I know you cant record to both the SD & CF cards at the same time.

But when one card is full, does the 5d mk3 automatically switch to the other card? If so do you lose any frames?

Thanks

The 5dmiii does not continue to record from one card to the next. It simply stops when a card is full. There is an option to have the camera automatically switch cards when one is full, but this applies to stills, not live video recording. This and the 29 minute limit mean you really need to watch your recording time.

Thanks Matt