How large is the target? Is it distinct from a contrast perspective from the background? My thinking is it's related to the size and accuracy of the center-point AF spot on the DR versus those on the pro model film bodies. Can you test a 10D or 20D as well? And is this the DR or the XT?
Just some thoughts, tomp > -----Original Message----- > From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] On Behalf Of > Javier Perez > Sent: Thursday, November 10, 2005 7:24 AM > To: [email protected]; [EMAIL PROTECTED] > Subject: EOS Erratic AF on Digital Rebel problem > > 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 > * **** ******* *********************************************************** * For list instructions, including unsubscribe, see: * http://www.a1.nl/phomepag/markerink/eos_list.htm ***********************************************************
