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Cooltouch
Tinkerer
Username: Cooltouch
Post Number: 212
Registered: 01-2009
Rating: N/A
Votes: 0 (Vote!) | | Posted on Friday, September 07, 2012 - 10:16 am: | 
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This lens is the big, pro model 35-70 that Canon produced as both a breechlock and New FD model back in the 70s and 80s. Mine is New FD, and I suspect it is the mount that is giving me a problem. It will almost achieve infinity focus, but lacks enough for there to be no doubt, especially at 70mm. The back of the lens is somewhat loose. There are three tiny screws that I thought were responsible for holding the rear assembly onto the back of the lens. I tightened them and that did help -- some. But I've since noticed that it is possible still to move the rear assembly back and forth even with the screws screwed down tight.
I've had to tear into the rears of New FD lenses before, and it's a chore that I don't particularly look forward to. So I'm wondering if somebody here might could provide me with the lowdown on how I can get into the lens far enough to tighten things down or adjust it without having to do any more dismantling than I need to.
There is a collar at the base of the lens which contains the lens mount/dismount button. It's held in place by three Phillips screws. There's also a thin collar that surrounds the base of the lens which contains the aperture coupling mechanisms. This collar appears to be held in place by three smaller Phillips screws. I'm wondering first of all if both collars will need to come off, and if not, which one does? Further, once I've gotten past the exterior pieces of the mount, what next? Where should I look to tighten things up or adjust to set things back right?
The lens shows some evidence of the three tiny squib screws being loosened before but everything else looks to be undisturbed. So I kinda doubt that it was disassembled and then reassembled with the lens helical being one thread off. I've been there done that before, and I know what that's like. This condition is not nearly as severe. Any help you can provide will be greatly appreciated. |
Cooltouch
Tinkerer
Username: Cooltouch
Post Number: 213
Registered: 01-2009
Rating: N/A
Votes: 0 (Vote!) | | Posted on Friday, September 07, 2012 - 01:12 pm: |
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Yay! I managed to solve my own problem. For a change, I did something right, and didn't have to undo any more pieces of the lens than I needed to. Well, almost. I removed the three tiny squib screws, which in retrospect, I now realize I didn't have to remove, but which allowed a sleeve to drop down, revealing four countersunk Phillips screws that hold the base assembly in place. These four screws were loose. So I pushed in on the base assembly toward the front of the lens, and tightened the four screws. Mounted it onto an A-1, and zip, zing, zammo! Infinity focus has returned. That was pretty easy actually.
Now comes the fun part. I gotta try and get those squib screws back into their holes. |
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