topic Re: Manual Focus problem in EF & RF Lenses

Manual Focus problem

Busby — Thu, 03 Mar 2016 10:28:54 GMT

My Canon 16-35mm f2.8 lens is working fine in auto focus but when i switch to manual focus the focusing ring won't turn

Re: Manual Focus problem

kvbarkley — Thu, 03 Mar 2016 16:08:40 GMT

Sounds like something is not dis-engaging when it should.

You can either send it to Canon or try a tear down to see if anything obvious is there.

LensRentals only have one for the f/4:

https://www.lensrentals.com/blog/2014/07/of-course-we-took-one-apart

Re: Manual Focus problem

ezpop — Thu, 03 Mar 2016 23:51:54 GMT

Your lens may have been dropped. Since AF is okay, one possible cause of the manual focus not working is the off position of the silver face cam (retaining ring) i.e. the top ring of the USM assembly. It may be as easy as a slight twist to tighten it up and to bring the manual focus back to life. Or you may have to do several adjustments to balance the right tension for both MF/AF. There may be other causes as well.

Another post here in this forum discribed how I repaired a L lens with the similar USM unit.

http://community.usa.canon.com/t5/Lenses/Canon-EF-24-70-F2-8-manual-focus-slip/m-p/165429#U165429

Do not attempt to open up the lens to repair unless you have some experience doing so or you won't mind sending it to Canon for repair and pay something like $300 or so to make it right. Flex cables are easily broken and it is not easy to dismantle and put things back properly. DIY repair is at your own risk.

Good luck.