Trouble Shooting an iSight http://support.apple.com/kb/HT2090
Has info for Firewire Externals and Internal iSight/FaceTime cameras
The only real difference between an internal iSight and and FaceTime Camera is tha Name change by Apple.
As Mac OS models change so do components and later cameras are capable of more (pixels on the whole)
Do you have Add-ons that worked in Earlier OS version that have not been updated ?
iGlasses would a global one that might affect you.
It would be useful to know if it ever worked in OS X 10.6.8 for you ?
Please, if posting Logs, do not post any Log info after the line "Binary Images for iChat"
iMac 2.5Ghz 5i 2011 (Mountain Lion 10.8.2)
G4/1GhzDual MDD (Leopard 10.5.8)
MacBookPro 2Gb (Snow Leopard 10.6.8)
Mac OS X (10.6.8),
Couple of iPhones and an iPad
"Limit the Logs to the Bits above Binary Images." No, Seriously