I have a digital rebel xt and in the past took pictures as large JPEG which have a resolution of 72. I now think I understand that for printing the photo's should be at 240-300 DPI (resolution). Does this mean i should resave all my photos that I am going to print at 300 DPI? I also would like to hear if you save a copy at say 72 DPI and also at 300 DPI for printing.
If you're starting out with a JPEG, make sure that you're editing a copy of the original file.
If you're trying to print the file directly in Photoshop (not via "Print with preview") or with a dumb application, a 72 DPI resolution will yield a very, very large print. An image 3600 pixels across will become 50 inches in print, and of course the print resolution will be poor.
For the sake of simplicity, I suggest that you set your default DPI to 240 or 300, and use that as your working resolution.
Keep in mind that you probably don't want to resample the image when changing the DPI setting or simply the image dimensions in inches/cm.
