| 摘要 |
PROBLEM TO BE SOLVED: To provide an imaging optical system with enhanced imaging performance and a shortened entire optical length. ! SOLUTION: The imaging optical system comprises, in order from the object side, an aperture stop, a first lens with positive refractive power, a second lens with negative refractive power, a third lens with positive refractive power, and a fourth lens with negative refractive power, and satisfies the following conditional expressions: 2.0<r5/f<6.0 (1) and 0.10<d7/f<0.20 (2), where r5 is the radius of curvature of the second lens on the image surface side, d7 is the air space between the third lens and the fourth lens on the optical axis, and f is the focal distance of the entire imaging optical system. ! COPYRIGHT: (C)2014,JPO&INPIT |
