| 摘要 |
PROBLEM TO BE SOLVED: To provide a lens where a half field angle and a back focus can be set sufficiently large, and can be miniaturized. SOLUTION: This lens is provided with a 1st lens L1 being a negative meniscus lens whose convex surface is opposed to an object side, a 2nd lens L2 being a positive lens whose convex surface is faced to an image side, a 3rd lens L3 being the positive lens, a 4th lens L4 being a biconcave negative lens, a 5th lens L5 being the positive lens and a 6th lens L6 being the positive lens in this order from the object side. In such a case, following conditional expressions are satisfied. 0.55<|f1 /f2|<0.9 and 0.45<f/f3 <0.8; provided that f1 is the focal distance of the 1st lens L1 , f2 is the focal distance of the 2nd lens L2 , f3 is the focal distance of the 3rd lens L3 , and (f) is the focal distance of an entire system.
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