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Why poblems with auto focus in program mode?


Greetings: I have a Canon 350 EOS and have purchased a Canon EF 24-105 f/4L IS USM lens. If I using auto focus while in shooting in the auto mode the auto focus works fine. Shooting from a tripod, not moving the camera but switching to program mode the lens has difficulty focusing. I have tried various combinations of shutter speeds, apatures, and ISO settings but to no avail. I have tried it with other lens and experience the same problem.
TIA
Glenn


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February 07, 2006

 

Justin G.
  I've read the IS lenses to have problems while mounted on a tripod. If I remember correctly you should turn the IS off when shooting on a tripod. I don't want to spread "ill-informed" information considering I'm a "rank beginner" but I've read this before and it could possibly be the problem. Try that and wait for others who have the lens/camera to respond. Sorry if this didn't help any.


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February 07, 2006

 

Jon Close
  The IS/tripod problem is limited to lenses with the earliest version of IS. The EF 24-105 f/4L IS USM has the latest version that should work fine when tripod mounted, but turning it off couldn't hurt. Per Canon's Technical Report on the 24-105, "The same image stabilizer effects can be attained when using a monopod as in hand-held shooting. There are no restrictions on using a tripod." Also see http://www.dlcphotography.com/TripodAndIS.htm for more info.

Note that in the Basic modes (Auto-green box, and other icons) the camera overrides any manual settings and forces auto-selection of the focus sensors and usually AI Focus mode. When you switch to a Creative mode (P, Tv, Av, M), then the autofocus mode and sensors are whatever has been selected.

Plus if the lighting is dim, the Basic modes will automatically pop up the flash and flicker it as an autofocus assist light. In the Creative modes this is not automatic and you must manually pop-up the flash to get AF assist.


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February 08, 2006

 

Sharon King
  Hi Glenn,

Are you still having problems focusing your lense? I just purchased the same lense and am having the same problem. I find it has a very difficult time focusing in Auto, Program and manual mode. It seems so slow. I also have had my IS on. Have you found it helped to turn it off when using a tripod? I am a little disappointed in it, I thought I was buying an excellent lense!


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October 29, 2006

 

Philip M. Snyder
  Hi everyone,

I also had a problem with a different lens and my canon 20D auto focus. I did some research and there was a couple of a problems that people had listed but what ended up being my problem was that the lens stopped down to F/6 or higher while I was trying to auto focus. It was not letting enough light in to perform the auto focus function.

I tested this theory out and found that when ever I stopped down the lens in manual or any setting really it would then not focus very well or go through the range 2 or three times before stopping somewhere (Usually not the right somewhere).

I would suggest try this out with your lens and different F/stops and see if that is the problem.

Best wishes to all,

Flipper


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November 18, 2006

 
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