Canon 99 error or how to disassemble Canon 1785 IS USM and replace

Take a picture. If you get err 99 your camera is broken and you will need to send it in for service. Insert cf card if that gives you err 99 when you take a picture then its the cf and replace it. Replace lens and take a picture. If err 99 then its the lens or the contacts. Clean your lens contacts on both the camera and the lens.. \$\begingroup\$ After step 4 I'd try the same again with any clock battery removed as well, replacing it with a new one and cleaning the contacts. I think this battery also maintains shot count and several other things but that might only be true in older models. It's also worth leaving it some time with the batteries out. \$\endgroup\$ - Chris H

The "Error 99" 'Shooting is not possible' is shown on the Canon Camera's LED while trying to take a picture and it usually indicates an issue with the. Treat it as if were a specially treateda and coated, glass lens filter, one which could be easily scratched. I think cotton has too much of a potential to leave lint behind.