i have a SanDisk Ultra 8GB card with 15MB/s transfer that i've been using for a while. My family is going to europe, so i went out today and bought 2 - SanDisk Ultra Plus 16GB cards with 48 MB/s transfer. The empty 16 GB card says i have 1412 photos to shoot before full, the 8GB card says i have 1694 photos to shoot before full. Doesn't make sense to me. I am using them in a Casio Exilim EX-Z1000 in case that makes a difference.