Ditto what VikingOSX already posted.
When you look at your list of photos in a Finder window, are you looking at a "Date Added" or "Date Last Opened" column instead of "Date Created" or "Date Modified?"
If you believe you are seeing something in error, please show us. Select one of the photos in the Finder and do GetInfo. Take a screenshot of the General and More Info portions of the GetInfo window. Then open that same photo in Preview, do Tools > Show Inspector, click the EXIF tag and do another screenshot showing the Date Time Digitized. Post both screenshots here.
The Created Date in the GetInfo window should match the Preview Inspector window's Date Time Digitized date. They come from the EXIF data supplied by your camera and should have the same value.
While you're at it, also take a screenshot of the Finder window showing the above photo; be sure to include the column headers in the screenshot. Post here.