Canon FDn 50mm 1.4, stiff aperture ring

[zanxion72]

The aperture ring of my Canon FDn 1.4 is too stiff. Looking inside the lens the blades are clean and snappy, but turning the aperture ring requires quite an effort. What makes it so stiff? Can it be remedied, is it easy?

[Gardener]

It's probably just dirt or solidified lube. 30 min repair at worst.

1. Find three screws on the side of the mount. Drop a drop of acetone on each and let it sit a minute.
2. Take out the screws, then pull out the metal mount ring
3. After that everything is trivial - remove parts one by one until you get to the aperture ring, and clean it up with alcohol/paper towels.
4. Apply a bit of grease to the spot where the detent roller is located.
5. Reassemble. This is the most complicated part. The trick is to put it together in active/mounted position. It will likely take you a bit of time and a few tries to get it right.