Can I damage the focus system by turning the focus ring when the lens isn't mounted?

Question

I have a couple lenses that don't have an internal focusing system, and whenever I want to put them back in my bag, I turn the focus ring to make the lens shorter.

I noticed that when the lens is set to auto focus, the focus ring is harder to move than when it is on manual focus. Can I damage the focusing system by turning the focus ring when the lens is set to auto focus?

I would think that if the lens is off the camera it wouldn't cause any damage. Am I right?

Answer

I think that depends a bit on the construction of the AF mechanism in the lens. If there is resistance when turning the focus ring, this also means that there is greater force applied to move the mechanics, and so there is greater stress in the material. I would personally switch over to manual focus for that procedure.

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