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How do I remove the rear lens cap from a Canon manual focus FD lens.? Answered

 This is a 50mm lens from a Canon manual focus A1 camera.  The knurled metal ring on the rear of the lens will not turn. I could have installed a cap from one of the newer style FD lenses.


It's possible that someone tried to force the cap on and, essentially, cross-threaded the cap.. All I can suggest is gentle wiggling of cap and ring until it releases. Pressing in on the cap might also help.

There's an interlock pin which is supposed to keep the ring from turning from the unlocked position unless the lens is attached to a camera or cap. If someone tried to shove the cap on and rotate it into place, rather than aligning it properly and rotating the ring, that pin may not be depressed and the ring may not be able to rotate -- or, alternatively, the ring may already be in the unlocked position and all you can do is try to rotate the cap back the other way and hope not to damage anything.

If you can't figure out what's going on, take it to a camera store that's been around long enough to have sold FD lenses. They may still have someone on staff who remembers them and who has seen this problem before.

Sorry, but that's the best I can do without having the beast in my hands.

Thank you for your kind advise.  I'm working with the beast now.


If they can't help you google "camera repair".  There is another forum that I can't remember the name of that has a lot of really smart people who repair and rebuild cameras.

Remember (If you're still working on this...) That the release button on the lens has to be depressed while you are trying to turn the rear cap. I did work in a camera store in the 80's and know a lot of people that were familiar with Nikon lenses and and Pentax screw mounts forget that. The Canon FD rear lens cap is built exactly the same way as the mount on the camera.

Go to these forums.  They are basically run by Canon users.  I remember back a while ago there were several question of the same type.  Some of the lenses have pins or levers that must be protected when you force the lens cap off.  If it 's the wrong type a pin is jamming the release mech.

If you force it you may ruin the lens.

Good luck.

Thank you for your kind advise.  I've joined the Canon Forum.