Just curious if some of the Canon L lenses have full time manual focusing why is there an option to switch between autofocusing and manualfocusing?

-- No Spam Please (Please@nospam.net), February 04, 2002

Answers

All current AF capable L series lenses have FT-M. FT-M is great for prefocusing and touching up AF if it misses. However, true manual focusing is frequently needed, especially when using a tripod for macro work, astrophotography, still life and landscapes with hyperfocal distance. It would be counterproductive to have AF screwing up your focus setting every time you touch the shutter button to meter or take the picture.

-- Puppy Face (doggieface@aol.com), February 04, 2002.

The full benefit of FTM doesn't come into play until you set your Canon to the custom function that allows you to move autofocus off the shutter button (usually Custon Function 4). That way, autofocus is only activated when you press the separate autofocus button, not when you press the shutter button. In that case, FTM is truly wonderful because you can autofocus, but then manual focus, then trip the shutter without having the autofocus refocus on something else. Otherwise, you do need the on-off switch on the lens to keep the lens from autofocusing every time you hit the shutter button.

-- Peter (pphan01@hotmail.com), February 05, 2002.