Canon’s Error 99: the Man, the Myth

Common Causes of Err99

I’m listing these in my own perceived order of frequency, combining our experience at LensRentals with reading countless online Err99 reports. The list has been revised after further information from Precision Camera about actual causes they see during repair. One important thing they reminded me of: when we see Err99 on the screen, the camera actually has more information about the cause of the error internally. A repair shop can read this information from the camera and often determine the cause with complete accuracy.

• Lens/camera electrical contact failure
• Lens circuit (AF or IS) failure
• Camera electronic circuit failure (see below)
• Battery or Grip problems
• Broken or stuck lens aperture diaphragm – Note: this most often happens only when the lens is completely stopped down. If you have questions about the lens, shoot it both wide open and stopped down. If Err99 appears when stopped down, its an aperture issue.
• Older third-party lens with incompatible electronics
• Jammed or damaged camera shutter curtain
• Mis-formatted or damaged card
• Damaged or corroded cell within camera battery
• Failure of the sequence motor—according to precision this is unusual, but does occur, especially in older cameras that have been through a shutter replacement.
• Corroded battery or camera contacts
• Incorrectly mounted battery grip, particularly if it’s too loose
• Camera/hot shoe electrical contact failure
• Moisture condensation within camera or lens (or corrosion occurring days or weeks after moisture exposure)

Most of us cannot define in-camera circuitry failure more specifically than “it went to Canon for repair”, but a few skillful individuals have disassembled their Err99 frozen cameras and reported things like loosened solder splats that were causing shorts, ribbon cables not firmly seated in their connectors, loose metal shields in the camera that could move enough to short or ground an electrical part, etc. If you’ve never seen the insides of a digital SLR, there are an amazing amount of electronic connections packed into basically no space in there.

Author: Roger Cicala

I’m Roger and I am the founder of Lensrentals.com. Hailed as one of the optic nerds here, I enjoy shooting collimated light through 30X microscope objectives in my spare time. When I do take real pictures I like using something different: a Medium format, or Pentax K1, or a Sony RX1R.