Wide angle lens system and camera
View Patent ↗There is provided a wide angle lens system configured to obtain excellent image forming performance even in a half field angle region of 40 degrees to 50 degrees. A wide angle lens system is constituted of a first lens having a negative refractive power, a light path bending member having no refractive power, a second lens having a positive refractive power, an aperture which adjusts a light amount, a first cemented lens formed by cementing a third lens having a positive refractive power and a fourth lens having a negative refractive power, a fifth lens having a positive refractive power, and an optically equivalent member which functions as a faceplate of an optical low-pass filter and a solid state imaging element.
1. A wide angle lens system, comprising, in order from an object side:
a first lens having a negative refractive power and at least one aspherical surface;
a bending member for bending an optical path;
a second lens having a positive refractive power;
an aperture which adjusts a light amount;
a first cemented lens formed by cementing a third lens having a positive refractive power and a fourth lens having a negative refractive power; and
a fifth lens having a positive refractive power;
wherein a surface of at least one lens arranged on an image plane side of the aperture is aspherical; and
wherein the wide angle lens system has a half field angle of approximately 40 degrees to 50 degrees.
2. The wide angle lens system according to claim 1 wherein said aspherical surface of at least one lens arranged on the image plane side of the aperture is arranged in a last lens closest to the image plane and has a shape with which a positive refractive power is gradually weakened or a negative refractive power is gradually intensified from the optical axis toward the periphery.
3. The wide angle lens system according to claim 1 wherein the last lens which constitutes the wide angle lens system and is arranged at a position closest to the image plane is formed of a resin lens.
4. A camera comprising: a wide angle lens system defined in claim 1 and a solid state imaging element arranged on an image forming surface side of the wide angle lens.