Several years ago, my Canon EF 50mm f/1.4 lens stopped focusing properly. I threw it into the depths of one of my camera bags, always intending to get it fixed one day. I could have sent it in for service, but I never got around to it. Shortly before the LA wedding shoot two weeks ago, I came across the 50mm while preparing my photographic arsenal. I remember saying to myself that the 50mm was one of Canon’s simplest lenses, and that it couldn’t be that hard to fix. I then proceeded to disassemble the lens in my attempt to fix the sticky focusing ring.
I discovered that the Micro-USM motors were not able to turn correctly when going from 1m to the closest focusing distance of 0.45m. It wasn’t a matter of the screws being too loose. On the contrary, I had to loosen the screws in order for the motors to turn. Additionally, one of the screws on the outside body of the lens was also preventing the lens from functioning correctly. I had to remove that screw too.
After about an hour of work, my 50mm is back to working operation. It was one of the first lenses that I purchased for my EOS D30 back in 2000, and it has created several lovely photos. The focusing ring is certainly not as smooth as it was originally, but I’ll take good enough over broken any day.
I wonder what might have caused the malfunction to happen in the first place? Did the lens get stuck out in the sun and the metals inside expanded too much? Dunno!
I’m writing this post because I just watched a Virtual Lens Plant Flash presentation on Canon’s Camera Museum website. I had seen the link while researching disassembly instructions for the 50mm, but I hadn’t clicked on it until reading out it on RobGalbraith’s site. The presentation is great at showing all the processes and steps to manufacture a Canon lens, in this case a Canon EF 500mm f/4.0L IS. I shall say definitively that the 500mm is much more difficult to manufacture, let alone disassemble, than my 50mm! If I ever have problems with that lens, I’m calling CPS!
tow.com 