WIDE-ANGLE IMAGING LENS

An optical system (100A to 100D) includes, in order from an enlargement conjugate side to a reduction conjugate side, a front unit (101A to 101D) including a plurality of lenses, an aperture stop (ST), and a rear unit (102A to 102D) including a plurality of lenses. A projection characteristic of the optical system representing a relationship between a half angle of view and an image height on an image plane satisfies a predetermined condition.