"How large can I get this print?" Part One.

Working at a professional photo lab, there are certain questions we hear a lot.     The number one question:  "How large can I print this digital image?"     The answer:   "It depends."     If the image is not sharp as a 4 x 6, it will NEVER look better as a larger print.    Enlarging the image will only make a soft focus photo look softer (or blurry).   If the focus and exposure are correct, one of the best ways to insure you will be satisfied with an enlargement is to always have your camera set to shoot in high (or large) resolution.    Whether you have a DSLR or a digital point and shoot, the camera will allow you to set your preference to shoot in various resolutions.    The downside to shooting with a higher resolution is that the images will take up more room on your hard drive.    The upside is that if you shoot a photo you love, you'll be able to have a great looking enlargement.     Are there "rules of thumb" in terms of how many megabytes a photo needs to get a great enlargement?     There are.     I'll post those in part two.