Rokkor parts for a summicron

[Cagliostro73]

Hi!
I've compulsively bought :bang: a rokkor 40c chassis (no lens, only metal parts, no screws) to replace the old one i own with the rubber hood stuck (see my other thread). It's completely new.
Do you think the parts will be interchangeable?
How to proceed with the transplant?
Suggestions?
Thank you.
D.

 

[ferider]

You can probably swap the focusing mount entirely, but you will need to re-shim the optical barrel.

Best is to take off the span ring in the back and try.

Then again, not sure how this will help with the stuck hood.

Roland.

 

[Palaeoboy]

Sorry I dont quite understand what you want to do could you explain a little further? You want to put the optics from a Summicron C into the barrel of the first type of Rokkor, is that correct?

 

[Cagliostro73]

Palaeoboy yes it is correct but i've noticed it is not a "first type" rokkor ('cause it has not the serial number on the fron part).
I think i cannot use it unless in an emergency...

 

[Ronald M]

The actual focal length is probably not exactly 40 mm. Different focus mounts or shims are needed to get exact focus to account for the discrepancy in manufacturing tolerences.

So the answer is it may or may not work. It may require pro help, or may not be compatable.

 

[Palaeoboy]

If the barrel is the 2nd type Rokkor I cant see an easy optics swap. The 2nd type uses a conventional M cam system. The first type uses the CL steep cam. Even if the barrel is the first type Rokkor the optics would be swappable as the barrel is near identical to the Summicron (Parts are shared between the two even though assembled in different countries) however a important part of the C type lens manufacture was that the cams were hand ground matched to the optics, a quality feature for such a bargain priced lens. Changing optics from one C lens to the other may result in a quality loss due to a mismatched cam. Im not sure the whole procedure is worth it in the end.

 

[Cagliostro73]

Thank you so much for your precious replies!
IMO this forum is really a treasure.