The minimum focusing distance (MFD) is defined by the nearest point a lens is able to focus on. With primes the MFD is an unequivocal measurement, but with zooms the MFD may depend on the focal length used.
The minimum focusing distance is measured from the object (being focused on) to the film/sensor plane (not to the front of the lens). The distinction is significant as – considering the FFD plus the length of the lens (plus the optional hood) – the distance from the film plane to the front of the lens may easily be in excess of 10 centimetres.
In effect, the MFD (together with the lens’ focal length) determines the lens’ maximum magnification.« Back to Glossary Index