Greg Lynch wrote:
>I've never ever on ANY camera
>had the viewfinder show me what's in and out of focus without using DOF
>Preview. Unless the whole image is out of focus. Part of the viewfinder
>image in focus, and the rest out of focus (like when the autofocus fails)
>is something totally foreign to me. What am I missing????
To slightly restate Paul's original observation, he was saying that at the
*widest possible aperture* for a given lens (for example, f/1.4 on the 50mm
f/1.4 lens), there should be no need to depress the DOF preview button to
see what would or would not be in focus at that aperture setting. This is
because the DOF preview button works by stopping down the lens to the
desired aperture, but, if the lens will be used wide open, there is no
stopping down to be done.
Paul was puzzled (correct me if I'm wrong, Paul), by his observation that
everything in his viewfinder is in focus, even though the lens is wide open
(DOF button not depressed). Yet, if he were to take the photo at the
wide-open aperture, parts of the photo would be out of focus. If Paul's
observation is correct, something strange must be happening.
But, if the camera is working correctly, the observation is incorrect. I
just did a reality check with my EOS 3 and 50mm f/1.8 lens (I don't have
the f/1.4). I focused on an object at the closest possible focusing
distance, and saw that objects in the background were *out of focus*, just
as they would have been in the photograph if I had taken the photo at
f/1.8. I did not depress the DOF preview button. It's important to focus on
something really close, and have background objects that are at least a few
feet away, otherwise it might be hard to see what is in focus and what is not.
Gerry
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