Zoom lens and video camera comprising the same

摘要

A compact zoom lens comprising a small number of lenses, providing an aperture of about F1.4 and a zoom ratio of about 14, with a full angle of view at the wide angle end of 64 DEG or wider. A zoom lens of the present invention comprises, aligned respectively from the objective side, a fixed first lens group (1), comprising a lens with a negative refracting power, a lens with a positive refracting power, and a meniscus lens with a positive refracting power; a movable second lens group (2) to provide zooming effect, comprising a lens with a negative refracting power, a biconcave lens with a negative refracting power, and a lens with a positive refracting power, with at least one surface of these lenses aspheric ; a fixed third lens group (3) with a positive refracting power, with at least one surface of these lenses aspheric ; a fourth lens group (4), movable for compensating the position of the focal plane, with a positive refracting power, with at least one surface of the lenses aspheric. The below mentioned formula (1) is satisfied, $where\; fw\; is\; a\; focal\; length\; of\; the\; zoom\; lens\; operating\; in\; a\; wide\; angle\; condition,\; @\; is\; the\; half\; angle\; of\; view\; of\; the\; zoom\; lens\; operating\; in\; the\; wide\; angle\; condition,\; f1\; is\; a\; focal\; length\; of\; the\; first\; lens\; group,\; f2\; is\; a\; focal\; length\; of\; the\; second\; lens\; group.\mathop{\mathrm{image}}$