XT auto focus problems...

I've noticed, no matter which of my lenses I'm using, that my XT will really struggle to auto focus in anything but bright bright daylight. It'll struggle back and forth, and forth and finally give up. Is there any fixes for this? Changes to make? It does this with my Sigma 17-70, Canon 50 1.8, and the kit lens. It drives me NUTS!

I'm all about manual focus, but sometimes, it's nice to be able to pretty much, point and shoot...

Hmmm... My guess is that there is something amiss. I had a XT for 6 months and never had the type of focus issues you are describing. It would hunt occasionally with the telephotos on and in the dark, but nothing like your problem. Has it done this since day one? Have you got and ERR99s along with the focus problems? What focus setting are you using? How about focus points? One, all? What are you shooting? Does it do it for everything including landscapes?

I have this problem as well.

What I do is switch to MF when it's giving me problems. Or, what you can do as an alternative is to just keep half holding the shutter button down, until it finally stops going back and forth. Then you can snap the photo well focused.

Glad to know I'm not the only one with these problems... I wish I knew how to fix it. It is mostly in darker rooms, but it hunts with my 50mm 1.8 or the 17-70. I use the auto focus in the center (-)

You could try to clean the AF sensors with a blower. You'll find them under the mirror. I had a similar problem. Not quite identical but almoust - with all my lenses many shots turned out to be out of focus. I've tested the lenses and the body with a chart, and find out some shots where back focus, some front focus and some spot on.
After some serious blowing on the sensors, 99% of tests turned out to be spot on, even in low light.
I hope this will help you.

It depends on the situation, the AF difficulty may be normal, as XT is not the best low light AF'ing camera. If you find that your XT has more difficulty AF'ing in the dark than another XT, then it's probably the camera.

For low light settings, try to find the brightiest and the most contrasty object at the distance you want to shoot and use the center AF point as well.

Thank you all very much for the fast replies...

The XT AF is better than the 300D AF but it's not as good as anything else in Canon's range.

But the XT still should be able to focus in many other conditions other than bright bright daylight. That is just not normal.

What camera settings (i.e. ISO, shutter, aperture) are you using?

Just a thought - what metering settings are you using. Don't use the first dial setting which allegedly calculates the depth of field for you. It will never produce a sharp photo.

rhys wrote in post #2815262
The XT AF is better than the 300D AF but it's not as good as anything else in Canon's range.

i wouldn't go as far as saying it's better, after all, both use the same 7 point af sensor. the software controlling the af functions should be newer, so that may bring about more consistant af, though probably not much more accurate

basroil wrote in post #2816287
i wouldn't go as far as saying it's better, after all, both use the same 7 point af sensor. the software controlling the af functions should be newer, so that may bring about more consistant af, though probably not much more accurate

I think that the difference is in the speed of Digic as opposed to DigicII. I know that my old XT focused noticeably faster than my sons Rebel. He now has that XT and that was the one thing he also immediately noticed, that and power up speed, and much less hunting.

I don't know about the other two lenses, but the AF on the 50mm 1.8 is notoriously bad, I find that mine hunts around quite a bit too.

It does it on any setting really. I mean, from the green point and shoot box to manual...