Opening the back of Contax C/Y Zeiss lenses

propellor · Joined: 29 Apr 2010 Posts: 205 Location: Amsterdam

I have a couple of Contax C/Y Zeiss lenses that I want to use on my 5D MkII for filming. Adapters are no problem but I want to "de-click" the apertures for more precise control.

I have found a couple of posts here and in other places about how to open up the lens. The pictures I have seen of the back of these lenses are different from mine.
All the pics show that the ring that holds the aperture ring is fastened with 4 screws. My lenses, 28/2.8, #6135606, 50/1.4, # 6048695 and 135/2.8, # 6136501, do NOT have these screws ????
I tried to open by removing the lip on the rear lens barrel surround and unscrewing the 3 screws in the mount. After that nothing comes loose though. I am unable to get the mount and the back of the lens of.

Does anyone have an idea on how to do this?

Thanx,
Bart.

calvin83 · Joined: 12 Apr 2009 Posts: 7553 Location: Hong Kong

The structure of the lens mount in C/Y lens varies from lens to lens. Post some photos of your own.

martyn_bannister · Joined: 23 May 2010 Posts: 1151

Without photos it is difficult, but is it possible there is a mounting ring at the rear which unscrews?

propellor · Joined: 29 Apr 2010 Posts: 205 Location: Amsterdam

Here are some pics of the rear.

I removed the small curved block and removed the 3 screws to get the ring of.

Underneath are 4 silver colored screws. I can get these out no problem but then nothing moves. It looks like I should be able to get the mount of, but unfortunately nothing moves.

Any ideas out there?

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a20010494 · Joined: 15 Feb 2010 Posts: 396 Location: Per�.

I was in the same position as you. AEJ? Anyway, those screws are for the helicoid. AFAIK, there's no way to remove the mount, unless its a MM lens.

koji · Expire: 2012-12-27

I think it is pretty easy to do, just remove a ball bearing which makes
"a click" for the aperture ring. But if you are not sure how, visit LEITAX.

http://www.leitax.com/

and just go CONTAX to NIKON page, there are bunch of examples
how to install the new mount. In these photos, you can find a photo
how to find "a ball bearing" I hope.

propellor · Joined: 29 Apr 2010 Posts: 205 Location: Amsterdam

Unfortunately the Leitax page only shows the mounts WITH screws. Mine doesn't have the screws. It looks to be a difficult thing to get inside.

Removing the ball bearing is a piece of cake. I already did that to a couple of zebra Flek's and a Pancolar.

Anyone else have an idea or manual or experience?