50d auto focus problem

AF lens will not focus on my 50d. Exact same lens WILL af on my 40d. Tried cleaning the contacts but to no avail. Please help

Have you tried another lens.
Is your 50D set to focus with back button.

If all else fails do a reset on your 50D by removing both batteries, leave it for a few minutes then refit them.

Im a nooby. Took battery out for 10 minutes. Cleared all setting using camera menu. Set to af on lens no work. Half press shutter button in AUTO dial mode and the numbers in the view finder stay illuminated and wont take photo. Dont know if back button focus is on or not. Pushing buttons hoping to fluke a result. Have tried other AF lenses that work on my 40d, but none of them work in AF on 50d

You have to take BOTH batteries out of the 50D, this will reset the camera to factory settings and then refit both batteries and autofocus will be triggered by the shutter release as normal.

The second battery is situated next to the main battery in a little slide out compartment.

If this doesn't work then it looks as though the 50D is faulty.

Do you have another lens to test on the 50D? Can you borrow one?

Is the camera new to you? If so, it might be useful to reset the menu and custom functions. You don't need to do a "reboot" (removing the batteries) to do that... In fact, a reboot often won't reset everything to the defaults entirely anyway.

Both in the menu and again in the Custom Functions, there are "Reset Defaults" options. Any settings other than the defaults that you've adjusted will need to be reset afterward.

Or, you could just go in to Custom Function IV, 1 "Operation Others", "Shutter button/AF/ON button" and see if it's set to 0. Default or one of the four other settings. The Default 0. setting will disable back button focusing.

If you decide to do the reboot....

Yes, you have to remove all the batteries. Instructions how to do a reboot are here in this post. Just removing the batteries briefly won't make the camera reboot. You can check if you've gotten a proper reboot by looking at the date/time. They should need to be reset. If not, you didn't get a reboot.

If none of this solves the problem, there are several other possibilities....

1. You didn't mention what lens. Some third party lenses have compatibility issues. They work fine with an older Canon camera, but not with a more recent one. Mostly it's been Sigma and Tamron lenses that have had problems. I have a Sigma 28-75 that works fine on EOS-3 and 10D, but causes 30D and 50D to lock up. (Sigma would update some of the more valuable lenses, but this one isn't worth the trouble.)

2. Try a different lens on the 50D. It it also fails to focus, there's likely a problem with the camera. But if both lenses are older, third party lenses... refer back to 1.

3. Do not set the camera to full AUTO mode (green box). Use M, Av, Tv or P. On some Canon the more automated modes might have a focus lock, that won't let the camera fire until focus is achieved. I don't know if this is the case with the 50D or not... simply have never used those highly automate modes (green box and scene styles on the mode dial)

Hi Guys, thanks for the replies.
Did everything as described in the reboot, and still no auto focus. Cleared all settings that I could find. I tried 3 different canon lenses that work on the 40d, but none of them will auto focus on the 50d. Should I just buy a replacement auto focus motor for the 50d @ $100 and keep it as a backup so I don't have to change lenses? Should I fix it and sell it? What advantages if any, are there for the 50 v 40 other than more MP. Unsure what to do with the 50d.

Dial set @ 'P'
Lenses used
1. Canon EFS 18-55mm @ 1:3.5-5.6
2. Canon EFS 17-85mm @ 1:4-5.6
3. Canon EF 70-300mm @ 1:4-5.6

Any advise is greatly appreciated.

Shayno wrote in post #14860796
Hi Guys, thanks for the replies.
Did everything as described in the reboot, and still no auto focus. Cleared all settings that I could find. I tried 3 different canon lenses that work on the 40d, but none of them will auto focus on the 50d. Should I just buy a replacement auto focus motor for the 50d @ $100 and keep it as a backup so I don't have to change lenses? Should I fix it and sell it? What advantages if any, are there for the 50 v 40 other than more MP. Unsure what to do with the 50d.

Dial set @ 'P'
Lenses used
1. Canon EFS 18-55mm @ 1:3.5-5.6
2. Canon EFS 17-85mm @ 1:4-5.6
3. Canon EF 70-300mm @ 1:4-5.6

Any advise is greatly appreciated.

It sounds like you've tried all the basics and that there must be something wrong with the camera that needs to be repaired. I would suggest shipping it to Canon to get an estimate of what a repair will cost.

Your location is not stated but I'm going to assume that you are in the U.S. Go to this page: http://www.usa.canon.c​om …pageKeyCode=req​uestRepair and fill out the form, print it out, and ship your camera to the recommended location. Repair estimates are free so you have nothing to lose except the cost to ship the camera.

Good luck!

When you say "it does not focus," do you mean that it wont attempt to focus? Or do you mean it has problems obtaining correct focus? Like the lens is "hunting" for focus but cannot lock on subject.

Doesn't attempt to focus at all. I live DownUnda. Is it worth repairing to keep as a backup? Any ideas on repair costs.
Thanks for your help

Reflash the firmware. Sometimes when things are acting up, this can clear the issue. Latest, which was just this past February, is at http://www.usa.canon.c​om …os_50d#DriversA​ndSoftware. Even if you have the latest, I would still do a reflash.

have you actually tried to press the back focus button? Sorry if it's been mentioned that you have, I just didn't see it.

umm, isn't the autofocus motor in the lens?

Check if the af module is blocked by dust or fluff, it's in the bottom of the mirror box, I would use a blower to dust this off.

Do the lenses actually try and focus but don't lock on, or does nothing happen ?

He already stated that it doesn't try.

It's correct that there's no AF motor in the camera. They are always in the lens. He's confusing it with a Nikon or something.

I think all Canon cameras have a fuse for the power supply to the lens. This fuse can blow if you use a lens that's missing the stop pin in the lens mount. If the pin is missing, you can turn the lens too far when mounting it (or if you try a Nikon move for dismounting). That can short circuit the power supply. If this happens, a power board in the camera is replaced (the fuse is integrated on the board).

lol. kind of defeats the purpose of the fuse no?