How do I remove the rear lens cap from a Canon lens?

Question

Someone has donated a 135mm f2.8 Vivitar short telephoto lens to a charity shop that I have been helping at. The lens has a canon rear lens cap fitted so I assume it is a canon mount.

I tried to remove the cap to check the rear elements for fungus etc but it does not budge. I have tried a reasonable degree of force both anti clockwise and clockwise. I have also tried pushing and pulling for a bayonet type fitting. There are no obvious lugs or buttons and the lens mount looks like it has three bayonet slots that engage with a clockwise movement.

Can anyone help? I don't want to damage the lens and my reputation as the shops photographic equipment specialist is at stake.

Thanks.

Answer 1

You have to unlock the cameras ring that's behind the aperture ring. That was a problem with the early Canon lens. You may have to turn it to the right then turn the lens to the left to remove it.

Answer 2

You most likely have an older Canon FD mount lens (discontinued and replaced by the current EF series).  To remove the rear lenscam, rotate the chrome ring at the base of the lens.  When it rotates, it will unlock the cap.  To replace the rear cap or to mount the lens on an older Canon camera, twist the chrome ring in the opposite direction.

Answer 3

Sounds to me like this might not be the case and someone has pushed the lens cap on causing it to Seize.

As the lens cap is plastic and the mount will be steel, I would imagine that a bit of brute force would damage the cap but not the lens.  I can't see any other way to do it without destroying the cap.  Having said that, I know it's not ideal trying to sell a lens without a cap but any purchaser would surely have it cleaned before use, in case any foreign bodies have gone inside.

Answer 4

canon lens caps (rear) unscrew anti clockwise and should take almost no force. it sounds like it is well attached. You should try putting a small amount of oil around the edges.