Lens damage

[duncan22]

Most lenses have a MF or AF setting and on the more expensive lens I understand it is possible to manually adjust the focus even with the lens set to AF.
What is the position regarding cheaper lenses if you do this as it's a very easy mistake to make ?

[chris-p]

Depends on the lens. The Nikkor lenses I use have 2 settings. Manual/Auto and Manual (M/A and A). The M/A setting allows manual adjustment during AF and I've never had a problem. It might depend on the lens but I would think most newer lenses won't be damaged

[jinky]

Not sure what you`ve got but one of my third party lenses, Tamromn think, warned against doing this. On Canons I understand it`s Ok to manually adjust if you have used autofocus and then keep the button pressed half way vefore you turn. That said I just would not take the risk

[flake]

What you are describing is FTM full time manual focus, and it's something normally found on lenses which use ultrasonic motors.
On non ultrasonic lenses the motor is engaged with the focus and if you try to move it physically then you will force the motor which can result in damage.

[anglefire]

Some non-FTM focus lenses will still manually focus - but in principle its not recommended because it is possible that the gears on the motor to the lens focus mechanism could get stripped. The motor itself won't get damaged.

The reason ultrasonic lenses can be driven in the Auto position, is that there is not a mechanical connection between the motor and the focus mechanism.

[duncan22]

Thanks for the responses which clearly answer my question.
I use own 2 Canon lenses. One is the 17-55mm usm & the other the 55-250mm.
I get used to adjusting the first lens whilst still in AF and on changing lenses sometimes forget to switch to MF hence the reason for asking the question.

[PaulMontgomery]

I suppose the short answer is if you feel resistance when you try it, then stop - you're probably going against the motor. If you don't then its O.K.

Note, that's just my take based on what's been said, don't blame me if something breaks. :-)