I've been gradually adding photos to my relatively new iMac. Some have wrong dates because the camera lost the automatic date function when the battery was dead and we failed to reset it before taking new pictures. Over the last few months I have successfully changed dates. Today however I made some changes the same way - or thought it was. But I now seem to have some that think they were taken as early as 1564. Didn't realize digital photography has been around so long? Any idea what I'm doing wrong?

Try again. Maybe you did something wrong. And dates before the advent of DSLRs are acceptable. 1564 might be fine if you are photographing artwork and want to show the date of the artwork rather than the photograph.

I've scanned photos and slides and put the dates of the original (film) pictures, going back to the 1920s. I certainly care more about the original picture date than the the date of scanning!