| 摘要 |
PROBLEM TO BE SOLVED: To provide a wide-angle lens small in size, light in weight, capable of being produced at low cost and having a long exit pupil. SOLUTION: This lens is provided with a 1st lens, a 2nd lens and a 3rd lens arranged in order from an object side, and a diaphragm arranged between the 2nd and the 3rd lenses. The 1st lens is a concave aspherical lens and the 2nd and the 3rd lenses are convex aspherical lenses. When the respective focal distances of the 1st to the 3rd lenses are defined as f1, f2 and f3, the Abbe numbers thereof are defined asνd1,νd2 andνd3, and the synthetic focal distance of the 2nd and the 3rd lenses is defined as f23, they satisfy following conditional expressions (1) to (3). (1) 0.5<f2/f3<3.0 (2)νd3/νd2>1.5 (3) 0.5<|f1/f2|<3.0.
|
