Canon Rebel Xti Wont autofocus

there is not much to do by yourself, sounds like an electronic problem, please refer to next service center.

It sounds like you might be too close to whatever it is you're trying to take a picture of. Each camera lens has a minimum focus distance listed on it that determines how close you can get to something and still take a picture. Page 45 of the XTi manual talks about minimum focusing distance and describes the camera's behavior.
It's also possible that there is not enough light for the lens to focus. In this situation you might have to flip the switch on the lens to manual focus to take your picture.
So, either try moving further away so the lens can focus or use the manual focus.
In case you are interested, here is a website that discusses the minimum focus distance. Even though the website talks about Nikon cameras you will still be able to use the information.
Also, on page 160 of the XTi manual there is a section titled "When Autofocus Fails" that will give you an idea of what your camera is doing.
Cheers and good luck. :)

If it is a dark scene and the camera cannot detected edges well the autofocus will either move around a lot or simply will not focus and thus wont expose. You will just have to manually focus or use the flash

I have the same problem - it wont take pictures in auto focus mode but will in manual focus?? Help!!

First of all i would recommed to reset the camera . If it Still does not solve the problem then the Autofocus assit System has some problem.

Please try the reset first from the menu

I dropped my camera and thought the autofocus broke. It turn out that it swithed from autofocus to manual focus. There's a switch on the lens. Check if that's your problem too.

I think it might be a lens issue.
make sure you change the macro option. the macro must be activated if you are taking a picture of something which is close to the camera. if it's not activated, the picture will not be focused.
The same will happen if the item is far and the macro is ON.

excuse me if this is a dumb question but you wouldn't believe the things people do...., but in manual mode are you actually manually trying to move the lens? as manual mode means just that you take hold of the lens and turn it. If it wont turn it sounds like the lens is jammed and needs returning/repairing.

if taking hold of the lens and turning it works for manual mode, take the lens off and clean the gold contacts on both the camera and the lens with a pencil erasor this may bring the auto focus back to life, switch back to auto and try again, if not its most likely the lens but take the body to a canon store and try another lens just to double check the body is ok

drop me a line if i can be of further assistance

best of luck

AI should be focusing. You really can't change many settings when you are shooting in auto mode. Is the lens in AF mode?

I'm sure you have long since returned from vacation!

Hope this helps!

hi sneakers
the camera is firing the flash to help it auto focus,the only way to stop it find an area of the picture that has more light/contrast or switch to manual focusing.
regards
ian