ZOOM LENS AND VIDEO CAMERA COMPRISING THE SAME

摘要

A first group of lenses (11) having a positive refractive power and fixed with respect to the image plane, a second group of lenses (12) having a negative refractive power and a variable power action when moving along the optical axis, a diaphragm (15) fixed with respect to the image plane (17), a third group of lenses (13) having a positive refractive power, and a fourth group of lenses (14) having a positive refractive power and movable along the optical axis so as to keep the image plane (17) moved when the second group of lenses (12) and the object move in a fixed position from a reference plane are arranged in this order from the object. The second group of lenses (12) comprises two negative lenses and a positive lens; the third group of lenses (13) comprises two positive lenses and a negative lens; and the fourth group of lenses (14) comprises a lens. Each of the second to fourth groups (12 to 14) has at least one aspherical surface. With this configuration of as few as ten lenses, aberrations including the chromatic aberration can be corrected well, realizing a zoom lens having an angle of field of 62 DEG or more.