LENS WITH ULTRA-WIDE FIELD AND LARGE APERTURE

摘要

Disclosed is a lens with an ultra-wide field and a large aperture, relating to digital cameras and camera lenses, constituted by at least three parts of a first lens group G1, a second lens group G2 and a third lens group G3 arranged in sequence from an article side to an image side. When an article moves from infinity to a close range, the first lens group G1 is fixed and the second lens group G2 and the third lens group G3 move so as to focus. The following conditions are satisfied: 1.2≤(|F12|+S)/LB≤2.5(1); 0.8≤(|F12|+S)/(tanω×LB)≤1.3(2), wherein F12 is the resulting focal length of the first lens group G1 and the second lens group G2 when the article is at infinity; S is the distance between the frontmost end face of the first lens group on the article side and the diaphragm in the infinity state; LB is the distance between a face closest to an image plane and the image plane in the infinity state; and ω is the angle of the half-angle of view of the optical system. Provided is an ultra-wide field lens having an angle of view of over 110 degrees, being small in size, high in performance and low in costs.