I spent an hour tackling one of the most challenging camera repairs I’ve dared so far, and it worked! Check out the clean, smooth action on this previously oily, gummed up aperture assembly from a Canon FD 135mm f3.5 breech mount lens!
Since I’ve gotten back into 35mm photography this year, I’ve been itchy to get my hands on a Canon FD 135mm f2.5 breech mount lens like the one my mom gave me in high school. As it turns out, that f2.5 lens is considered to be one of Canon’s best vintage primes, but the aperture on mine became unreliable in high school and I eventually gave it away in the early 2000s. I’ve kept my eye open for a replacement, and I thought I found one in a cheap Canon FTb lot from an auction site. But when I got the package, I discovered the lens was a f3.5, not a f2.5, and it was full of fungus and the aperture wasn’t working. Aaaah!
The first day I got the lens, I opened it up and cleaned the glass. I was able to get rid of the fungus, but it’s still pretty dusty — there are just a lot of flecks in there I can’t quite get out. I strongly suspect they won’t affect image quality, but I wasn’t ready to test the lens yet because the aperture was stuck wide open.
This morning I had a spare hour, so I finally opened up the lens again, removed and opened up the aperture assembly, and carefully used isopropyl alcohol to clean the housing and blades, which were indeed oily and sticky. Huge thanks to mikeno2, whose video about cleaning this model of lens was incredibly helpful.
The toughest part of the job was reassembling the aperture assembly. Tiny pegs on the bases of the blades fit into tiny holes in two different parts of the housing, and the blades overlap in a circular pattern, and the very last blade has to tuck under the very first blade, which is a tricky maneuver. But it all worked out, and now I have what looks like a working Canon FD 135mm f3.5 breech mount lens!
This is a lot of effort for a lens that can be bought in good condition for under $40. But it’s enormously gratifying to fix up something that came to me in such bad condition.
Yes, I’ve still got my eye open for the f2.5 version of this lens, but for now, I’m going to have a lot of fun testing out my repaired f3.5 in the field.