IMAGING OPTICAL SYSTEM

摘要

PROBLEM TO BE SOLVED: To provide an imaging optical system which has a short back focus by employing a telephoto-type power arrangement and yet offers a wide angle of a standard lens and good optical performance, secures sufficient peripheral brightness, and is suitable for both as an image capturing optical system and a projection optical system.SOLUTION: An imaging optical system LN comprises, in order from the object side, a front group GrF having positive power, an aperture stop ST, and a rear group GrR having negative power. A lens located next to the aperture stop ST is a cemented lens L45. The system offers a half view angle ω of no less than 22.5° and satisfies the following conditional expressions: 3