| 摘要 |
Zoom lenses having a positive unit facing the long conjugate and consisting of a cemented doublet and a single element therebehind; a negative unit movable for zooming and consisting of a negative element and a negative doublet concave toward each other; a second positive unit movable for zooming and consisting of a single component including at least one positive element; and a stationary rear unit consisting of a triplet or triplet derivative wherein any element additional to three is a positive element. The zoom lens has a zoom range greater than 5x, a total coverage exceeding 48 DEG at some zoom position and an f-number faster than f-1.2 when the number of elements in the lens is 12 or less and faster than f-1.6 when the number of elements is 10 or less.
|
