Telephoto lens system
AssigneeNippon Kogaku K.K.
InventorSei Matsui
Life of this patent
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Abstract
A telephoto lens system having a relatively large aperture is composed of six lenses collected into four lens members, successively arranged, from the object side of the system to the image side, as follows: a first lens member including a positive lens whose convex surface faces the object side; a second lens member including a negative meniscus lens whose convex surface faces the object side and, a positive meniscus lens cemented to the negative meniscus lens; a third lens member including a positive lens whose convex surface faces the image side, and a biconcave lens cemented to the positive lens; and a fourth lens member consisting of a positive lens. The aberrations of the telephoto lens system of the invention are reduced even though the aperture is relatively larger than the apertures of prior art lens.
Claims8
A telephoto lens system having an aperture ratio of approximately 1:2 and a telephoto ratio of approximately 1.0, the system comprising four members successively arranged, from the object side of the system to the image side, as follows:
- a. a first lens member including a positive meniscus lens whose convex surface faces the object side;
- b. a second lens member having positive refractive power and including a negative meniscus lens whose convex surface faces the object side, and a positive meniscus lens cemented to the negative meniscus lens;
- c. a third lens member having negative refractive power and including a positive lens whose more curved surface faces the image side, and a biconcave lens cemented to the positive lens;
- and
- d. a fourth lens member including a positive lens.
Dependencies are inferred from the claim text.