Hello Hello , Sep 06, 2010; 11:51 a.m.
I use a variety of manual lenses and have found that the aperture would stick on some lenses. I turn the ring, but the diaphragm doesn't change, or there is a delay in the change.
The camera fires and the mirror doesn't have any issues clearing the lens. The lenses i used have been given the ok by the usual sources on the web, so i was wondering if anyone else ran across this issue, and whether people could suggest a fix (the lenses i use are primarily leica and contax-zeiss).
Thank you all.
Craig Dickson 
, Sep 06, 2010; 12:44 p.m.
I haven't used Leica or Contax lenses on my 5D2, but I've used Nikkor and Takumar lenses without running into the problem you're describing.
One possibility is that the lens mount adapter you're using is rubbing up against some part of the lens that needs to be able to move freely to change the aperture. My experience has been that the machining on lens mount adapters can be quite inconsistent even between samples of the same model. Given two seemingly identical adapters, often one will work well on lens A but not lens B, while the other has the opposite problem.
Another question is, do these lenses work fine on Leica or Contax cameras? Are you sure there is no mechanical problem with the lenses?
Ilya E 
, Sep 06, 2010; 12:52 p.m.
I don't think it's the adapter. What an adapter has to do with a mechanical aperture ring? Aperture blades do get stuck so it will need to be serviced. I've seen this happen before when I was using manual lenses many years ago.
Juergen Sattleru 
, Sep 06, 2010; 01:27 p.m.
A sticking aperture has nothing to do with your camera - you need to get your lenses serviced.
Paul M (Austin) , Sep 06, 2010; 02:45 p.m.
Look at the aperture blades to see if there is any oil on them. That could cause them to stick. Or, it might be that the auto-aperture lever is not being pushed down far enough by the adapter. In case you don't know what I'm talking about....On mechanical auto-aperture SLR lenses there is a little lever (or pin) on the back of the lens that must be pushed to one side (or depressed) in order for the aperture to stop down when the aperture ring is turned. With a compatible camera body, that lever will get pushed at the time the picture is taken (auto-aperture). When you're using an adapter to use the lens on a camera that isn't designed for that lens, the adapter must keep that lever pushed at all times. If you turn the aperture ring and it only stops down partially (doesn't go any further after a certain point), the adapter could be the problem. Try pushing the lever with your finger and see if it changes.
Hello Hello , Sep 07, 2010; 09:25 a.m.
off the camera (with adapter attached) the len's aperture ring operates as normal...it appears to only occur in one direction...it opens fine, but hangs when stopping down.
i know of the inconsistencies that can occur with adapters, but this one is pretty solid.
i think it has to be something with the camera, but i guess it's no big deal...a little shake before the shot and the diaphragm rights itself.
FYI, i would not recommend fotodiox. i have a pro for my nikon lens which miraculously holds, but both the leica and contax lenses slip off their adapters. I use a novoflex with my leica (expensive but works, the adorama brand holds but wobbles), and two adorama brands for my contax which are firm.
