Focusing Basics

[RDY]

Hi,

Could you please share your tips on adjusting focus using a Canon DSLR and lenses. Should the camera be on the manual setting all the time in order to adjust focus? Is there danger in not being in manual mode (say in AV) and to be shifting focus on a lens?

Thanks,
RD

[inkista]

Exposure mode is independent of focusing mode. I wouldn't worry about being in M mode for that. You use M mode for precision, control, and repeatability of exposure.

I tend to use only the center AF point, and do a halfpress and recompose for most times I'm using autofocus. I use manual focus for more precision if I'm shooting macros, or using a manual focus lens.

If I'm shooting fast-moving action, I use back-button autofocus.

[RDY]

Thanks. As a follow-up, is safe to adjust a lens in any mode and without the lens being in manual mode?

[i speak in math]

If you want to manually focus, put the lens in manual focus mode. The camera modes are not related to the focusing mode of the lens. M or Av mode on the camera are in regards to exposure and do not have anything to do with the focusing mode on the lens.

[inkista]

Originally Posted by RDY

Thanks. As a follow-up, is safe to adjust a lens in any mode and without the lens being in manual mode?

Depends on the lens. Yes, to adjust the focus in any (exposure) mode on the camera. No to adjust it without the lens being in manual focus mode. To be safe, make sure it's switched to MF, first, unless you know the lens can do full-time manual focus (FTM).

If the lens has ring-type USM (or is the 50mm f/1.4 USM) it has FTM, and you can adjust the focus manually while the lens is still in AF, but for a lens like the 50mm f/1.8 II, which is non-USM, or the EF-S 55-200 USM, which uses the micromotor version of USM, you can actually damage the lens by adjusting manual focus with the lens switched into AF mode.

This list shows which Canon USM lenses are ring type and which are micromotor.

[Doug Pardee]

Originally Posted by inkista

This list shows which Canon USM lenses are ring type and which are micromotor.

A simple shortcut for Canon-brand lenses: if the lens says that it's USM and it has a focus distance indicator, then it has full-time manual focusing.

Of course, the manual-focus-only lenses (TS-E and MP-E) also can be focused manually at any time.

[RDY]

Thanks! You saved my lenses!

[RDY]

Thank you!