| 摘要 |
PROBLEM TO BE SOLVED: To shorten the focal distance of an image pickup lens, also to secure the back focus distance thereof and to easily produce the lens. SOLUTION: This lens is constituted of a 1st lens 1 consisting of a concave lens whose mark for the center radius of curvature is not the same and a 2nd lens 2 consisting of a convex lens. At least the 1st surface of the 1st lens 1 is formed to be aspherical shape and the focal distance of an entire lens system is set within a range from the back focus distance×0.67 to the back focus distance×1.45 and the focal distance of the 2nd lens 2 is set within a range from the focal distance of the 1st lens 1×0.25 to the focal distance of the 1st lens 1×0.8.
|
