How to fix a Canon 50mm f/1.4 Lens with a Stuck Focus Ring

I bought a used Canon 50mm f/1.4 USM Lens off of Craigslist today only to discover once I departed that the focus ring was badly stuck between 3 meters and infinity. I considered taking the lens into a professional service center for repair, but need it for a shoot this weekend and that would take at least two weeks.

I discovered that the focus ring gets stuck often on this model lens and that most people send it off to be serviced. The most common cause seems to be dropping the lens. The method used to fix this isn’t for the faint at heart. I would certainly not recommend this to anyone who has never taken apart anything before (and successfully put it back together again) or someone who has a lot to lose if something were to go wrong.

If you try this and it doesn’t work out, I take NO responsibility for your failings. Do this at your own risk!

Thanks to those who went before me: fatigue from Clubsnap for documenting the entire process of dissassembly and Nick_b of Photography on the Net for documenting the focus ring part correction.

Before you begin, I would recommend getting several dry clean wash clothes to layout the disassembled parts on. You’ll also want a mini-screwdriver set, needle nose pliers and some latex gloves. I got gloves for free from the deli downstairs.

I’m going to try to get permission to republish the steps here. Until then, please follow the links to see directions and discussion.

• Step 1: Disassemble the lens. Personal note: the four screws on the metal mount are very tight and difficult to loosen. I had to apply pressure on the screw with the mini-Philipshead screwdriver and apply torque with the needle nose pliers.
• Step 2: Bend the focus ring back in place. Personal note: I bent mine a little too far and it caused the ring to get stuck at the infinity end. I just used the needle nose pliers to correct the overcompensation. I could see how you could destroy this piece very easily if you weren’t very careful.
• Step 3: Reassemble the lens. Personal note: make sure the four metal mount screws are tight upon completion. I failed to tighten mine all the way. This caused the USM to fail to engage, which meant that the aperture reading in my viewfinder and LCD read 00 and autofocus didn’t work. Tightening the screws fixed the problem.

Results

I just finished a few hours ago and only taken a handful of shots. So far every thing seems in order. I’ll post some pics from this weekends shoot to show how well its working. Here’s a photo taken at night in my bedroom with just the fan lights on. Only time will tell if this has indeed fixed the issue.

The is the full image shrunk down to fit on the web.

This is a close up of the first image to show detail