| http://www.w3.org/ns/prov#value | - Varifocals were quite common in the early days of variable-focal-length lenses and are increasingly rare today, if indeed there are any left.A constant aperture lens is a variable-focal-length lens with an automatically-adjusting aperture such that the set apertures (including the widest one) remain constant over the lens's entire focal-length range.
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