Can I turn off AF on my lens?

[tarves57]

Hi, I've just paid for a Canon 75-300 IS USM lens online. However, I came across a review where the customer said there was no fulltime manual focus on this lens. Does that mean I cannot use manual focus at all? (I find it preferable to USM on small subjects). What do they mean by "fulltime"?

Thanks
Susan

[chris.bailey]

I have that very lense and it has full manual focus so I dont quite know what that review meant.

[chris maddock]

All Canon EF lenses can be manually focussed - there is a switch on the lens marked AF and MF.
However, some have full-time manual focus - which means you can adjust the focus without having to switch the lens to the Manual setting.
From your question I suspect you're after closeup or macro subjects - for that, I would switch to manual focus anyway.

KRs
Chris

[DonCoon]

What "full time manual focus: means is that even with the lens set to Auto Focus you can use the manual focus ring to change focus.

This is a feature limited to most lenses with ring-type USM focusing. The 75-300 USM has a micro-motor USM and thus can't do "full time manual focusing." You have to physically switch to Manual Focus to manually focus the lens. Not a big deal, IMHO.

[wolverine]

Lenses that have FTM, means that evenif the AF/MF button is set to AF, manual focus is still possible. On non USM lenses without FTM, in order to manual focus, the AF/MF button has to be set to MF.

[wtlloyd]

That lens is usuable in either auto-focus or manual focus. It does not have full time manual focus.

Full time manual focus allows for final manual adjustment after autofocus, while the lens is still switched to autofocus mode.

Thus, some lenses allow you to have your cake and eat it too. :-)

[wtlloyd]

Yike, where'd all those replies come from?!!

[tarves57]

Thanks guys! So I can turn off the AF (therefore turning off the USM) and work it manually. Perfect.

Susan