I recently picked up a used Nikon 80-200 f/2.8 D lens off Ebay to serve as a portrait and telephoto lens in my arsenal. I got a really good deal on it and ended up with a model that has flawless glass and a super clean body.

But.

The lens had one flaw that while not a deal-breaker was annoying. The AF mode lock ring would not stay locked in either the manual or auto-focus position. It’s not a huge deal, but it’s easy to bump the ring while using the lens and change focus modes. Since this is an older screw-type focus lens autofocus won’t work at all if the lens isn’t in the A mode, so accidentally bumping it could cause me to miss a shot.

This problem is well-documented online, and repairs can range in the $150-$300 range depending on where you go. The issue is that apparently this is likely to happen again through normal use. This seems to be a flaw with almost all Nikon lenses that use this type of lock ring.

Fortunately I found a really cheap and easy solution to this that doesn’t require sending the lens out for repairs! The specific issue with mine is that the spring that pushes up the lock button seemed to have given out, which caused the lens to never be able to lock into place. My solution here was to buy some cheap o-rings and slip it under the button to replace the spring.

I used 4mm OD, 2mm ID o-rings I found on Amazon. The button itself is roughly 4mm wide so these are almost a perfect fit. It’s difficult to get the o-rings on the button. I used a bobby pin to hold the button up and slip the o-ring over the top.

This totally solved my problem. The button is a little harder to press now than it should be, but the ring doesn’t slip anymore and it only cost me $5!

I look forward to shooting around with this monster of a lens.