Photographic lens system
AssigneeMinolta Co., Ltd.
InventorsSoh Ohzawa, Junji Hashimura
Life of this patent
Estimating the term…
Abstract
A single focal length lens system has a first negative lens element and a last negative lens element. The first negative lens element is disposed at an object side end of the lens system and the object side surface thereof is concave. The last negative lens element is disposed at an image side end of the lens system. The lens system fulfills the following condition: ##EQU1## wherein .phi.f represents the refractive power of the first negative lens element; and .phi.1 represents the refractive power of the last negative lens element.
Claims18
A single focal length lens system comprising:
- a plurality of lens elements including a first negative lens element, disposed at an object side end of the lens system, whose object side surface is concave;
- and
- a last negative lens element disposed at an image side end of the lens system, said negative lens element having an air space between a previous lens element disposed at the object side of the last negative lens element;
- and wherein the lens system fulfills the following condition:
- ##EQU14## wherein;
- .phi.f represents the refractive power of the first negative lens element;
- and
- .phi.1 represents the refractive power of the last negative lens element.
A single focal length lens system comprising:
- a first negative lens element, disposed at an object side end of the lens system, whose object side surface is concave;
- a second positive lens element disposed at an image side of the first negative lens element;
- and
- a last negative lens element disposed at an image side end of the lens system;
- and wherein the lens system fulfills the following conditions:
- 10<.nu.2-.nu.1<30
- 1.6<Nd2
- wherein;
- .nu.1 represents the Abbe number of the first negative lens element;
- .nu.2 represents the Abbe number of the second positive lens element;
- and
- Nd2 represents the refractive index of the second positive lens element.
A single focal length lens system used for an objective lens of a camera, which forms an object image on a film comprising:
- a first negative lens element, disposed at an object side end of the lens system, whose object side surface is concave;
- and
- a last negative lens element disposed at an image side end of the lens system;
- and wherein the lens system fulfills the following condition:
- ##EQU21## wherein;
- .phi.f represents the refractive power of the first negative lens element;
- and
- .phi.1 represents the refractive power of the last negative lens element.
A single focal length lens system used for an objective lens of a camera, which forms an object image on a film comprising:
- a first lens unit including a first negative lens element, disposed at an object side end of the lens system, whose object side surface is concave;
- a second lens unit including a last negative lens element, disposed at an image side end of the lens system;
- and
- an aperture stop positioned between the first and second lens unit, wherein the lens system fulfills the following condition:
- ##EQU22## wherein:
- .phi.f represents the refractive power of the first negative lens element;
- and
- .phi.1 represents the refractive power of the last negative lens element.
Dependencies are inferred from the claim text.