Abstract: 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<d2/d3<7??(1) ?0.04<f/f3<0.04??(2) where d2 is the thickness of the first lens on the optical axis, d3 is 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 f3 is a focal length of the third lens.

Abstract: 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<d2/d3<7??(1) ?0.04<f/f3<0.04??(2) where d2 is the thickness of the first lens on the optical axis, d3 is 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 f3 is a focal length of the third lens.

Abstract: 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<d5/d6<0.65??(1) ?0.04<f/f3<0.04??(2) where d5 is a space distance between the second and third lenses on the optical axis, d6 is the thickness of the third lens on the optical axis, f is a focal length of the whole of the wide optical system, and f3 is a focal length of the third lens.

Abstract: 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<d2/d3<7??(1) ?0.04<f/f3<0.04??(2) where d2 is the thickness of the first lens on the optical axis, d3 is 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 f3 is a focal length of the third lens.

Abstract: 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<d5/d6<0.65??(1) ?0.04<f/f3<0.04??(2) where d5 is a space distance between the second and third lenses on the optical axis, d6 is the thickness of the third lens on the optical axis, f is a focal length of the whole of the wide optical system, and f3 is a focal length of the third lens.

Abstract: A wide-angle optical system comprises, in order from its object side, a stop, a first lens (L1) having positive refracting power, a second lens (L2) having negative refracting power and a third lens (L3) 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). ?0.40<f/f3<0.15??(1-1) 0.30<hc7/hp7<2.0??(1-2) where f is the focal length of the whole wide-angle optical system, and f3 is the focal length of the third lens.

Abstract: A wide-angle optical system comprises, in order from its object side, a stop, a first lens (L1) having positive refracting power, a second lens (L2) having negative refracting power and a third lens (L3) 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). ?0.40<f/f3<0.15 ??(1-1) 0.30<hc7/hp7<2.0 ??(1-2) where f is the focal length of the whole wide-angle optical system, and f3 is the focal length of the third lens.