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Alan_m
Tinkerer
Username: Alan_m
Post Number: 1
Registered: 09-2012
Rating: N/A
Votes: 0 (Vote!) | | Posted on Friday, September 28, 2012 - 11:38 am: | 
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Hi all, I sucessfully opened up my Canon fd 35/2 chrome nose (1971 original, pre-SSC) to clean some hazy elements, with the help of some Canon diagrams i found on flickr:
http://www.flickr.com/photos/23174454@N00/6979325955/
Then the focusing ring loosened so I opened it up again, but ran into a problem this time! The aperture ring came off, and with it two loose ball-bearings fell out (that detent/click the apertures), and a mysterious 3rd bearing that I can't figure out where it came from. I can get the other two back into their holes on the side, but the aperture ring doesn't quite fit back on snugly or straight and seems to be sitting awkwardly on a spring that runs around. I wonder if the third bearing goes underneath it somehow, or somewhere else completely? I can't see a reference to it on the diagrams, and it's certainly not obvious. Maybe it came out of the mount?
Anyone have any experience of disassembling this part of the mechanism? Amazing that there isn't anything I can find on the web.
Thanks! |
Cooltouch
Tinkerer
Username: Cooltouch
Post Number: 224
Registered: 01-2009
Rating: N/A
Votes: 0 (Vote!) | | Posted on Friday, September 28, 2012 - 06:12 pm: |
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That Flickr illustration is next to useless. No enlargements are possible and I can't tell what any of the small detail is supposed to be. You might try writing to the guy, see if he's willing to put up a larger size file.
Or you can pays your money.  This eBay seller appears to have exactly the repair guide you're looking for:
http://www.ebay.com/itm/Canon-FD-Lens-Repair-Manual-Early-Breech-Lock-Models-/22 0925119075?pt=LH_DefaultDomain_0&hash=item337029ca63
It's for the early FD breechlock lenses, like your chrome nose 35.
I've been in similar situations before, trying to figure out where a tiny ball bearing was supposed to go. What I figured out was to look for signs of wear that the ball bearing would have left behind. Chances are there will be faint wipe marks somewhere on the metal that it was moving across that might give away its original location.
I have seen some lens mounts that use ball bearings in their linkage races, but I can't remembers specifically which ones, or even if they were Canon mount. But it's a factor to eliminate perhaps. |
Glenn
Tinkerer
Username: Glenn
Post Number: 1046
Registered: 07-2006
Rating: N/A
Votes: 0 (Vote!) | | Posted on Sunday, September 30, 2012 - 10:29 am: |
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These reprints of the official Canon manuals are a must for anybody seriously into Canon lens repair. Note what the advertiser states - these manuals do not contain vast amounts of written instructions - the reason for this is that all official Canon repair techs had to attend hands on repair sessions run by a factory foreman/manager. Thus the manuals contain vast amounts of diagrams and pictures to act as an aide memoire once one was back at base and working in the real world.
for Cooltouch's information; in the Canon nFD series of lenses there are two types of rear mount assemblies - for ease these are named as the nFD 50mm/f1.8 type and the 50mm/f1.4 type. The f1.8 type is a cheap cost cutting solution to transferring aperture selection and information between lens and camera body. Friction within the mechanism means that aperture operation on fast wide angles and telephoto lenses is compromised at fast shutter speeds. The f1.4 mount assembly is a very sophisticated solution - strip it down at your peril as it contains a vast amount of 1mm ball bearings (104 if memory holds). It is no good trying to hold the balls on the race with a smearing of grease either as you try and reassemble, the assembly runs dry. This is why when you rotate a lens with this type of mount back and forth around the optical axis, one hears the balls shifting around between the two races. No noise means either the balls are 'gummed' up, or some cowboy has opened up the lens and dropped the balls all over the kitchen floor! |
Cooltouch
Tinkerer
Username: Cooltouch
Post Number: 228
Registered: 01-2009
Rating: N/A
Votes: 0 (Vote!) | | Posted on Sunday, September 30, 2012 - 11:41 pm: |
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Hey Glenn, thanks for the memory jog. Sounds like the nFD's use of many ball bearings isn't applicable to Alan's problem, though, since his is an early chrome nose.
I've removed the mounts from various nFD lenses in the past. Guess I was lucky that none of them were of the 50/1.4 variety. Or if they were, I've successfully blocked the traumatic memory from my mind. ;) |
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