JPH03265811A

JPH03265811A - Zoom lens

Info

Publication number: JPH03265811A
Application number: JP6548590A
Authority: JP
Inventors: Hiroki Nakayama; 博喜中山
Original assignee: Canon Inc
Current assignee: Canon Inc
Priority date: 1990-03-15
Filing date: 1990-03-15
Publication date: 1991-11-26

Abstract

PURPOSE:To obtain the zoom lens which is reduced in size on the whole and has an about '2' of power variation ratio and excellent optical performance over the entire power variation range by specifying the refracting power values of three lens groups and the lens constitution. CONSTITUTION:The zoom lens has the three lenses which are a 1st group 1 with negative refracting power, a 2nd group II with positive refracting power, and a 3rd group III with negative refracting power in order from the object side, and the power is varied from the wide-angle end to the telephoto end by moving the 1st group I - 3rd group III to the object side. Then the 2nd group consists of three lenses, i.e. a positive lens which is convex to the object side, a negative biconcave lens, and a positive biconvex lens. Consequently, the zoom lens which has an about '2' of power variation ratio and the high optical performance over the entire power variation range although the overall lens length is shortened is obtained.

Description

【発明の詳細な説明】（産業−にの利用分野）本発明はレンズシャッターカメラ、ビデオカメラ淳に好
適な小型の３つのレンズ群を４１するズームレンズに関
し、乃にバックフォーカスを短くすると共にレンズ全長
（第ルンズ面から像面までの距＃）の短縮化を図った変
倍比２程度のズームレンズに関する６のである。Detailed Description of the Invention (Industrial Field of Application) The present invention relates to a zoom lens having three compact lens groups suitable for lens shutter cameras and video cameras. No. 6 relates to a zoom lens with a variable power ratio of approximately 2, which aims to shorten the overall length (distance # from the lens surface to the image surface).

（従来の技術）(Conventional technology)

Claims

[Claims] (1) It has three lens groups in order from the object side: a first group with negative refractive power, a second group with positive refractive power, and a third group with negative refractive power, and has a wide-angle lens. The magnification is changed from the end to the telephoto end by moving the first, second, and third groups toward the object side, and the second group has a positive 21st lens with a convex surface facing the object side, and both lenses. A zoom lens comprising three lenses: a negative 22nd lens having a concave surface, and a positive 23rd lens having both convex surfaces. (2) The principal point distance between the first group and the second group at the wide-angle end is E1W, the principal point distance between the second group and the third group is E2W,
The distance between the final lens surface of the first group and the first lens surface of the second group at the wide-angle end is L1W, and the distance between the final lens surface of the second group and the first lens surface of the third group is L2.
W, the second and third lens groups as the magnification changes from the wide-angle end to the telephoto end.
It is characterized by satisfying the following conditions: 1<E1W/L1W<5 1.2<E2W/L2W<2.5 0.4<M2/M3<0.7, where the movement amounts of the groups are M2 and M3, respectively. The zoom lens according to claim 1. (3) The focal lengths of the second group and the third group are f2 and f3, respectively.
, where fw is the focal length of the entire system at the wide-angle end, the following conditions are satisfied: 1.5<|f3/f2|<3 0.35<E1W/fw<0.6 zoom lens.