STM focus ring at AF mode

Hello !

I am new to photography and I recently bought my first DSLR, the new 650D (t4i) and the new canon lens the 40mm f2.8 STM.

I have a question that I wanted to ask and it is : if I am turning the focus ring while the lens is set to AF mode will it do any damage to the lens ?
(I personally believe that it should not do any harm because the focus ring controls the motor that control the focus).

More over when i turn off the camera and the lens is extended it dose not retract back to its normal possiton (as seen in this video : http://www.youtube.com …page&v=YIGbY3UN​N_w#t=289s), does it harm the lens if I push on it to fit back inside ?

thanks ahead Daniel.

Hi.
No, you wont do any damage turning the ring while in AF, but i wouldn't push it back in manually. You will notice that unless you are holding the shutter button half way down the focus ring doesn't do anything.

A lot of us owners have found that if you push the lens barrel in you might find the AF stops working, and the only way to fix this is to take the lens off and re mount it. Not the end of the world but i think it shows that you really shouldn't.

Here's a tip. If you use the back button to focus (look it up if you dont know what this is) you actually get full time MF, even in AF mode.

No need to push it, just turn the focus ring till it is fully retracted.

Generally I would never push the front element of a lens to seat it back, that is just asking for the mechanism to slip out of alignment and break the lens.

Keyan wrote in post #14744272
No need to push it, just turn the focus ring till it is fully retracted.

Just to be clear, the camera has to be on to do this. Quckest way might be to focus on something in the distance before turning the camera off.

No, the STM lens doesn't have manual focus override, so it's not a good idea to try to MF when you have AF set on the lens.

qbfx wrote in post #14744750
No, the STM lens doesn't have manual focus override, so it's not a good idea to try to MF when you have AF set on the lens.

The 40mm STM does have manual focus over ride as long as you keep the shutter button half-pressed. Turning the focus ring will never cause damage because it is 100% electrical focus and it will either focus as you turn it, or it won't focus. If it doesn't focus it is because the lens has gone to sleep or the camera is turned off.