ZOOM LENS

• Main Author: FUKAMI SEIJI
• Format: Patent
• Language: English
• Published: 02.09.1994
• Edition: 5
• Subjects: OPTICAL ELEMENTS, SYSTEMS, OR APPARATUS; OPTICS; PHYSICS

PURPOSE:To make the whole lens system compact, to shorten a c/ range and to effectively correct variation in aberrations at the time of making into a wide viewing angle and high variable power by specifying the focal distance of the whole system at a wide angle end, zooming and an effective photographing screen. CONSTITUTION:The 2nd group V with negative refractive power for variable power is changed in an area including equal image forming magnification at the time of variable power operation and the 1st group F with positive refractive power has at least two lenses and three lens groups, i.e., the 11th group F11 having negative refractive power as a whole fixed at the time of focusing, the 12th group F12 with positive refractive power which is moved to the image surface side at the time of focusing from an infinite object to a close range object and the 13th group F13 with positive refractive power fixed at the time of focusing. When it is defined that the focal distance of the whole system at the wide angle end is fw, zooming is Z and an effective photographing screen is IS, conditions expressed by 8<=Z and 0.53<=fw/IS<=0.79 are satisfied.