02-12-2014 08:22 AM
Your camera isn't recognizing a lens. Check that your lens is fully installed and/or check that contacts are clean.
02-12-2014 09:02 AM
F00 usually means there's no contact with a lens or the lens has no built in chip. Is it a real Canon lens or an after market? This happens quite often with off-brand lenses.
Otherwise make sure the little spring loaded contacts are all "springing".