Patent ID: 6775074
Filing Date: 2004-08-10
Classification: G02B

Abstract:
An image pickup lens, which comprises, in order from an object side thereof, a first lens element having negative refracting power, a second lens element having positive refracting power, a stop, a third lens element having negative refracting power and a fourth lens element having positive refracting power, wherein lens elements having refracting power due to refraction are defined only by said first to fourth lens elements and the following conditions (1) and (2) are satisfied:50>&ngr;d1âˆ’&ngr;d2>10â€ƒâ€ƒ(1) 2>f/f3>0.35â€ƒâ€ƒ(2) where &ngr;d1 is a d-line reference Abbe number of the first lens element, &ngr;d2 is a d-line reference Abbe number of the second lens element, f is a focal length of the image pickup lens, and f3 is a composite focal length of the third and fourth lens elements.