| 摘要 |
<P>PROBLEM TO BE SOLVED: To provide an inexpensive variable power optical system having a compact size and a small F value and having high optical performance with favorably corrected chromatic aberration. <P>SOLUTION: This variable power optical system comprises, in order from an object side, a positive first lens group G1 that is fixed when varying power, a second lens group G2 varying the power by moving along an optical axis Z, an aperture that is fixed when varying the power, a positive third lens group G3 that is fixed when varying the power, and a positive fourth lens group G4 that corrects and focuses an image plane position when varying the power. The second lens group G2 is disposed with, in order from the object side, a negative lens, a positive meniscus lens having a concave surface facing the object side, a biconcave lens, and a positive lens. The variable power optical system is configured to satisfy a prescribed conditional expression related to a focal length of the second lens group G2, the Abbe number of the positive meniscus lens of the second lens group G2, and a moving distance of the second lens group G2 when varying the power from the wide end to the tele end. <P>COPYRIGHT: (C)2012,JPO&INPIT |
