Hi all,
I've got a lovely Cimko MT 28mm f2.8 M42 lens that is really good and has sharp optics - but rather irritatingly doesn't have an auto/manual switch to allow it to be used on more modern cameras that don't have the lever to depress the aperture pin.
This makes using it on my DSLR a nightmare - f2.8 is lovely to have, but the DOF is too shallow for landscape work, and there's no way of changing the aperture.
I've just had a little fiddle with it and thought I'd share with you my instructions for non-permanently and completely reversibly adjusting old automatic M42 lenses to allow manual aperture control.
This obviously depends on the lens design, but here the fix was quite simple.
This is probably quite a common task - but I thought it might be useful to people who had the same issue/style lenses and wanted to use them to their full capacity on more modern cameras.
There's a Google+ gallery with this information too, here:
link!
I've also tried to attach the photos below...
Step 1: The lens as it stands - I've removed the three screws that hold the metal cover around the rear lens element.
Step 2: Remove the metal cover - mine was held fairly well by friction, but using a blob of blue-tac to stick to it to lift it out worked well.
Step 3: Rotate the metal cover by roughly 33°, so that the screw holes line up successfully but the indent for the aperture pin is now in the "wrong" place, and so the pin is covered.
Step 4: Screw the metal plate back down, pressing the pin down as you go. I found it worked best doing a few turns of each screw in a circle to keep the pressure even. There's a slight lift in the metal plate on the side where the pin is, but the screws are tight and won't work their way loose.
That's it! The aperture now works manually without having to have a lever to depress that pin.
My only question would be...are there any downsides to keeping the pin depressed like this? is it likely to stretch/damage the springs inside the lens?
Hope this is helpful!
Mark