VARIABLE POWER LENS

• Main Authors: AOKI NORIHIKO, SHIMIZU SEIJI
• Format: Patent
• Language: English
• Published: 10.02.1994
• Edition: 5
• Subjects: OPTICAL ELEMENTS, SYSTEMS, OR APPARATUS; OPTICS; PHYSICS

PURPOSE:To excellently compensate various aberrations and make the lens compact by composing a 2nd lens group of two negative lenses and one positive lens and making the focal length at the wide-angle end which satisfies specific conditions shorter than the diagonal length of an image pickup plane. CONSTITUTION:This lens includes a 1st lens group G1 with positive refracting power, the 2nd negative lens group G2, and positive lens groups G3-G5 arranged on a more image side than the alone lens groups. This lens system is varied in power by moving the group intervals of the 1st lens group G1 and 2nd lens group G2, and the 2nd lens group G2 and lens groups G3-G5 on the more image side than them from the wide-angle end to the telephoto end; and the 2nd lens group is composed of the two negative lenses and one positive lens and conditions -0.3<f12w/fT<-0.1 and ¦D23/f2¦<0.08 are satisfied. Here, f12w, fT, and f2 are the composite focal length of the 1st and 2nd lens groups at the wide-angle end, the total focal length at the telephoto end, and the composite focal length of the 2nd lens group and D23 is the air gap between the 2nd and 3rd lenses in the 2nd lens groups from the object side.