Konishiroku Photo Industry Co., Ltd.

Tomoko Wakabayashi

Hiroyuki Yamazaki

Hisao Fujita

For small type wide angle lenses for use with a compact camera, so-called inverted retrofocus lenses are often used. In this type of lens, the lens can be formed into more compact by increasing a refracting power of a rear unit of a negative meniscus with a convex surface thereof greatly curved toward an image and a front unit on the side of an object. However, this arrangement gives rise to an aberration. This aberration can be compensated by introducing at least one aspherical surface into the front unit and rear unit. In addition, this aspherical lens can be easily produced if it is formed of plastics.

Wide angle lens

This invention relates to a wide angle lens for a compact camera using a lens shutter, in which wide angle lens, a distance from a front surface of the lens to a film surface is short. The lens is a lens of the inverted retrofocus type in which a negative meniscus lens greatly curved toward an image is arranged at the rear of a triplet lens of convex, concave and convex. The second, third and fourth lenses each comprise a plastic lens. Various aberrations are compensated and variation in focal length due to a variation in temperature is also prevented. By the formation of plastic lenses, it is possible to easily form the fourth lens into an aspherical lens.

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Tokyo, Japan

Tomoko Wakabayashi