Canon 50mm 1.8 FD Breech

freecom2

freecom2

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I purchased a Canon AE-1 on a whim, and it came with an older style Canon 50mm f/1.8 SC (this is an FD mount, with a breech lock). It seems like lots of the Canon 50mm FD lenses have a stuck open aperture, and this one was no exception. I attempted to disassemble the lens, based on the various disassembly guides (although many of these are for the newer Canon 50mm nFD lens) - including removing the focusing helicoid - and unfortunately I can't seem to get it back together. I've worked out that various parts of the focusing helicoid need to slot in to part of the lens mount, but I can't seem to find a way of doing so.

Has anyone done this before, or have any guides for it? The guides for the later Canon 50mm lenses don't seem to cover this, and they are built differently. Alternatively, anyone have a spare Canon 50mm FD lens for sale if I get fed up of doing this? :banana:
 
Well I can't help you dismantling but did you test the lens on the camera as they are all wide open off camera (people who don't know think they are stuck) ....... unless you know the trick on how to check them.
 
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excalibur2 said:
Well I can't help you dismantling but did you test the lens on the camera as they are all wide open off camera (people who don't know think they are stuck) ....... unless you know the trick on how to check them.
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Canon FD lenses are a bit tricky like that (and that can make them great buys). However, most of them tend to sit at f/5.6 (half-way stopped down) when off camera, and this one was sat wide open at f/1.8. When attached to the camera, and using the stop down lever, the aperture didn't change. I checked and the camera stops down other FD lenses fine, so it was definitely the lens.

I managed to get the aperture blades moving again (they were indeed coated in oil, and the back side of the blades were absolutely caked in it), but re-assembly has stumped me.
 
freecom2 said:
Canon FD lenses are a bit tricky like that (and that can make them great buys). However, most of them tend to sit at f/5.6 (half-way stopped down) when off camera, and this one was sat wide open at f/1.8. When attached to the camera, and using the stop down lever, the aperture didn't change. I checked and the camera stops down other FD lenses fine, so it was definitely the lens.

I managed to get the aperture blades moving again (they were indeed coated in oil, and the back side of the blades were absolutely caked in it), but re-assembly has stumped me.
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Indeed off camera the plastic FDn lenses are about f5.6 but the FD breechlock are WO (well mine are).....I know it's great to fix a lens DIY but the 50mm is so cheap it's not worth bothering. I have both FD and FDn and can't see any difference in performance so get which one is the cheapest.
good luck
 
Well checking on camera, and seeing the aperture blades, I'm 99% sure it was indeed a problem. I agree, getting a new one isn't expensive, but definitely want to have given it a proper shot before writing it off.
 
freecom2 said:
Well checking on camera, and seeing the aperture blades, I'm 99% sure it was indeed a problem. I agree, getting a new one isn't expensive, but definitely want to have given it a proper shot before writing it off.
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I've have a Kiron zoom which, is breech lock, also with sticky blades and found it easy to come from the front. Also took apart a Fuji 135mm lens as the focussing was wrong and I too after numerus attempts couldn't get the right helicoid position so put it back and it still has the same problem. :(
 
Decided to buy a Canon AV1 for the 50mm FDn sitting on it... a shame I couldn't get it back together really. Would the parts be useful for anyone?
 
freecom2 said:
Decided to buy a Canon AV1 for the 50mm FDn sitting on it... a shame I couldn't get it back together really. Would the parts be useful for anyone?
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The AV1 is a nice simple camera and Canon produced it just for the Aperture priority fan club. If the elements aren't any good for a magnifying lens, I'd at least keep all the tiny screws as you never know when they might come in handy
 
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