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Re: [Canon-10D] Lens no Focus Bruce Ward Tue Apr 03 07:01:42 2012

It's always possible that there is a problem with the lens, I've had 
periodic problems with various lenses.  Do you have the camera set to 
acquire focus with the shutter button in front (the default)?  If so, 
when you use the focus and recompose method, if you let up on the 
shutter button after first acquiring focus, then take the shot, the 
focus is reset when the shot is taken.  Move the focus to the * button 
in back (it's a custom function) and this problem can be avoided.  There 
are also potential problems with the focus-recompose method even when 
done right.  Depending on the FL and the amount of movement done to 
recompose, the focal plane can be significantly shifted to the point 
that things that you thought should be in focus will not be.  I use the 
method, but occasionally will get fooled.

The best way to check the lens is to put the camera on a tripod, turn 
off IS, use a shutter release cable, use center focus point only, and 
shoot a brick wall at several FLs and apertures in good light.  Make 
sure you have a good contrasting object on the wall to focus on.

Bruce Ward

On 4/3/2012 8:38 AM, Darrin J. Calcutt wrote:
> What are the chances that my 18-200 IS F3.5 - 5.6 lens is outs of wack?
> I'm just not happy with the amount of pictures I take that are out of focus.
> Most of the ime I shot with one point of focus, and re-compose.
> Darrin

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