Contax Carl Zeiss Lenses on Canon 5D

I want to use Carl Zeiss lenses on my 5D - I got a 50/1.4 MM but notice

that the diaphragm does not close down when I change the f-stop. It stays

at f1.4, no matter what setting. Is this because it is MM type? Or is this

lens defect? Is there a way to convert MM to AE so that the diaphragm

closes when I set the f-stop?

Appreciate any advise.... Thanks!

Both MM and AE should allow you to stop down the iris without mounting the lens (like a Nikkor). You may have a case of oil on blade, problem.

Zeiss Contax/Yashica mount lenses do not stop down unless they are mounted to a body, or you hit the trigger on the lens mount. Remember that all Contax/Yashica SLRs meter at full aperture, so changing the aperture ring's setting will not close down the lens unless the little tab on the mount is triggered, which only happens when the DOF preview button or when the shutter is pressed.

Aaron Meyer:

"Zeiss Contax/Yashica mount lenses do not stop down unless they are mounted to a body"

 

Sorry, but that's wrong, at least in the AE lenses. I have 1 Zeiss, 4 Yashicas and 2 C/Y Sigmas, all of them stop down if I turn the aperture ring when unmounted. It is the other way: a tab keeps them fully open when mounted unless you fire the shutter or press the DOF preview button.

<<Aaron Meyer: "Zeiss Contax/Yashica mount lenses do not stop down unless they are mounted to a body"

 

Sorry, but that's wrong, at least in the AE lenses. I have 1 Zeiss, 4 Yashicas and 2 C/Y Sigmas, all of them stop down if I turn the aperture ring when unmounted. It is the other way: a tab keeps them fully open when mounted unless you fire the shutter or press the DOF preview button.>>

 

That's what I get for replying early in the morning. :-) You're absolutely right, of course, and I had it arse-backwards.

MM is like that too. I have both (AE and MM) and they both stop down without mounting.

You might tried this already (please excuse me if you did or know that), but usually there is a switch on Zeiss lenses allowing you to focus either with the lens wide open and close the diaphragm only during shooting (automatic mode, usually marked by the letter A) or to open and close the diaphragm continuously (manual mode, usually marked by the letter M).

 

What you are describing sounds like the behaviour of a lens switched into A mode. Hope this helps.