28mm M-Rokkor flange replacement

[Coloribus]

I am trying to restore a 28mm M-rokkor with clean glass, which unfortunately is missing the rear flange. I was looking for used damaged rokkors to use as donor units, but even the ugliest ones go for more than £150. I was wondering if anyone knows whether the rokkor 90mm flange would work. I would also appreciate if anyone had information on who might have such parts available. Many thanks.

 

[a.noctilux]

Hello,
M-Rokkor 90mm when mounted on a CLE index 90mm framelines.
While M-Rokkor 28mm only 28mm framelines.
If you swap the flange, the 28 would show 90mm in finder with 28mm which is always visible.
Why not if you can live with that.

A better idea is finding a flange for 35mm in M mount if the screw holes fit.
Plenty of M flanges is selling for people who want to 6bit code lenses for digital M.
This link may help:
https://dclindesign.wordpress.com/2011/11/23/6-bit-your-old-lens/

Arnaud

 

[Coloribus]

Hello,
M-Rokkor 90mm when mounted on a CLE index 90mm framelines.
While M-Rokkor 28mm only 28mm framelines.
If you swap the flange, the 28 would show 90mm in finder with 28mm which is always visible.
Why not if you can live with that.

A better idea is finding a flange for 35mm in M mount if the screw holes fit.
Plenty of M flanges is selling for people who want to 6bit code lenses for digital M.
This link may help:
https://dclindesign.wordpress.com/2011/11/23/6-bit-your-old-lens/

Arnaud

Thanks Arnaud. I am waiting for my CLE to arrive so I don't know whether the 28mm frame and 90mm come up together. Unfortunately the screw pattern for the m-rokkors seem to be different to the leica, hence those flange wouldn't work.

 

[f16sunshine]

I don't know about the 28mm build technique.

On the 40mm M rokkor, the flange and the helicoid thread are one unit.
Is it clear that the two halves of the helicoid are in the lens?
If it's built like the 40mm is, only another 28mm flange will be a suitable donor.

Best!

 

[Coloribus]

I don't know about the 28mm build technique.

On the 40mm M rokkor, the flange and the helicoid thread are one unit.
Is it clear that the two halves of the helicoid are in the lens?
If it's built like the 40mm is, only another 28mm flange will be a suitable donor.

Best!

Thanks. I guess I need to find a 28mm to cannibalise for its flange.

 

[David Hughes]

Hi,

How about one of the Chinese 28mm screw to M adapters and a minor bit of engineering? Only a suggestion as I don't know what the back of the 28mm for the CLE looks like...

Regards, David

 

[Coloribus]

Hi,

How about one of the Chinese 28mm screw to M adapters and a minor bit of engineering? Only a suggestion as I don't know what the back of the 28mm for the CLE looks like...

Regards, David

When I get some time I'll take some pictures. Hopefully someone will find it useful in the future. But if the flange is part of the helicoid (I can't see why from engineering point of view) then I'm afraid the easiest way is to take it off another 28mm.