Rusian Normal Lens in Contax Mount

[ernesto]

I have learned in this forum that the Contax mount built in helical, was created for a 5cm normal lens, but I have found that Kiev produced two normals as follows:


Jupiter-8 (5cm/f2), Jupiter-8M (53mm/f2), Helios 103 (53mm/f1.8)


The surprise is that the 50mm or the 53mm comes in the normal mount, which seems to be wrong, from the optical viewpoint.
Anyone have experienced any focus shift using the Jupiter-8M (53mm/f2), or the Helios 103 (53mm/f1.8)?

Ernesto

 

[colyn]

Don't forget the J-3 50mm f/1.5

I have a J-8m and have not had any focus problems with it..

 

[colyn]

The surprise is that the 50mm or the 53mm comes in the normal mount, which seems to be wrong, from the optical viewpoint.
Anyone have experienced any focus shift using the Jupiter-8M (53mm/f2), or the Helios 103 (53mm/f1.8)?

Ernesto

If you compare the mount of the J-8 and J-8m you'll see that one is slightly longer than the other..

 

[ernesto]

Accordingly to these facts:
http://www.rangefinderforum.com/forums/showpost.php?p=840561&postcount=21
There is an incompatibility btween Nikkor normal lens and Contax normal lens, due to a diference in focal length of about one milimeter.
That was the reason for Nikon to redesign the Contax Mount Helical, to make it compatible with their normal focal lenght.

If so, I cannot understand how Kiev offered two normal focal lenght to be mounted in the normal Contax inner mount, which should be designed specifically for one of the option and therefore not for the other.

Since Kiev II is a Contax II they share the same mount and helical, which was created to fit with a 5cm normal lens, therfore how can a 53mm focal lens work properly in that mount?

Ernesto

 

[ernesto]

If you compare the mount of the J-8 and J-8m you'll see that one is slightly longer than the other..

Yes, that is right, and it is possible that both lens could focus properly at infinite, but the phisic of light, tells that the 53mm lens would have serious problems focusing at closer distance and full aperture setting. Have you tried that?
Thanks!

Ernesto

 

[wlewisiii]

IIUC, The Contax/Kiev mount "normal" FL was always 53mm. Earlier lenses simply rounded that off to the expected 50mm (due to that being the FL on Leica) but all were actually 53mm. On later lenses (the Helios 103/Menopta 53/1.8 or the Industar-64L/D 53/2.8) the "full" focal lengthe is listed.

William

 

[ErnestoJL]

The original Tessars and Sonnars designed for the Contax were not "50 mm", in fact FL was slightly different (something like 53 mm or so).
After WWII, Arsenal changed nothing, so any Jupiter is perfectly compatible with Contax bodies, and viceversa.
I have a J12 and a J11 which both fit in the Contax, and take excellent pictures, as well as a CZJ Sonnar f4/135mm which also takes beautifull pictures in the Kiev body.
Sometimes, I exchange J3 (or J8) with the Tessar 50/2.8 in any of the three bodies I have and no problems.

Besides, the nominal FL printed (or engraved) in the front ring of any lens is something close to the real focal lengh it has, and sometimes it is not.
So "50 mm" would be something between 48 to 58 mm... it is something not to be taken as absolute true.

Cheers

Ernesto

 

[40oz]

^ I agree. While I have seen "passports" for FSU lenses that state an actual focal length other than the lens' label, so too have I seen numerous lens reviews of Japanese and German lenses showing the same fact: focal lengths inscribed on the lens are not absolutes.

And I'd put no more creedence to the idea that there is some hidden, secret incompatibility between FSU lenses and German bodies. At least as long as some people have Leica lenses adjusted to mate with specific Leica bodies in order to get "good pictures" and most others do not bother and still manage to take great shots. It seems to me you can either assume some ungodly level of precision is needed to achieve even approximate focus, or decide that focus errors are your own failure and learn to do better with what you have.

 

[tyrone.s]

And I'd put no more creedence to the idea that there is some hidden, secret incompatibility between FSU lenses and German bodies. At least as long as some people have Leica lenses adjusted to mate with specific Leica bodies in order to get "good pictures" and most others do not bother and still manage to take great shots. It seems to me you can either assume some ungodly level of precision is needed to achieve even approximate focus, or decide that focus errors are your own failure and learn to do better with what you have.

Well said! This exactly mirrors my own experiences- FSU lenses mysteriously working correctly on German and Japanese (Voigtlander) bodies.

 

[photovdz]

what you need with all lenses is them to be correctly centered and collimated...
which some of the russian lenses are not (vodka effect on the production) . when corrected ... they are fully compatible...
(only preware FSU lenses are not standardised... )