| 摘要 |
The invention relates to a bent type zoom optical system comprising a positive first lens group having a reflecting member and remaining fixed upon zooming and a second lens group adapted to move upon zooming, and having a high zoom ratio and a short entire-length, and an imaging apparatus or the like incorporating the same. The zoom optical system comprises the positive first lens group G1 adapted to remain fixed upon zooming and the negative second lens group adapted to move upon zooming. The positive first lens group G1 comprises, in order from the object side, a negative single lens, a reflecting member P and a positive lens unit. The zoom optical system satisfies condition (1) for prevention of fluctuations in the entrance pupil position, condition (2) about the focal length of the first lens group G1, and condition (3) for putting in order the shape of the negative single lens in the first lens group G1.
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