Wide-angle lens and imaging device

Abstract

An imaging lens is formed from a first group lens having negative power, a second group lens having positive power, a third group lens having negative power, and a fourth group lens having positive power, disposed in order from the subject side to the image side. Letting f be the focal distance for the entire lens system and ff2 the focal distance for the second group lens, 1.0≤ff2/f≤2.0 is satisfied; therefore, the entire length of the lens system can be kept short and image curvature can be suppressed. In addition, each of the subject side lens surfaces and the image side lens surfaces for the second group lens, third group lens, and fourth group lens are provided with aspherical surface shapes; therefore, the imaging lens is constituted to be bright.

1 . A wide-angle lens consisting of:
 a first lens having negative power and a concave shape on the image side,   a second lens having positive power,   a third lens having positive power and a convex shape on the image side,   a fourth lens is a meniscus lens having negative power and a concave shape on the object side, and   a fifth lens having positive power,   arranged in order from an object side toward an image side.   
     
     
         2 . The wide-angle lens according to  claim 1 , wherein
 the second lens and the third lens are provided with a lens having an Abbe number of 40 or greater, and   the fourth lens is provided with a lens having an Abbe number of 35 or less.   
     
     
         3 . The wide-angle lens according to  claim 1 , wherein the following conditional expression is satisfied,
   −1.9≤ ff 2/ ff 3≤−1.3.
   Wherein ff2 is the composite focal length of the second lens and the third lens, and ff3 is the focal length of the fourth lens.