Patent ID: 8400719

Claim:
A lens system having an F number equal to or smaller than 2.4, wherein a positive lens element is disposed closest to an object side; a diaphragm disposed in a widest air space in the lens system; and wherein in a rear unit including all lens elements disposed on the image side relative to the diaphragm, an aspheric surface is provided on a lens element closest to the image side or on a lens element second closest to the image side; and the lens system satisfies the following conditions: 0.05< L — 1/ L — TH< 0.21 1.5< L — TH/Y< 8 where, L_I is an interval from a lens surface located closest to the object side to a lens surface located on the object side relative to the diaphragm, L_TH is an interval from the lens surface located closest to the object side to a lens surface located closest to an image side, and Y is a maximum image height.