Re: *ist D AF and snow?

[John Coyle]

On the other hand, I was at the beach the other day and my *istD was 
focussing without problem on different waves (no more than 6-9 inches high 
under an overcast sky) as I was shooting dolphins hunting trevalley.  I was 
impressed that the focus point indicator showed the changes from one part of 
the frame to another happening with commendable speed and accuracy.

John Coyle
Brisbane, Australia
----- Original Message ----- 
From: "Don Sanderson" <[EMAIL PROTECTED]>
To: <[EMAIL PROTECTED]>
Sent: Saturday, November 20, 2004 5:57 PM
Subject: RE: *ist D AF and snow?


Any AF camera will have trouble with snow,
AF works by judging the contrast (Difference
between light and dark areas) of the subject.
Anything that is all one color with no shadow
lines or prominent texture or color difference
to create contrast will be IMPOSSIBLE for AF
to lock on to.
Also, anything that is too bright or too dark
will give AF fits.
Even the human eye needs to find some kind of
feature or shadow area to focus on.
When I want my AF lenses to retract all the way
to infinity for storage I just point the camera
at a wall or ceiling that is all one color.
Fools the AF everytime, causing the lense to go
from one extreme to the other.
Don
-----Original Message-----