Pete I'm taking 2 x 2TB external drives and downloading the cards to both of them at the end of the days shootingThe scary part is he is taking his D800 .......
They are a card eater - lol
Neil,
What are you doing about your images once they are on the cards?

With that as your backup then 4 or 5 cards will be fine.. It's more down to how much you plan on using the D800.... My 'worst day' (lol) at an air show I took 8400 pics and came to 640 Gb. It was a good day however.....![]()