| 摘要 |
PURPOSE:To obtain a zoom lens which is less in the numbers of independently moving movable lens groups and constituting lenses, has only one cam groove, and is inexpensive, by moving the 1st and 3rd lens groups under a united condition. CONSTITUTION:The zoom lens of this invention is composed of the 1st lens group G1, 2nd lens group G2, and 3rd lens group G3 and a diaphragm S is united with the 3rd lens group G3 in one body. At the time of zooming, the 1st and 3rd lens groups G1 and G3 move toward an object under a united condition and the 2nd lens group G2 also moves from a side mode W to a telescope mode T. Since the 1st lens group G1 is composed of 2 lenses, one positive lens and one negative lens, the cost can be reduced and, since the 1st and 3rd lens groups G1 and G3 are moved under a united condition, only one cam groove becomes sufficient and the number of the constituting lenses of the entire system can be reduce to 11-12. Therefore, a zoom lens system which is compact in constitution, low in cost, and satisfactory in performance can be obtained. |
