The B+W 55mm Close-Up +4 SC NL 4 Lens offers the ability to achieve macro-like results with camera lenses that have 55mm front filter threads. A close-up lens is a magnifier that optically decreases the focal length of a camera lens placed behind it. This effect lessens the minimum focus distance between the camera lens and a subject. Magnification can then be obtained by decreasing the distance between the subject and the combined camera lens and close-up lens.
The magnifying power of a close-up lens is indicated by its diopter strength. A close-up lens with a higher diopter number provides more relative magnification and can be combined with other close-up lenses to increase, or fine-tune the macro effect. This close-up lens has a diopter strength of +4. Diopter strengths of +1, +2, +3, or +5 are also available where this close-up lens type's effect becomes progressively stronger with each diopter strength number increase.
To prevent internal ghosting and reflections, each glass surface of this lens includes one layer of anti-reflection coating. B+W close-up lenses are constructed from Schott glass for increased optical clarity. This close-up lens features an F-Pro brass filter ring for durability as well as jamming prevention.