Olympus Corporation

Akio Michinaka

Hisashi Goto

Takahiro Amanai

An optical system comprises, in order from the object side, an aperture stop, a first lens with positive refracting power, a second lens with negative refracting power, and a third lens, both surfaces of the third lens are an aspherical surface in which refracting power varies in accordance with distance from the optical axis in such a way that the both surfaces have a convex shape facing toward the object side in the vicinity of the optical axis and have a concave shape facing toward the object side in the vicinity of the outer circumference, and the following conditions (1) and (2) are satisfied:2.2&#x3c;&#x3c;7&#x2003;&#x2003;(1)&#x2212;0.04&#x3c;&#x3c;0.04&#x2003;&#x2003;(2)where dis the thickness of the first lens on the optical axis, dis a space distance between the first and second lenses on the optical axis, f is a focal length of the whole of the wide angle optical system, and fis a focal length of the third lens.

Wide angle optical system and image pickup apparatus using the same

A wide angle optical system is formed by, in order from the object side, an aperture stop, a first lens with positive refracting power, a second lens with negative refracting power, and a third lens. Both surfaces of the third lens are an aspherical surface in which refracting power varies in accordance with distance from the optical axis in such a way that the both surfaces have a convex shape facing toward the object side in the vicinity of the optical axis and have a concave shape facing toward the object side in the vicinity of the outer circumference, and the following conditions (1) and (2) are satisfied:0.1&#x3c;&#x3c;0.65&#x2003;&#x2003;(1)&#x2212;0.04&#x3c;&#x3c;0.04&#x2003;&#x2003;(2)where dis a space distance between the second and third lenses on the optical axis, dis the thickness of the third lens on the optical axis, f is a focal length of the whole of the wide optical system, and fis a focal length of the third lens.

A wide-angle optical system comprises, in order from its object side, a stop, a first lens (L) having positive refracting power, a second lens (L) having negative refracting power and a third lens (L) that is an aspheric lens. The third lens is configured such that as viewed in a lens section including an optical axis, a portion thereof near the optical axis is in a meniscus shape convex on an object side thereof, and an object side surface and an image side surface thereof at a peripheral site are in a meniscus shape convex on an image side thereof. The optical system satisfies the following conditions (1-1) and (1-2).&#x2212;0.40&#x3c;3&#x3c;0.15&#x2003;&#x2003;(1-1)0.30&#x3c;7/7&#x3c;2.0&#x2003;&#x2003;(1-2)where f is the focal length of the whole wide-angle optical system, and fis the focal length of the third lens. When Lm stands for a light ray passing through the center of the stop at an angle of 36&#xb0; with the optical axis, and Pmstands for a point at which Lm passes the image side surface of the third lens, hcis supposed to be a distance from Pmto the optical axis, and hpis supposed to be a distance from a convex apex Ppof the image side surface of the third lens to the optical axis.

Growing community of inventors

Hachioji, Japan

Akio Michinaka