What is a mega pixel? What do they do?

1 mega pixel = 1000,000 pixels (picture elements). It is the digital "dots" that make up a digital photo. The analogy to film photography is the grain size in photographic films and papers. Anything below 200 mega pixels is considered low resolution. If you are cropping pictures, to enlarge them, you will want to set your camera for maximum resolution to compensate for the loss of resolution that results when you crop and enlarge. Ebay is funny in that you may have trouble with large files. Try to send the 10 mega pixel pics (if you camera can go that high), and see if ebay accepts them. You may want to consider using a photo hosting site. The ones that work with ebay allow more pics at higher resolution. The most critical issue you have is that your camera MUST have a "macro" mode that will allow you to photograph your coins up close. That is a lens issue, not a resolution issue. You will also want to set up an impromptu "light stand" with two light sources pointing at your coins at 45 degree angles with a rigid stand to hold the camera facing down.

The 5 mega pixel camera takes photos with better resolution.