Err 99 Hey all, Just got the 10-22 lens and put it on my 20D and at first it wouldnt focus, check and it was in AF mode, then my camera turned off, so I flipped the switch from off to on, all my settings were reset, and I tried to use the lens again and get Err 99. Any ideas?

Error 99 is a result of an electronic communication problem normally between the lens and the camera body.

Use a red pencil eraser to "polish" the contacts even if they look clean do it again.
Take care to keep dirt out of the camera and lens bodies.

Another thing is often times the camera firmware needs to be updated to move on from this.

Another thing is the CF cards? The 20D was in an era where pretty well the larges CF card was a 2gig,I use several 1gig however if you have updated your cards to say an 8gig the firmware just can't handle the card.

Okay moving on clean the lens and body, update firmware, make sure the CF card isn't beyond the camera capabilities and last if all that stuff didn't work the it's possible the actual sensor is really dirty and needs cleaning.

The worst case scenario is that the shutter has failed. The Canon 20D is only good for 60,000 actuation's.

Hope this give you a few options

Err 99 could mean several different things, such as... Memory Card, Lens or Lens contacts....
Here's what you can try:
Remove the memory card an enable "shooting with out memory card" and see if you still get the error. If it works your memory card is bad. Try another lens if you can. Clean the lens contacts with a pencil eraser (be careful not to get eraser dust in the camera body or in the lens). Worst case scenario is, Err 99 could be related to the shutter failing which would mean a trip to Canon.
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Make sure your camera is set to Auto mode (top left knob). Check your lens and make sure it is switched to "auto" and not "manual"(sliding switch near base of lens). Make sure your lens can rotate and move without being obstructed. Clean the lens contact by removing the lens and use 99% alcohol or lens cleaner sparingly to clean off the metal contacts.
You can also check your viewfinder focus, it has a small dial upper right, that you can fine tune to focus to your own eyesight. If it is way off, your view will always appear to be out of focus.
Hope that helps.

The AF motor is hunting. Clean the contacts on the end of the lens and the camera body with a pencil eraser and try again.

Error 99 is known as Abnormal Mirror operation. Follow the link for help;EOS-1D Mark III/EOS-1Ds Mark III: AF Accuracy Adjustment
EOS-1D Mark III/EOS-1Ds Mark III: Abnormal Mirror Operation (Err 99)

It should be noted that the AF accuracy adjustment advisory is in addition to the previous EOS-1D Mark III AF mirror adjustment service notice. Free repairs are being offered for customers affected by the "Err 99" mirror problem, and Canon is also providing free AF accuracy checks and adjustments for customers experiencing problems with soft focus when using any but the central AF point.

Finally, Canon Japan has published a new manual entitled "EOS-1D Mark III AI Servo Auto Focus Manual" aimed at helping owners understand and get the most from their AF system.

Press the AF button on the top of the camera (to the right of the window) to select an AF mode & make sure the M/A (Manual / Auto focus) switch on the lens set to "A"

More info below:

http://www.kenrockwell.com/nikon/d80/af-settings.htm

Check the pins in the memory card slot. It sounds like a pin is bent causing a short.

If two cameras are doing it, I would suggest the contacts on your lens are dirty.

Try the following diagnosis steps for solving ERR 99 issues : -

To isolate the cause of the issue, do the following: -
1. Turn off the camera.
2. Remove the lens, battery, and CF card.
3. Allow the camera to sit without power for approximately 20 minutes.
4. Insert only a fully charged battery, and turn on the camera.
5. Depress the shutter button as you would to take a picture.

Does the “ERR 99" message appear? If so, the camera may be faulty and requires a service. If it does not, then: -
1. Turn off the camera.
2. Insert the CF card.
3. Turn on the camera.
4. Format the CF card in the camera.
5. Depress the shutter button as you would to take a picture.

Does the “ERR 99" message appear? If so, then the CF card is faulty. Try a different card. If the message does not appear: -
1. Turn off the camera.
2. Clean the gold contacts on the lens by GENTLY rubbing them with a pencil eraser or soft cloth. Keeping the camera face pointing down, also clean the gold contacts on the camera, being careful that you do not let any debris fall into the camera body.
3. Reattach your lens.
4. Turn on the camera.
5. Depress the shutter button as you would to take a picture.

If the “ERR 99" message only appears when one particular lens is attached, then that lens should be examined by a service technician.
If you see the “ERR 99" with a different Canon lens attached, then the camera is faulty and should be serviced.

1. Turn off the camera.
2. Remove the lens, battery, and CF card.
3. Allow the camera to sit without power for approximately 20 minutes.
4. Insert a fully charged battery, and turn on the camera.
5. Depress the shutter button as you would to take a picture.
Does the “ERR 99′ message appear? If it does, then the camera should be
serviced. If it does not, then please proceed to the next set of steps:
1. Turn off the camera.
2. Insert the CF card.
3. Turn on the camera.
4. Format the CF card in the camera.
5. Depress the shutter button as you would to take a picture.
Does the “ERR 99′ message appear? If so, then the CF card is the most
likely source of the issue. Try using a different card.
If the message does not appear, please complete the following steps:
1. Turn off the camera.
2. Clean the lens contacts by gently rubbing them with a pencil eraser
or soft cloth. Be careful that you do not let any debris fall into the
camera body.
3. Reattach your lens.
4. Turn on the camera.
5. Depress the shutter button as you would to take a picture.
If the “ERR 99′ message only appears when one particular lens is
attached, then that lens should be examined by a service technician.
If you see the “ERR 99′ with a different Canon lens attached, then the
camera should be serviced.

I get error 99 sometimes on my 20 D but it?s usually to do with a lens that is attached. Sigma lens have been known to cause error's. If it's not that or dirty contact on the lens then it could be a more serious problem. I would at least check it out with a canon dealer/repair centre.