlitz.de/binoculars_english.html

The 1980 catalogue includes both the Notarem models. See three images from it:
- the basic details of the two models
- a closeup of the 10x40’s optical construction
- a picture of the two models

As can be seen they are readily identified by their squarish shape and the combined focus and diopter control in the centre of the main body

The 1985 catalogue indicates they were also available with a RA finish. See an image of:
- the 8x32 from: https://www.ebay.ca/itm/254248123346
- the 10x40 from: https://www.opticalrepairs.com/notices.htm

After 1991, Docter-Optic continued to manufacture the two models with upgraded RA coverings, improved lens coatings, and an aspheric lens in each side of the 10x40,
see the attached images

And the 8x32’s were also once marketed by Rollei, see the image from: https://www.astroforum.nl/forum/instrumenten/verrekijkers/1318558-quizvraag-van-wie-is-deze-kijker

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Images in the 1985 catalogue clearly indicate that both models use the same optical construction
The 10x40 has a longer objective tube and larger diameter lenses

yovo has posted 5 images of a disassembled 8x32 at: https://www.birdforum.net/showthread.php?t=311125
They show in order of disassembly:
- 1 image of the front of the main body with the two objective assemblies removed, showing the two prism mounting plates
- 3 of the removed prism assemblies on their mounting plates, and
- 1 of the inside of the main body, showing the focusing mechanism

It would seem that the design is based at least in part of that of the Leitz v2 Trinovids
See the flow of 5 images of the 7x42 version by Frank/ wpg (also known on this forum as LPT) at: https://www.flickr.com/photos/binocwpg/8103356727/in/photostream/
The Notarems appear to focus by movement of some of the eyepiece groups, as was the case with the original Leitz design


John


p.s. I’ll post separately about the 7x40

And the additional images . . .

John A Roberts said:

The companies operated independently until 1991, when parts of the Jena one were united with the Oberkochen one, following the 1990 reunification of Germany

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Could you elaborate on that? I can't imagine what Zeiss (West) would still have been interested in and am unaware of any such connection, having read only of the separate history of Docter in Jena/Eisfeld after 1990.

Hi Tenex,

I based that on this portion of the Company7 history (the text may have been translated into English, or written by someone with English as a second language, but the main points are clear) . . .

And re-reading it, there is a correction to be made: DO took over a CZJ factory in Eisfeld, rather than the main one/s at Jena


John

This is a great thread! Thank you very much for posting all the internal photos. Here is my contribution: Leica Duovid. Note the spiral cam system in the eyepiece. It is the same mechanism used in riflescopes for providing zoom.

John A Roberts said:

I based that on this portion of the Company7 history (the text may have been translated into English, or written by someone with English as a second language, but the main points are clear) . . .

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Thanks for that. There was also another company "Analytik Jena" that I (apparently wrongly) assumed had been formed out of the CZJ Jena facility. Does anyone know what Zeiss has been doing with it, with so many fewer workers?

I recently saw on my public TV station the final series of the German show "Weissensee", which began in the 1980s DDR and concluded with just these economic pains of reunification: problems of privatization, uncompetitive Eastern factories, unemployment and so on. It was good practice for my German, picking up new words like verarscht.

How about "The Binocular of the Century" the Nikon WX 7x50 and 10x50. Possibly the best binocular ever made.

henry link said:

Also the green binocular in Lee's post # 23 is one of the 42mm FLs, not a 56mm. The 7x can be eliminated by the objective barrel length, but we can't tell whether it's the 8x or 10x.


Henry

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The green binocular in the cutaway is the 10x version of 42 FL - the 8x has a larger aperture at the rear of the ocular assembly.

I have a couple of these (green and black) which are both the 10x so I assume that a batch of 10x42s were used to produce the cutaways.

PS.... I remember in the 1980s at Leica that one of the final tasks for an engineering apprentice was to make a cutaway binocular as a demonstration of their new skills.

Gary.

Thanks Gary.

I'd like to make a suggestion at this point that would give this thread at least some loose semblance of organization. Since the first three pages have been devoted almost exclusively to Zeiss cutaways perhaps it would be best to wrap up what we have left of Zeiss material before moving on to one of the other brands with many available cutaways, like Swarovski, Leica or Nikon and then on to brands with only one or two cutaways.

I found a couple of more Zeiss images among my stuff. The first is a partial cutaway of an eyepiece and prism which I think comes from one of the original Hungarian made Conquests. It so closely resembles the 8x30 Dialyt that I wonder of the 8x30 Conquest was based on the Dialyt design. Hopefully somebody else can find the whole thing so we can see if the Conquest used a moving objective for focusing like the Dialyt. The second image is Kohler's patent drawing of the optics of the 8x30 W Oberkochen Porro. I also included an illustration of the the complete binocular.

It's interesting to compare the 6 element Kohler eyepiece from the old Zeiss 8x30 W to the eyepiece used in the Nikon WX from post #68. Unfortunately, Nikon doesn't bother to indicate cementings, but if we assume that the field and eye lenses of the Nikon are cemented doublets then the main body of the eyepiece appears to be a version of the 6 element Kohler with the addition of a (probably) triplet Barlow/Smyth group placed ahead of the eyepiece fieldstop. I've read that the Kohler design is also the basis of Televue Panoptics.

Here a layout of the Zeiss 7x50 U.D.F. Porro II design, made between 1938 and 1945.

Can the Duovid be used at intermediate magnifications, besides the two marked?

There are cutaway drawings on the sides of some Nikon binocular boxes.

There are also cutaway drawings on the sides of Russian and Soviet scope boxes.

So one would need to photograph these and post images, which unfortunately I don't do.

With older optical devices, the curves of the elements were sometimes modified to account for different batches of glass. Or the spacing changed.
With modern glass I suppose the chemistry is much more exact and modification isn't necessary.

Although I found it hard to believe, I was told that 48 inch f/8 aerial lenses were bought back from scrap dealers.
They were returned to the makers, the glass identified exactly and the curves measured. Then the details were fed into a computer.
The spacing of the elements was then optimised.
In some cases the resolution was increased 8 times compared to first measured when bought back from the dealers.

The reason this was done is that in modern terms, new lenses were £1 million.
The old lenses cost £75 from the dealers.

Regards,
B.

Binastro said:

Can the Duovid be used at intermediate magnifications, besides the two marked?

Regards,
B.

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Although I have been told several times that Duovid will not zoom, one owner and user of both Duovids says it is possible but it is 'tricky to get both barrels on precisely the same magnification'.

Lee

John A Roberts said:

p.s. there was also a monocular version. I’ve attached the specifications from a November 1998 catalogue which shows both- it also shows the spec’s for other products of the period including the Design Selection series

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I've actually got the Zeiss 20x60S Mono ... Does anyone have a drawing of that model?

Hermann

garymh said:

The original Conquest has a moving internal lens which looks like the focussing lens on an FL but actually acts as an objective. What looks like the outer objective is just a flat glass protective feature.

Gary

Click to expand...

Thanks again, Gary. Can you tell if that eyepiece/prism cutaway belongs to the 8x30 Conquest?

Earliest Porro Prism Designs

I’ve been occupied with a number of matters for the last couple of weeks, but now have a chance to finish posting on the optical construction of Zeiss binoculars. So . . .


While Zeiss commercially introduced Porro prism binoculars in 1894, it was not the first to use Porro prisms in either binoculars or other optics
e.g. see a short history of prisms in binoculars starting from post #28 at: https://www.birdforum.net/showthread.php?t=378895&page=2

By 1894, the basic optical designs for both objectives and eyepieces were well established
The main limitation was, that as there is up to 4% light loss by reflection from each uncoated glass surface, designs tended to minimise the number of seperate glasses in optical devices
i.e. to balance a sufficiently bright image against better optical performance
(it was not until after WWII, with the widespread adoption of single layer lens coatings that reduced reflection to around 1% per surface, that more complex designs were increasingly practical)


Available Images
While there are only a limited number of images showing the optical construction of early models, they do include some very early examples:
- a cross-section from the original patent, see: https://www.birdforum.net/showpost.php?p=3914041&postcount=30

- a drawn cut away image from an early advert (from before 1900?), and

- two photos of a cut away 8x20 unit dating from 1896. The first is from Zeiss at: https://www.zeiss.com/corporate/int/about-zeiss/history/technological-milestones/binoculars.html ,
and the second from: http://onlyzeiss3.web.fc2.com/rep-yukari/rep-z06obk_opt03.htm

The 8x20 binocular appears to be the same one that’s on the cover of the Spring 1990 issue of the Zeiss Historica journal, see: https://issuu.com/zeisshistoricasociety/docs/pdf-zhs-journal-spring-1990

n.b. there is a particularly clear photo of another early cut away unit at Alamy but it requires payment for use, see: https://www.alamy.com/stock-photo-cross-section-detail-of-a-pair-of-1930-binoculars-29842518.html

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In addition, for both more detailed images and explanation of the construction of some very early Zeiss Porros, see both:
- a 3x18 unit #53 at the Vacani’s website: http://www.binoculars-cinecollectors.com/html/body_unusual-optics.html , and

- a 6x15 unit #306 and an 8x20 #4,976, in the paper ‘300 Year Quest for Binoculars’ by Greivenkamp and Steed at: http://fp.optics.arizona.edu/antiques/Quest for Binocs - SPIE.pdf


Optical Details
In general, the earliest Zeiss Porro prism binoculars follow a simple pattern of:
- a cemented doublet objective (2 glasses in 1 group)
- a single field lens and a cemented doublet eye lens for the eyepiece (3 in 2), and
- two seperate Porro Type I prisms (2 in 2)

So as there 5 groups and therefore 10 surfaces, there was potentially a 40% loss of light transmission due to reflection alone
[EDIT: Binastro quite rightly addresses this oversimplification in the next post. However, bearing in mind all of B's comments,
also see Gijs' measurement of the performance of an uncoated Marine Glas from 1896 in post #80]


What’s most interesting is that the while the binoculars use Porro Type I prisms, the prism pairs are spaced as far apart as the housing allows (as in the original 1893 patent image)
Greivenkamp and Steed note that the separation of the prisms in the 6x15 model is 20mm (0.8”), and in the 8x20 model 30mm (1.2”)


As can be seen from the images there are extensive efforts to control stray light:
- all of the internal surfaces are blackened
- the sides of the prisms also seem to have been blackened, and
- there is a tube with interior baffles, that connects the eyepiece to the eyepiece prism

In addition, on at least some models, the objective lenses are so deeply recessed in the housing, so as to be behind the front prism


An Exception
The very early unit #53 shown on the Vacani’s site is atypical in several ways, including:
- the objectives comprise 4 elements in 2 groups (to minimise image distortion), and
- there is an additional tube connecting the objective to the objective prism (a stray light control measure)

That Zeiss experimented with different approaches so early on, is of course not surprising


Adoption of Conventional Porro Prism Arrangement?

What’s not clear from the available information, is when Zeiss adopted the now usual practice of placing the two Porro Type I prisms in close proximity,
as shown with the 8x30 Deltrintem in post #5 at the start of this thread
Most detailed information about early Zeiss binoculars concerns externally identifiable model variations, rather than the optical aspects

However, the use of relatively widely separated prism pairs continued on at least some established Zeiss designs for a considerable time
e.g. a cut away image of the 6x Telex model (introduced in 1907), which shows significant prism separation, was still in Zeiss catalogues until at least 1928 (see a clear image from a 1923 catalogue)

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And for those interested in historical context:

The maximum separation of prisms was used by Ignazio Porro in the monoculars that he had the firm Hoffman make for him in the 1860’s, see both:
- a cut away image of the Porro Type I model in post #28 at: https://www.birdforum.net/showthread.php?p=3914037#post3914037 , and
- the construction of the much rarer Porro Type II model, at post #70 in the link

In contrast, the images of the binoculars of both Boulanger (c.1859) and Nachet (c.1875), give the impression that the prisms were in close proximity, see post #29 of the link
And the cross-section of Abbe’s 1873 prototype monocular clearly shows the same, at post #30

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Additionally, early competitors to Zeiss such as both Goerz and Steinhall, also made Porro prism binoculars with widely spaced prism pairs
(but in contrast to Zeiss the objectives and eyepieces were vertically orientated, so as to avoid violating the 1893 Abbe patent for the enhanced stereoscopic effect achieved with outboard orientated objectives)



John

Thanks John for the detailed posts.

Regarding post 77.
If there is a loss of 4% per surface then ten surfaces have a loss of 34%.
0.96 to the tenth power is 66.4%

However, some here suggest 5% per surface.
I have always used either 4% or 4.5% as a reasonable loss per surface.
I think it depends on the glass type.
A 4.5% loss per surface gives 63% transmission, a loss of 37%.

In actual fact with other losses even when new the transmission may only have been 55% or less, and now with the deterioration over time, even when cleaned, these original binoculars may be down to 30% transmission.

I think that Gijs has measured very low transmission in some old binoculars.

Here, opera or field glasses of the Dutch or Galilean type may have better transmission but very narrow fields.
But these field glasses got more elements over time, so the gain may not be much over prismatic binoculars.

Regards,
B.

Other Early Porro Prism Designs

A) Relief Fernrohr
In 1894, simultaneous with the introduction of conventional Porro prism binoculars, Zeiss also introduced the distinctive ‘Stereo-telescope’
It was available for civilian purchase, though most use seems to have been by the military. It remained in production until the end of WWI


OPTICAL CONSTRUCTION
Abbe’s patent of 1893 describes and illustrates both the use of:
- a Porro Type II prism variation (lines 61 to 64 on page 3; figures 10 and 11) < see the first image from the patent, and

- a Porro Type I prism variation (lines 119 to 132 on the same page; figures 12, 13 and 14) < see the second image from the patent

(the lines and figures referred to are from the US version of the patent at: https://www.birdforum.net/showpost.php?p=3914041&postcount=30)


However, an image from a 1900 brochure (at: https://issuu.com/zeisshistoricasociety) shows that it was the Porro Type II version that was actually used
i.e. the prism assembly marked ‘Fig.3.’ in the third image from the patent


The optical construction consists of:
- an objective of one triangular prism, followed by a seperate single lens
- a one piece prism of three reflective triangles, and
- an eyepiece of what appears to be a single field lens, followed by a single eye lens


continued . . .

B) 1897 Patent for a Folding Binocular
For completeness I’ve attached a copy of a patent application for a design that was never put into production
see pages 7 and 9 from the article by Larry Gubas at: https://issuu.com/zeisshistoricasociety/docs/pdf-zhs-journal-spring-1990

The design has several interesting aspects, including variable magnification by ‘ . . . shifting an image-reversing lens system’
The mechanism seems to operate in a similar way to that of a variable power telescopic sight i.e. by a sliding optical unit located before the second focal plane
And to have been controlled by the use of a central wheel to adjust the magnification (rather than to focus the binocular)


C) Compact Models
Although both the 1893 Abbe patent, and initial Zeiss production stressed the stereoscopic effect of the wide placement of objectives, Zeiss also explored other possibilities

While most of the early Zeiss binoculars were already compact as they had objectives of 25mm or less, prior to WWI Zeiss also introduced a number of Porro designs
where the objectives were either mounted inboard or over the eyepieces. See the first table at: https://www.birdforum.net/showpost.php?p=3919136&postcount=5

I’ve previously posted some images of the earliest intentionally more compact model at: https://www.birdforum.net/showpost.php?p=3913141&postcount=26
It was a modification of the original 4x design of 1894, so that it could be used either with the objectives:
- in the conventional outboard configuration, or
- above the eyepieces for theatre use

There is some specific information about its use in an 1897 brochure, see the image from: https://issuu.com/zeisshistoricasociety
(the text indicates that this modified version dates from 1897, rather than 1894 as indicated by Leichtfried in the original link)


D) Dual Magnification - Turret Model
Prior to WWI, Zeiss also introduced a dual magnification 5x and 10x model with a 25mm objective
The rationale was that it was a combined day/ night binocular with the higher magnification intended for daytime use, and the lower magnification (and larger exit pupil) for night use
Larry Gubas gives an explanation along with other information at page 7 here: https://issuu.com/zeisshistoricasociety/docs/pdf-zhs-journal-spring-1990

While a rarity, a set of clear images can be found at: http://www.historicacollectibles.co...ine-glas-revolver-5x-10x-ammiraglio-togo-1896, see 2 examples

And remarkably Gijs has tested one for transmission! See the attached page from ‘Multi-functional binoculars and telescopes in the past four centuries’ at:
https://www.houseofoutdoor.com/verrekijkers/verrekijkers-testen-en-vergelijken/


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OPTICAL CONSTRUCTION
In relation to the specific optical construction of either the compact or turret models, I’ve not seen any diagrams or detailed descriptions
However, one would expect that they had a similar construction to that of the other early Porro designs as outlined in post #77


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n.b. in relation to the very low serial numbers on some of the models that I’ve linked to, see Larry Gubas’ comments on page 13 of the article referred to in B) above
i.e. although the particular units are clearly early production (as indicated by their design and details), their numbering seems to be model specific
rather than including all other binoculars since the start of production in 1894


John