B+W close-up lenses are high-quality optical magnifying lenses which shorten the close-focusing distance of the lens. It allows the lens to go closer to the subject than before and to achieve a larger image scale. An increase in the exposure time is not necessary.
This lens has a diopter of +10 and a 100mm focal length. As it fills the frame of the 35mm format, life size to somewhat larger than life size pictures are possible.
The NL10 Close-up lens IS NOT front threaded and is not meant to be used in combination with other close-up lenses