D50 After autofocusing stops it still isn't quite in focus.

You should check two switches.

First, on your lens, be sure it's set to M/MA not M. That puts the lens in auto focus mode.

On the camera there should be a switch that shows C/S/M. If switched to M, it's on manual focus. Change this to S for single auto focus or C for continuous auto focus.

That's called an "autofocus assist lamp". When you prepare to take a picture in low light, the autofocus can struggle to lock on to your subject. The lamp you talk about, illuminates the subject for a moment, so that the autofocus can 'see' when correct focus has been achieved.

It is indeed annoying, but this is the price you pay for sharp photos (it's not possible to wait for the flash to go off, and focus in that moment). One 'solution' would be to turn the focus assist lamp off and live with the poor results. Another 'solution' would be to switch to manual focus. Or you could let the camera focus normally once, apologise to your subject, turn the focus to manual without changing it, and then taking more pictures without the annoyance (but you might have got a good picture the first time, anyway).

Set the camera to "spot focus".

I figured out that when changing lenses my finger must have hit the little switch and flipped it over to manual focus. I changed it back and it now works. Thanks.

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.

replace the lithium battery 1.5X2 . then press then ok good, but does not work the drive motor was broken.

Auto-focus technology on this camera is controlled by several contacts on the mount that physically mate with other contacts on your lens. It sounds like your mount may be malfunctioning due to wear and tear (if cleaning does not work). This is between $100 and $300 fix depending on which part(s) need replacement.

First try another lens on the body and see if the problem is the lens or the body,if its the body the autofocus mirror could be out of adjustment, if its the lens, it sounds like the lens took an impact and needs a pro repair. you should be able to set body to manual focus and focus lens to infinty.

Same happened to mine ,Its almost as though the motor has dis-engaged.I SOLVED MINE BY FORCING THE FOCUS RING WITH AUTOFOCUS ENGAGED THIS SEEMS TO HAVE RE ENGAGED THE MOTOR .HOWEVER BE CAREFUL I HAD LITTLE TO LOSE MINE WAS STILL UNDER WARRANTY WHEN I DID THIS.Its perfect since.

In the custom settings, you can program the "ok" button of the 4-way controller to disable AF. It's kind of a handy little trick. It's called "Ok button when shooting" or something.