Re: Auto-focus on digital SLRs.

Steven Green <steven.green30@[EMAIL PROTECTED]
> wrote:
>I am new to the auto-focus world, both my film cameras are manual focus.
>I just got my hands on my sister's Digital Rebel XT (DRXT) to just learn 
>some basics of the camera and see what features I really like.
>
>One thing I am developing a disliking for is auto-focus.
>On the DRXT it sometimes goes into fits zooming in and out then refuses 
>to snap a picture.

This can happen if there isn't enough light or the lens isn't fast enough.
Most manufactures explicitely limit AF to lenses faster than approx.
f/5.6. 
> I find the auto-focus slow and a pain in the ass.

Normally autofocus on a dSLR is almost instantanious, at the order of a
fraction of a second. And normally they don't hunt either because of the
phase detetction system used, which allows a direct, non-incremental
adjustment.

>I understand that the speed of auto-focus can be a function of the lens 
>and the effectiveness on the amount of light (if I understand this 
>correctly)

Quite so. Unfortunately you don't tell us anything about what lenses you
are
using. There is quite a difference between a 20+ year old screw-driver
type
and a modern ultra-sonic AF.
Or are you by any chance using auto-focus with a closed apperture? That
would explain your problems, too.

Of course, you can always turn off AF easily enough with the flip of a
switch.

jue