135L focus ring sticking, any suggestions?

[Axilrod]

My 135mm f/2 is getting stuck while focusing, i mean the ring keeps spinning, but you can see the distance marks stopping. It doesn't happen every time, just here and there. Any ideas as to what may be causing this?

 

[distant.star]

Easy. Disassemble the lense. Put everything in the dishwasher and give it a good wash and dry. Put it back together and all will be fine.

Seriously, that doesn't sound good. First thing anyone who knows anything will need to find out -- is this in AF or MF or both? Seems like if it's only AF it may be electronic. If it also happens in MF, could more likely be mechanical. Either way, sounds like money may need to be spent.

 

[distant.star]

After thinking about this a little, I'd suggest two things.

First, try some troubleshooting. Turn off AF and see if it ever happens in MF.

Second, try cleaning the electrical contacts between camera and lens and see if it still happens using AF.

Oh, and under all circumstances, use a fully charged battery.

Just some things I'd try.

 

[Mt Spokane Photography]

There is a slip clutch in the Ring USM system that will let the focus ring turn and override AF. If the AF is jammed, its likely in need of repair.

Does it focus when you switch to MF?

In any event, get it repaired, it might get worse, and won't heal itself.

 

[MazV-L]

Sounds similar to a problem I had with my 100mm 2.8L focus, my lens focus ring would slip on AF or MF flicking the focus -range switch made no difference, it just seemed stuck, I sent it off to Canon, they replaced the Front Ring and I've not had any further trouble with it

 

[Axilrod]

After thinking about this a little, I'd suggest two things.

First, try some troubleshooting. Turn off AF and see if it ever happens in MF.

Second, try cleaning the electrical contacts between camera and lens and see if it still happens using AF.

Oh, and under all circumstances, use a fully charged battery.

Just some things I'd try.

AF works absolutely fine and it doesn't seem to get hung up , but I shoot MF 99% of the time. I can rack from infinity and back 10 times in a row and it may not get caught up at all. And when I say it gets "caught up," its never just gotten completely stuck in one spot. It just will stick for a second while turning the focus ring, usually around the 4/5 foot focus mark. Does that make sense?

Thanks for your suggestions guys