Understanding the use of the aperture leaver.

[nhodgkinson]

I have a set of Zeiss Contax lenses that are very good for filming but on my new camera there is a Speed Booster and only the 35-70mm will fit properly. This is because the previous owner filed about 2 mil of the aperture lever and the small protruding piece of metal behind it on the mount.

Now I would like to do this to all my Contax lenses and then I’d have the whole set working on this camera. The tab of metal is part of the legacy Contax mount I believe, so no use to anyone but old film camera enthusiasts but I have never really understood the use of the aperture leaver and would like someone to explain before I shorten it. One of the lenses is the 21mm which has some value these days so I’m a little weary.

 

[dennybeall]

Not sure about that brand but on my old manual Nikon lenses there is a small spring-loaded lever that opens the shutter while you focus and then is released as you take the picture so the shutter can close to whatever f-stop setting for the duration of the shutter activation and then snaps open again.

 

[Derrel]

THE BLACK lever appears to be the actual lever used to stop the lens down and to open the lens up for each exposure; this looks very much like the mechanical diaphragm actuating lever used in the Nikon F-mount lenses. And yes, since the Contax cameras are basically dead-ended, I see no reason to worry about modifying them. I'm not sure about the silver nub behind the black one, but I think that is what indicated the maximum (widest) lens aperture value to the metering system in the Contax or Yashica/Contax cameras....

 

[nhodgkinson]

Thanks as always for your response. The shutter, though I think you mean aperture unless I’ve my terms mixed up, makes sense. To pop the aperture wide open and give the camera enough light to get focus then drop it back down to whatever the aperture ring is set to for the exposure. There are still Contax film cameras that will take advantage of this but I can’t see it being a problem. Shortening these will open the lenses up to many more likely modern mountings, so I think I’ll go ahead. I’ll only shorten it the minimum necessary for it to mount on this Speed Booster in the hope that a few mill will mean it still engages on an older film camera should it ever find it’s self there. I also think you guys are right about the silver nub, some kind of protection for the lever.

 

[dennybeall]

I've always looked at it as the shutter is the mechanical device that sets the aperture opening. As I open the leaves of the shutter the aperture changes.. f32 goes to f16 to f8 to ?? as the leaves of the shutter open.