I think there's no easy way. In the back are usually some two splints held by two screws each (although I cannot recall them from the FD 24 right now).
If you loosen them and hold the lens upside, they usually fall out and you can unscrew the helix and divide the lens body in two parts.
However, in many cases there is a double helix and to reach the inner one can be very difficult since it may be part of the "lens gruop system".
Very important as well is to mark the exact position where the helix divides, so that you find the correct starting point for re-assembly. Otherwise, you may screw it back together in a shifted way, and it will not work properly.
To find a grease which you trust may also be problematic.
I always try to avoid the helix.
Al right, that's clear enough to me : I won't try anything. Like you, I have to unscrew the front element in order to tighten the screws. Because I'll have to visit a Canon repair shop within a few days, maybe I should ask them if they accept to unscrew this.
- Silver Ring work : finally this ring is naturally nested with the aperture ring. Luckily there is not play between this group and the M42 adapter, and the ring remains smooth.
- Infinity tuning : after reading m-a-x's testimony, I tuned the adapter thickness to get infinity without tuning the front screws. This lead me to get intinity and in the same time I measured the minimal focusing distance : 19cm from the front lens.
- Front screws : I made a tiny hole and tried to unscrew the front element. Unfortunately the start of the thread was a little bit damaged in the past, and I was unabled to remove the ring. I'm waiting for a metal hood, I hope this will help in repairing the thread. My polarizer doesn't have a deep enough screw.
It's interesting to see that you used a M42-EOS adapter with a flange at the back. I thought the flange could cause vignetting but it seems to work nicely on the 20D.
Feb 22, 2010 at 06:14 PM
