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.
A mode on some compact cameras that lets you shoot extreme close-ups from distances as short as 1cm. However, this is always at the wideangle end of the zoom range where the magnification is lowest. It can also be difficult to photograph timid subjects like insects at this distance.
Strictly speaking, macro photography where a real-life object is captured at the same size on the sensor. So a bee 10mm long would form an image 10mm long on the sensor. True macro photography needs dedicated ‘macro’ lenses.
Many cameras and some telephoto lenses offer a ‘macro’ button or mode. This is rarely the same as true macro photography at 1:1 magnification. Instead, ‘macro’ is simply used as another word for close-up. This is the macro button on a Fuji X30 compact camera.