| 摘要 |
A zoom photographic optical system having a broad vari-focal range which comprises, in order from a side of an objective lens system, at least a first positive lens unit, a second negative lens unit and a third positive lens unit, moves the second lens unit and the third lens unit for changing a magnification from a low magnification position to a high magnification position so that an airspace between the first lens unit and the second lens unit at the high magnification position is shorter than that at the low magnification position and an airspace between the second lens unit and the third lens unit at the high magnification position is longer than that the low magnification position, forms an intermediate image between the first lens unit and the second lens unit at the low magnification position, and satisfies the following conditions (1) and (2): 1<=FH/FL<=3 (1) 3<=MGH/MGL<=20 (2)
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