| 摘要 |
PROBLEM TO BE SOLVED: To obtain a photographic lens system which is composed of four lenses as a whole and has a high telecentric property and a high optical performance. SOLUTION: This photographic lens system is composed of a first group, consisting of a meniscus lens having the concave directed to the image side, a second group consisting of a cemented lens where a negative lens having concaves as both lens faces and a positive lens are joined, and a third group consisting of a positive lens in order from the object side, and an aperture stop is provided between the first and second groups, an a focal length f of the entire system, a focal length f1 of the first group, a refraction powerϕ2a of the lens face on the object side of the second group, and a refraction powerϕ3 of the third group are set properly.
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