I'm trying to set up my mother's iPhone 4S for iCloud storage. The only data I want it to backup are the camera roll photos, of which there is only 1.7GB of data. However, it won't allow me to do this, it says the "next backup size" is 5.6GB, despite the fact that there isn't really anything else that should be being backed up. Everything else that is an option to back up is set to OFF. Why is there such a large discrepancy in size?