I am not the only one to have noticed considerable similarities between one rather prominent lens (the Vario-Prakticar 35–70/2.7–3.5, the first Carl Zeiss Jena Zoom) and a rather run-of the mill Japanese Zoom lens (the Chinon 35–70/2.7–3.5). Not only do they share identical mainline specifications, these specifications (especially the maximum aperture) are rather rare. When one digs deeper it becomes obvious that these lenses share another conspicuous trait in that both are two-ring zooms that have the same filter thread diameter and both offer a macro mode beyond 70 mm, that you engage by pressing a button on the zoom ring!
That’s it! They have to be the same lens! Right?!
Well that at least is the conclusion some have drawn1 and in these speculations the deepening collaboration between the Japanese and East German optical industries in the 1980s always plays a role.
Interestingly, some take this to mean that Carl Zeiss Jena – as thanks to their Japanese collaborators – gave the designs for the brand-spanking new 35-70 Vario-Pancolar/Prakticar to the Japanese. In this narrative the Chinon 35–70/2.7–3.5 is a Japanese rebrand of the East German marvel and – as it can be had for around 20 euros/dollars – a damn fine deal.
Others seem to think that the intellectual property was streaming the other way. They point at the fact that several Japanese and Korean lenses were sold as Carl Zeiss Jena and Pentacon lenses, and see this just as a Japanese-designed lens made in East Germany. In this narrative the Vario-Pancolar/Prakticar is the “a second-rate Japanese design manufactured to dismal East German standards”.
I think that those who offer these speculations have either never been able to compare these lenses side-by-side or have lacked the expertise to look beyond superficialities, because while I admit that even I was tickled by the obvious commonalities (see above), on close inspection I have a hard time believing these lenses are related.
Why the Chinon and Carl Zeiss Jena 35–70/2.7–3.5 are not closely related
The similarities and differences are easiest to visualise through a small table:
| Characteristic | Carl Zeiss Jena | Chinon |
|---|---|---|
| Length | 75,2 mm | 85,1 mm |
| Diameter | 64,3 mm | 65,3 mm |
| Filter thread | 58 mm | 58 mm |
| Weight | 381 grams | 442 grams |
| Elements & Groups | 9 elements, 8 groups | 7 elements, 7 groups |
| Aperture blades | 6 star-shaped | 8 straight |
| Minimum focus distance (measured) | 83 cm@35mm; 81 cm@70mm; 27 cm@macro | 78 cm@35mm; 67 cm@70mm; 25 cm@macro |
| Macro mode | Yes, at 70 mm | Yes, at 70 mm |
| Max. Magnification @ 35mm; @70mm; (in macro mode) | 1:22,2 (@35mm); 1:11,0 (@70mm); 1:2,9 (macro) | 1:20,4 (@35mm); 1:9,7 (@70mm); 1:2,4 (macro) |
| Lens is shortest/longest at | ≈ 63/35 mm | 70/35 mm |
| Zoom extension | 11,7 mm | 23,9 mm |
| Focus extension | 4,7 mm | 8,3 mm |
| Macro extension | 13,8 mm | 23,8 mm |
| Rearmost element movement while zooming | does not move | moves toward film plane when zooming 70->35 mm |
Besides that there are several easily visible differences, the most striking difference is in the bulkiness of the two lenses – a difference that really sunk in for me only once I compared the two lenses side by side. For you to be able to share the epiphany, I made a scale-true comparison for your benefit.
In sum, it is clearly evident that these two lenses are not one and the same. Moreover there are a number of differences that go beyond a mere “minor tweak”. This is most evident in terms of the different movement ranges and optical design (number of elements and groups) of the lenses. Moreover, if you read the detailed article of the development of the Carl Zeiss Jena Vario-Prakticar over at zeissikonveb.de, you can see that their design really was based on using a broad repertoire of optical glasses2 to tweak the design.
However, it is also clear that these two lenses share a fundamental design principle wherein the lens is divided up into three groups of elements:
• a group at the front that handles focusing and
• two groups in the rear that
• can move apart to facilitate zooming, or
• can move together to facilitate the macro-mode.
In the case of the CZJ lens a further static layer of BK7 glass is added as a last element, resulting in a design that looks like the image above.
So they’re not the same. But which one is better?
They are both very capable legacy zooms, but if you’re into pixel peeping the CZJ wins comfortably, especially because it is sharper wide open. Personally I also like its warmer tones and think its bokeh has a more calm general tendency, but you can be the judge of that.
