On the right side of this slide, you can see there is IPTC information, while below, there is no camera or EXIF information. This is what happens when someone crops a photo and resaves it under a new name and does not bother to save the EXIF data. The same thing can happen when images are scanned.

Does that make me sound "grumpy?" What I am interested in is that who will ask what questions 30-50 years from now about this photograph. The computer you are reading this on will be gone, the web site will be gone or at least in a whole different form, likely I will be gone (remote, although possible), but the image will be.