| 摘要 |
A variable aperture lens has a fixed aperture stop inside the lens and a variable aperture stop located outside the lens. When the lens is operated at its widest effective aperture, the effective aperture is defined by the fixed aperture stop. When it is operated at its narrowest effective aperture, the effective aperture is defined by the variable aperture stop. This permits highest corrections for the widest aperture but with a lens that is free of the cleaning and other difficulties of a variable interior aperture.
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