Kiev/Contax lens shim to fit Nikon

[fidget]

I believe that it's possible to match Contax/Kiev lenses to fit the Nikon standard. This would give me a few more (very) cheap lenses to play with. How much change is there in shim thikness?
Dave..

 

[physiognomy]

Dave,

I would go here (click) & ask your question... There is a member on the board who plays with the sort of thing you are asking about.

Good luck!

Peter

 

[Mackinaw]

Ex-Rff'r and noted camera tinkerer, Brian Sweeney, is a contributor on Stephen Gandy's RF list. You may want to sign up and post your question there.

Jim Bielecki

 

[fidget]

After running a few searches, it seems that any reshimming of Kiev lenses is only part of a more fundamental difference in which the focus thread moves over a different range. I take from that, that it doesn't move the lens the same distance between it's limits. Apparently the dof of wide angle lenses can accomodate this, but others, not. Very nearly had a Voigtlander R2s sporting incompatible lenses! Phew!

 

[John Shriver]

Right, the difference is not the infinity focus setting. The difference is that the rotation of the focusing mount is different for a given non-infinity focusing distance on the Contax and Nikon bodies.

You need different pitch threads on the helicals.

 

[Xmas]

The problem is that Nikon made their lenses to the Leitz standard, as they were primarily a lens shop. The success of their bodies forced them to make cameras.
So you can bodge the lens by changing the separation of the elements similar to front cell focusing which wont necessarily improve the performance. But that is real precision lathe work in one direction or shimming in the other.
Noel

 

[VinceC]

Rather than change the lens element spacing (a major optical undertaking) some people adjust the shims on the lens element of 50mm lenses. For example, you can adjust the lens to be at proper focus at a distance of two meters and hope that depth of field helps with other distances. It's a compromise. As stated above, the situation is that the actual screw helical on Contax/Kiev is slightly different than Nikon-S. The lenses focus correctly at infinity but gradually differ as they're focused closer.

 

[Xmas]

Vince

With some of the lens one does not need shims undoing a grub screw rotating the lens and retightening grub will do but as you suggest this is only at one distance, and the effect will be bad with the wide aperature lenses.

Some lens designs are 'resonable insensitive' of element spacing but as well as the mechanical engineering one needs to be an optical design person to pick the best separation arrangement. Lots of lens have floating mounts to minimise abberations, zoom lens rely on the effect.

I did say bodge...

Noel

 

[physiognomy]

Hey Brian,

Glad to have your wealth of knowledge back here on RFF...

Peter