Patent attributes
A photography lens 6 includes: an aperture stop 4; a first lens 1 having positive refractive power, and at least one of the lens surfaces is aspherical; a second lens 2 having negative refractive power, and at least one of the lens surfaces is aspherical; and a third lens 3 having positive refractive power, and both lens surfaces are aspherical, arranged in that order from an object side to an image surface side. When f indicates the focal length of the entire optical system, f1 indicates the focal length of the first lens 1, f2 indicates the focal length of the second lens 2, r21 indicates the radius of curvature of the lens surface of the second lens 2 facing the object side, and n2 indicates the refractive index of the second lens 2, the following conditional expressions (1) to (3) are satisfied:0.8<f1/f<0.9 (1)−1.0<f2/f<0.7 (2)−1.0<r21/((n2−1)·f)<−0.7. (3)Thus, it is possible to provide a bright photography lens having high performance and an F number of 3.5 or less. The photography lens can be small and thin, and it can be manufactured at low cost, and it is compatible with a high pixel imaging element of a megapixel or more incorporated in a small mobile product such as a mobile phone.
