I’m still trying to decide if its best to photograph or scan my coins. I’ve used my camera in the past because it is more flexible, offers higher resolution, captures relief better than a scanner, and produces natural looking images.
Here are a few rules of thumb I’ve found to work well for photographing medals, coins, and exonumia:
1) Use the highest quality setting available on your camera (ie; SHQ instead of SQ).
2) Resize the photographs to a smaller size before sharing them. This tends to concentrate the detail, and it also cuts down on server space use and reduces page load times. I’ve resized my photos to 450 pixels wide, but I have copies of the original images available on request.
3) Clean the camera lens. Any dust will show up as noise on the resulting image (or, worse, look like damage to the coin surface). Be careful to use non-abrasive cloth and avoid scratching the glass for the same reason.
4) Use a dark background, perhaps even a complimentary color. This makes focusing easier, and it also gives the image more eye appeal.
5) Shoot at an angle. This not only uses parallax to capture the depth details, but it prevents the flash from reflecting right back into the CCD. A 45 to 60 degree angle is usually enough to put the flash spot on the background instead of the surface of the coin.
6) Consider using a lightbox or diffuse natural light. This reduces artifacts in the image and can really show coins in the best light. Artificial light is usually ‘colder’ than sunlight (lightbulbs produce a narrow range of the visual light spectrum), so natural light makes coins look more golden (or red). You may also consider using full-color light bulbs to achieve a similar effect.