Canon 400D. Autofocus problem

Try pressing the "Menu" button and disable "Active-D Lighting", also try setting the "Autofocus mode" to "Single". When the camera is off, press the shutter release and twist with the zoom know back and forth. Hopefully that fixes it! It worked for my P500 with the same problem.

Check the camera and make sure that autofocus is on on both the lens and the camera, if they both have switches.
Check the autofocus mode, whether it's single, or continuous. If it's in single, it'll only focus once per time you half-press the shutter release, continuous it'll continue to focus as long as your finger is down.
If that doesn't work, try another lens and see if the problem still persists. Otherwise, contact the manufacturer, as it could be hardware related.
Remember, cameras do not autofocus well in low light.

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

Hey mate,

I've been having the same problem. It annoyed me during a day out once.

Set the camera in one of the Creative Modes.
-> Then go to Menu (the button on the left of the screen)
-> Setup 2 (thats the furthest menu on the right)
-> Custom Functions (3rd option down)
-> Go to function 4 and change it to "0: AF/AE LOCK"

Hope that helps mate :)

Cheers
Baghdad_boy

If you set the camera on "manual", it assumes you focused manually and allows you to press the shutter without having to stop half-way. Check your settings.

Hello,
It's possible that the reason the "pictures turn out fairly good" is that your f-stop is set high enough that even though the image isn't properly focused, you have enough depth-of-field to bring your subject into "near focus". Does your lens try to focus back and forth when you half-press the shutter? If not, double check that the lens is in autofocus and not manual focus. You can also try cleaning the contacts between the lens and camera. Take the lens off, and then one-at-a-time clean the contacts on both the lens and the camera, using a clean pencil eraser. Gently rub the contacts. Be sure to hold the item upside down so that the eraser debris falls on to the table, not into the camera body or lens!

If none of this helps the autofocus may have become damaged and you need to have the lens and camera looked at by Canon Repair.

in that case my tipp don't mess with it further, pack it in (the body ) and send it to canon for a repair see www.canon.com and cntact them about this isue ask what the cost will be and send the camera in by secured and insured parcel service like tnt (www.tnt.com) describe on paper what ypi have done so that a expensive technician knows where to look.

Backfocus problems will be magnified when using wide aperture lens with shallow depth of field, nice lens btw. Camera's adjustments for manual and autofocus are inside mirror cage behind mirror, and you dont want to risk getting dust on sensor or damaging sensor. Qualified camera repair shop or sending to canon for adjustment would be my suggestion.

The longest part of the shutter delay is caused by the autofocus mechanism. Most cameras will let you press the button half-way down and wait until the autofocus is locked. Then wait for the action to occur. When you press the button the remaining distance, there will be a shutter delay of about 0.2 seconds before the picture is taken. Using that technique will let you capture action shots. There is no way to improve shutter delay on any particular camera. The newer digital cameras are showing improvement in this area. Some are achieving autofocus lock in 0.4 seconds and shutter delay of an additional 0.1 seconds.