Full time manual focus on USM lenses

Started Jan 7, 2013 | Questions thread
Matt Senior Member • Posts: 2,387
Re: Full time manual focus on USM lenses

aaa8866 wrote:


I know that USM lenses allow Full time manula focus, so that you can turning the focusing ring in one shot after focus achieved while keeping pressed halway the shutter button.

The question is: if if turn the focus ring WHILE the lens is autofocusing, so while the lens is moving, can I damage the lens?

For example the lens is going from macro mode toward infinite and I turn the ring in the opposite direction, can I damage the lens?

Some say no, because there are no gears with USM lenses... Canon doesn't tell anything about...

Thanks a lot!!!


I dont think it matters, otherwise the feature would be quiet useless and Canon would state that it should not be done.   I would probably not crank the lens one way while its focussing the other way all the time and cant see where this would happen a lot.

For day to day use I would not worry at all.

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