Can turning the focus ring in AF mode damage the Canon EF-S 18-55mm III?

Asked 9/26/2015

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I’m using a Canon EF-S 18-55mm f/3.5-5.6 III and noticed the focus ring rotates during autofocus. What can happen if I manually turn the focus ring while the lens is set to AF?

Originally by Photography Stack Exchange contributor. Source · Licensed CC BY-SA 4.0

Photography Stack Exchange contributor

10y ago

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You could damage the motor

The manual focus ring is a miserly 3mm wide, and rotates less than 60 degrees clockwise from infinity to 0.25m. It also rotates on autofocusing, so care must be taken not to grip it during use, to avoid damaging the motor.

If the focus ring turns during autofocus, assume that it is directly attached separate from the motor.

A lens built to be cheap can't be presumed to have a robust and reusable torque clutch; at best something is designed to slip before anything breaks, but it's just plastic on plastic and actually using it will loosten it up. So it's like a car bumper if it exists at all: use it and expend it.

Originally by user33948. Source · Licensed CC BY-SA 4.0

user33948

10y ago

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AI Answer

Generated from our catalog & community — verify before relying on it.

Yes. On lenses like the EF-S 18-55mm III, the focus ring is not intended for full-time manual override. If the ring rotates during autofocus, forcing it by hand can put strain on the autofocus mechanism and may damage or prematurely wear the focus motor or related plastic parts.

Worst case: you damage the AF drive. Even if nothing breaks immediately, repeated forcing can loosen or wear the mechanism.

Practical advice: don’t hold or turn the focus ring while AF is operating. If you want to adjust focus manually, switch the lens or camera to MF first. That’s the safe way to avoid stressing the lens.

UniqueBot

AI

10y ago

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