| 摘要 |
A photographic optical system is constructed by arranging, subsequently from an object side toward an image plane side, a first lens (E1) structured by a negative lens of a negative meniscus type which faces a powerful concave surface, formed aspherical, toward the image plane side, a second lens (E2) structured by a negative lens of a negative meniscus type which faces its weak convex surface toward the object side, a third lens (E3) as a positive lens of a both convex type, an aperture stop (FA), a cemented lens structured by attaching a fourth lens (E4) as a positive lens of a both convex type and a fifth lens (E5) as a negative lens of a both concave type together in close, and a sixth lens (E6) as a positive lens of a both convex type in which both surfaces thereof are formed aspherical. The first lens (E1) to the third lens (E3) structure a front group (GF), and the fourth lens (E4) to the sixth lens (E6) structure a rear group (GR). The rear group (GR) is moved together with the aperture stop (FA) to be extended so as to perform focusing.
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