Canon new FD (FDn) focus slop.

Greg_E · Joined: 19 Dec 2013 Posts: 18

So I have a Canon FDn 24f2.8 and 35f2 new FD that have some slop between the focus ring and the helicoid. I took the front of the 35 apart last night, but can't figure out how to get the focus ring off. The ring has a brass "roller" that rides in a fork, the fork is screwed to the helicoid and allows you to adjust the infinity. I pulled a bunch of little pieces of plastic out of this area, obviously that roller had a plastic surrounding it and taking up the space in the fork (preventing the slop). I need to unscrew that roller so I can make a new plastic surround, or make a complete roller. The roller is screwed in from the inside of the focus ring, no way to pull it from the outside. And yes I did pull the rubber off the ring, no screws there, a few holes but I didn't find any screws that they might be used with.

I also have a 15f2.8, 50f1.2, and 85f1.8 in this series, pretty sure they are assembled the same, and that all of them will need this repair in the near future.

Sorry, it was late so I didn't take any pictures last night, can do this next time I sit down to work on them.

Gardener · Joined: 22 Sep 2013 Posts: 950 Location: USA

The outer helicoid is supposed to have holes through which you should be able to access the screws.

Greg_E · Joined: 19 Dec 2013 Posts: 18

I thought that's what they were for, but didn't see anything. I'll take a closer look next time I work on it. Thinking I might be able to make a plastic "liner" for the fork, then I could make a repair that would not need the rubber on the focus ring to be removed. This is actually kind of important because I'm putting gears on them to use for video, have to cut the gears off to get the rubber off (right now the 24 only, but you see where I'm going).

Gardener · Joined: 22 Sep 2013 Posts: 950 Location: USA

Nah, you need to peel the rubber off (major PITA!) pop the innards out and replace the roller bushings. I have a 24 on my bench and I keep trying every roller I get my hands on, but so far I have not been able to find and adequate replacement. So my general advice is - unless you have grinding/obstruction from chunks of decomposed liner - just live with the play.

Greg_E · Joined: 19 Dec 2013 Posts: 18

Sort of got it apart, every roller in there was trashed. Guess I'll try to cut new ones out of delrin and see what happens. Most of the optics had oil all over them, really poor shape for a lens described as excellent+++. Guess they use a different rating system in Japan.

cooltouch · Joined: 15 Jan 2009 Posts: 9109 Location: Houston, Texas

Touch wood over here. I've been shooting with nFD lenses for over 30 years and have never had this sort of problems with them. I have had it with a couple others -- both Vivitar Series 1 lenses, in fact. The teflon or plastic or whatever the roller bushings were made out of had just been trashed, resulting in a lot of zoom slop. When I tore into them to find out what the problem was, I quickly realized there wasn't much I could do about them. And then I discovered that the screws that hold these bushings in place -- some of their screw holes in the barrel were stripped out. Once I discovered this, I realized the lenses had become interesting looking piles of junk. I've often heard complaints about how the nFD lenses aren't built as ruggedly as the older breechlock versions, but I have yet to experience these problems. However, I do tend to baby my gear, and maybe that has helped some.

I hope you can get yours back in operation, though, and if you come across a suitable substitute for the bushings, let us know.

Greg_E · Joined: 19 Dec 2013 Posts: 18

Bull by horns as it were:

What I pulled out:

And what I started making:

Would be faster if I had a lathe, but for now I will continue to use my milling machine. Using white Delrin because it was easy to get and cheap, I have enough to do about 15 lenses. Not sure if it is going to work, need to get them all cut down and cut to length before I can attempt to put the lens back together and fight with the double helicoid to get it aligned properly. Never did manage to get the focus ring off, think you need to go in through the back side to get the screws.