Topic Author
Posts: 1373
Joined: Tue Jun 27, 2000 5:01 am

Canon 300D Autofocus Mirror Problem

Fri Jul 24, 2009 6:51 pm

I'm looking for some advice on a problem that's just cropped up on my old 300D/Digital Rebel. This camera has served me well and is probably nearing the end of its service life, but since I've gotten a new 40D my young son has inherited it and I'd like to keep it going so he can hone his skills with it.

Based on some Internet research I've done, it appears I have a problem with the autofocus mirror. The first symptom I experienced was that all images taken with the camera had the bottom half blacked out. I took off the lens and noticed that there's a small mirror behind the main mirror that remains hanging down when I lift up the main mirror. With the camera in this state the autofocus works fine, but I get the black bottom half. I'm guessing this secondary mirror is also supposed to snap up at the instant the shutter is released, and that isn't happening. It remains hanging below the main mirror, blocking half of the image sensor - that's what's causing the blacked-out image halves.

I can lift up this secondary mirror with my finger such that it snaps back up against the main mirror. This solves the blacked-out image problems, but when in that state the autofocus doesn't work. The camera works just fine in manual focus mode, though.

Any thoughts on a quick fix here? If it were me using the camera I'd probably live with manual focus, but it's useful for my 7-year-old son to have autofocus while he concentrates on learning other aspects of photography.

As far as repairs go if this goes that far, has anyone dealt with Precision Camera? They're based not far from where I live.
Topic Author
Posts: 1373
Joined: Tue Jun 27, 2000 5:01 am

RE: Canon 300D Autofocus Mirror Problem

Fri Jul 24, 2009 7:03 pm

Looks like there are other threads on this topic, and it does appear the camera needs service.

So, let's change the direction of this thread: has anyone dealt with Precision Camera? Their base rate is $180 plus tax.
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RE: Canon 300D Autofocus Mirror Problem

Fri Jul 24, 2009 7:17 pm


Precision Camera fixed my a700 when the antishake died (under warranty). They had it back to me in less than a week. I dropped it off at their Enfield office and they UPSed it back to me. Mark Soares is a good guy and they run a tight ship (IMO). They'll also clean the sensor, adjust the autofocus accuracy, etc.

It sounds like the return lever for the secondary mirror is broken - it should lift up along with the main mirror when the main mirror lifts - even if you lift it manually with your finger. Something as simple as a tab could be broken. I don't know the exact intricacies of the 300D's mirror box but it's probably not all that different from other double reflex mirror designs in AF cameras.
From the Mind of Minolta
Topic Author
Posts: 1373
Joined: Tue Jun 27, 2000 5:01 am

RE: Canon 300D Autofocus Mirror Problem

Sat Jul 25, 2009 10:32 pm

Thanks, Dan. Dropped 'er off this afternoon and they did promise to do some adjustment and sensor cleaning in addition to fixing the main gripe. They also said it shouldn't be more than 3-5 days, so we'll see how it goes. Shouldn't be a major fix in any event.

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