Bellows
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Accordion-like device mounted on cameras that allows the lens to move towards or away from the film/sensor-plane for greater magnification than with the lens alone. Usually employed for close-up or macro work. Nikon bellows are the PB-3, PB-4, PB-5 and the latest model PB-6 which can be extended further for higher magnification with the PB-6E extension bellows.
