Reproduction ratio

Reproduction ratio is a term used in macro photography to indicate the degree of magnification. A ratio of 1:1 is usually considered the minimum for ‘true’ macro photography. This means that an object is reproduced at exactly the same size on the sensor or film surface as it is in real life. If the first number is higher, e.g. the reproduction ratio is 2:1, it means the lens can reproduce objects at twice life size. If the second number is larger, e.g. 1:2, it means objects are reproduced at half their actual size.