| 摘要 |
PROBLEM TO BE SOLVED: To obtain the lens for the small-sized solid image pickup element which consists of a small number of lens elements and is a wide-angle system by arranging a low-pass filter between the front and rear groups. SOLUTION: This lens consists of the front group which has negative refracting power and the rear group which has positive refracting power in order from an object side. The rear-side principal point of the front group is closer to the image side than the object-side vertex of the front group. The low-pass filter Lo and an infrared-ray cutting filter Fi are arranged between the front group and rear group. The front group consists preferably of a biconcave lens or meniscus lens which is convex to the object side and the rear group consists of a single lens with positive refracting power and a cemented lens. Here, d12 >=2.0mm and|d12 /f1|<=1.8 hold preferably, where d12 is the air gap between the front and rear groups and f1 is the focal length of the front group.
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