WIDE-ANGLE OPTICAL SYSTEM

摘要

Provided is a wide-angle optical system having a picture angle exceeding 180 degrees and in particular, a small-size and bright ultra-wide-angle imaging optical system and projection optical system having a small F number. The ultra-wide-angle imaging optical system or the projection optical system having a picture angle exceeding 180 degrees and formed only by transmission planes includes: a front group (G<SUB>f</SUB>) formed by at least one meniscus lens (L1) having a negative focal distance; an aperture (S); and a back group (G<SUB>b</SUB>) formed by at least two lenses having a positive focal distance. The transmission plane of at least one plane of the front group (G<SUB>f</SUB>) is formed by an extended rotary free curved surface.