Err 99 on Canon Digital SLRs · Apr 29, 01:53 PM by Simon Mackie
So you just changed lenses and go to take your picture, but the camera locks up, with the dreaded words “Err 99” on the screen. What just happened? Error 99 means that camera has had a problem, but it’s not sure what it is – not very helpful!
Canon suggest you try switching the camera off and switching it back on again, or removing and replacing the battery. This may help you, but if the problem keeps occurring, there’s two things that seem to cause this error the most: old third-party (Sigma or Tamron) lens and dirty contacts.
Old third-party lenses
If attaching a particular lens to the camera always causes the problem, but it’s fine with other lenses, it may be that that particular lens is not compatible with your camera. You might be able to send it back to the manufacturer to have the chip updated – this is called rechipping. It should fix the problem. Try getting in touch wity the relevant support department and see what they say:
If the lens is too old to be rechipped, you’re probably best off trying to sell the lens ad get a newer replacemnt.
If the contacts that pass information between your camera and the lens’s electronics are dirty, this may also cause the “Err 99” message. You can try carefully cleaning the contacts on your camera body and on your lens. One method (which I first found at Richard’s Notes) to try is to use eraser on the end of a pencil. Be very careful – you don’t want to bend the pins on your camera!
I’ve labelled the contacts on this picture:
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