Reproduction Ratio
From Nikonians Wiki - FAQs, Photo Glossary, Good Photo Locations, Help
The size of the subject in an image compared to its actual size. As a general rule, for subjects farther away than in macro photography, the focal length of the lens used, divided by the camera to subject distance yields the reproduction ratio. e.g. a 180mm lens focused at 1.8 meters (18000mm) will have a 1:10 reproduction ratio.
