Patent ID: 8619375

Claim:
An image pickup lens comprising, in sequence from an object side to an image side: an aperture stop; a first lens having two convex surfaces and having a positive refractive power; a second lens in a meniscus shape whose convex surface faces to the object side having a negative refractive power; a third lens in a meniscus shape with the convex surface facing to the image side having a positive refractive power; a fourth lens in a meniscus shape with the convex surface facing to the object side having a negative refractive power; wherein the following conditions (1)Ëœ(5) are satisfied: 0.80 â‰¦f 1 /fâ‰¦ 1.05â€ƒâ€ƒ(1) âˆ’1.80 â‰¦f 2 /fâ‰¦âˆ’ 1.20â€ƒâ€ƒ(2) âˆ’0.70 â‰¦R 1 /R 2â‰¦âˆ’0.17â€ƒâ€ƒ(3) 4.00 â‰¦R 3 /R 4â‰¦70.00â€ƒâ€ƒ(4) 0.10 â‰¦d 4 /fâ‰¦ 0.20â€ƒâ€ƒ(5) where f is the focal length of the entire lens; f 1 is the focal length of the first lens; f 2 is the focal length of the second lens; R 1 is the curvature radius of the object side surface of the first lens; R 2 is the curvature radius of the image side surface of the first lens; R 3 is the curvature radius of the object side surface of the second lens; R 4 is the curvature radius of the image side surface of the second lens; d 4 is the distance along the optical axis between the image side of the second lens and the object side of the third lens.