Old Toad wrote:
After exporting a photo to the EHD download and use EXIF Viewer for Mac OS X to view the EXIF Image Created date to see if it's the same as that in Photos.
You can also use Preview.app's "Inspector" tool (first item on Preview's "Tools" menu) to view Exif date metadata embedded in photo files. In fact, depending on the file type, the device, & software used to create the digital image, you usually can see quite a few differently named dates embedded in the file, some in the Exif panel & others in the IPTC panel or even the TIFF one (if present).
For example, in the Exif panel, you would probably see both "Date Time Digitized" & "Date Time Original." For a digital camera, for obvious reasons the two dates will normally be the same, but for photos that originally were shot with a film camera they might be different. In the IPTC panel, you might see three entries, a "Date Created," a "Digital Creation Date," & a "Digital Creation Time." This should be the same date-time metadata as in the Exif panel, but displayed using the IPTC tags. You probably would also see a "Date Time" entry in the TIFF panel if the image file is JPEG or TIFF, & that also corresponds to the Exif "Date Time Digitized" tag.
But as already mentioned, these image date-time metadata values are different from & independent of the ones you see in Finder or anything else that displays the file's date-related metadata, which is stored in the filesystem on the hard drive. The latter are managed by the OS & are not stored inside the file, & may be considerably different from the ones stored inside the file.