Title:
WIDE ANGLE PHOTOGRAPHIC LENS
Document Type and Number:
Japanese Patent JP3247756
Kind Code:
B2
Abstract:
PURPOSE: To obtain a wide angle photographic lens of wide angle of view with small distance between a first surface and a final surface, high performance, and large aperture of F/2.8 class by constituting a lens system of a front group with positive refracting power and a rear group consisting of a diaphragm and with negative refracting power, and specifying relation between the focal distance of the whole system and that of the rear group.
CONSTITUTION: This wide angle photographic lens is constituted of the front group of three groups/four lenses consisting of a positive joint lens joining a positive meniscus lens(r 1, r 2) whose convex surface is faced with an object side, a biconcave negative lens (r 3. r 4), a positive lens(r 5, r 6), and a negative lens(r 7) sequentially observing from the object side, and the rear group consisting of the diaphragm r 8 and a meniscus lens(r 9, r TO) whose convex surface is faced with an image side. Also, the lens is constituted so as to satisfy an equation 5<&verbar fR&verbar /f assuming the focal distance of the whole system as (f) and the focal distance of the rear group as fR. By employing such constitution, it is possible to negate spherical aberration and coma aberration in the front and rear groups and to reduce distance between the first surface and the final surface of the lens system.
Inventors:
Koji Ogata
Application Number:
JP7742093A
Publication Date:
January 21, 2002
Filing Date:
March 12, 1993
Export Citation:
Assignee:
Olympus Optical Co., Ltd.
International Classes:
G02B9/34; G02B13/04; (IPC1-7): G02B13/04; G02B9/34
Domestic Patent References:
| JP6426811A | ||||
| JP59195212A | ||||
| JP5934509A | ||||
| JP5691206A | ||||
| JP57116313A | ||||
| JP59147312A |
Attorney, Agent or Firm:
Kanji Mukai