We take along four cameras when we travel. Two of them are Canon G15s. When I download photos, I am not sure which photos Ginny took and the ones I took. Unfortunately, the EXIF data doesn't seem to have serial numbers. The light came on in the attic and I decided to program our names into the Creator line of the EXIF. So I went outside for a test, and it worked. Should have thought of that a long time ago.