Digital SLR Camera Basics
Minimum Focus Distance
The minimum focus distance is the shortest distance at which a lens can focus. In the case of digital SLR cameras, the distance to the subject is measured from the focal plane mark on the camera body, not from the front of the lens.
Focal plane mark
- ※The illustration is an artist's conception.
The lens can not focus at distances shorter than the minimum focus distance. It is useful to know how close your lens can be to the subject and still focus.
Different lenses have different minimum focus distances. The minimum focus distance of an AF-S DX NIKKOR 18–55 mm f/3.5–5.6G VR lens is 0.28 m or 0.92 ft. (a little over 11 inches; this information appears on the lens as ∞–0.28 m/0.92 ft.).
The minimum focus distance of an AF-S NIKKOR 50 mm f/1.4G is 0.45 m (about 1.5 feet or 18 inches; the minimum focus distance is shown in the lens focus distance display).
Reproduction ratio (or photographic magnification) is the ratio of the size of the image on the image sensor to the actual size of the subject. For example, if the length of a 5 cm object on the image sensor is 1 cm, the reproduction ratio is 1 : 5 (0.2 ×). The higher the reproduction ratio, the larger the size at which the subject is photographed. Micro lenses support high reproduction ratios, making them a good choice for photographs of flowers and other small objects (note that micro lenses can be used for more than close-up photography: they also offer superior reproduction at long distances).
A comparison of normal and micro lenses
The micro lens offers greater reproduction ratios than normal lenses.