Writing to multiple memory cards on a canon 5d mark iii whilst filming Hi i have a canon 5d mark ii and it has 2 slots for memory cards one cf and one sd.I'm planning on doing some filming outdoors so was wondering if the CF card is full will it automatically start writing to an SD card or am i better off using multiple cf cards?
As far as I am aware it will write to both cards at the same time (dual redundancy), I dont think you are going to be able to write from one card to the next.

Using 2 cameras would always be a better option as you will then have multiple angles and or if you have a failed recording on one camera you still have a backup