At our school we have been syncing our ipads to one Macbook Air-the time has come where that Air if filling up of useless photos. Rather than have to delete them each time they sync is there a way to tell the iPads to sync photos only to an external hard drive?

We have 30 iPads, running on a bretford sync cart.
Not sure if I have to do this process for each one or just a general setting in iTunes or iPhoto?

Thanks
JU