[LRflex] Re: Erratic AF on Digital Rebel problem
- From: Douglas Sharp <douglas.sharp@xxxxxx>
- To: leicareflex@xxxxxxxxxxxxx
- Date: Thu, 10 Nov 2005 17:36:42 +0100
Hi Javier,
have you tried the different AF modes, sometimes my 300D (Drebel) hangs
up in one of them, I'm not sure which anymore.
1) I've had this happen with a Tamron AF 18-200mm, the Canon 28-135mm
IS, and the bundle-zoom 18-55 EF-S.
Usually when there's very high contrast in the target.
2) Have you inadvertently switched the AF points to a single point? Or,
particularly, a point somewhere at the edge of the frame,
If you're in wide angle mode it sometimes won't focus correctly.
Hope some of this may help you out.
cheers
Douglas
Javier Perez wrote:
>Hi Everyone
>This is a question that may have been asked before. I
>am having a problem with a digital rebel. The AF seems
>to be erratic. Specifically, if I press down on the
>shutter release to activate the AF I get a lock. But
>if I let go and depress again, the lens sometimes
>refocuses. I’m doing the test at wide-open aperture
>with a clear target on a tripod so there’s no
>possibility of camera movement. I use the central
>sensor only. It shows up as an out of focus error in
>the pics. It tends to happen at the wide end of the
>zoom range. I tried the test at about 1 meter at full
>aperture using a Tokina 19-35 and a and a 20-35 L
>Zoom. I also tried the test with a 1v and a 1. The 1v
>and the 1 are rock solid. The focus point doesn’t
>shift no matter how many times I tap the shutter. I
>cleaned the secondary mirror and the inner surface of
>the primary mirror on the DR. It has alleviated the
>problem but it still exists. I looked through dpreview
>but unfortunately those who have seen the problem and
>post on it get flamed by those who refuse to believe
>the problem exists. Was wondering if this is a known
>issue and if the solution is known. BTW: this is NOT
>a backlash issue. That’s to say it’s not caused by
>slight looseness in the helicoid of an AF lens, which
>can cause the focusing ring to register a slightly
>different distance depending on whether the AF locks
>in coming or going. This does not show up in
>photographs. Anyways any advice besides the copout
>“send it in to Canon” is greatly appreciated. I’d like
>to get to the bottom of this annoyance!
>Thanks
>Javier
>
>
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