Title:
【発明の名称】変倍ファインダー
Document Type and Number:
Japanese Patent JP2586520
Kind Code:
B2
Abstract:
PURPOSE:To easily obtain high optical performance in high variable magnification all over the variable magnification range by satisfying the value of a focal distance which is the shortest of the respective synthetic focal distances of 1st and 2nd lens groups, interval between the 2nd lens group and a 3rd lens group at the above- mentioned time and the lateral magnification of the 2nd lens group in all the variable magnification areas with a specific condition. CONSTITUTION:The title finder has three lens groups such as the 1st lens group 1 with the negative index of refraction, the 2nd lens group 2 with the positive index of refraction and the 3rd lens group 3 with the positive index of refraction in order from an object side and also it has an objective lens 10 with the positive index of refraction as a whole and an eye piece lens 6 with the positive index of refraction as a whole so as to perform the variable magnification by moving the 2nd lens group 2 to an object side. In such a case, the condition of an inequality I is satisfied when it is supposed that the value of the focal distance which is the shortest of the respective synthetic focal distances of the 1st and 2nd lens groups 1 and 2 is f12w, the interval between the 2nd and 3rd lens groups 2 and 3 at the above-mentioned time is 123w and the lateral magnification of the 2nd lens group 2 in all the variable magnification is beta2. Thus, the excellent optical performance can be obtained in high variable magnification all over the variable magnification range.
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Inventors:
NAKAYAMA HIROKI
Application Number:
JP27496587A
Publication Date:
March 05, 1997
Filing Date:
October 30, 1987
Export Citation:
Assignee:
CANON KK
International Classes:
G02B13/12; G02B13/18; G02B15/163; G02B23/14; G02B25/00; (IPC1-7): G02B25/00; G02B15/163
Domestic Patent References:
| JP61156018A | ||||
| JP627017A |
Attorney, Agent or Firm:
Takanashi Yukio