| 摘要 |
PROBLEM TO BE SOLVED: To provide a close-up lens capable of photographing an object at a close distance of <40 cm when the close-up lens is used together with a semi-wide angle lens. SOLUTION: The close-up lens 20 is constituted of a 1st lens group 21 constituted of one negative lens, and a 2nd lens group 22 constituted of one positive lens. Provided that the focal distance of the 1st lens group 21 is expressed by (f1), the focal distance of the 2nd lens group 22 is expressed by (f2), the synthetic focal distance of the whole close up lens 20 is expressed by (f), the photographing magnification of the whole optical system including a photographing lens 10 is expressed by (β), the diagonal length of an exposure screen by the whole optical system including the photographing lens 10 is expressed by (d), a distance from the lens surface positioned closest to the image side of the 2nd lens group 22 to the incident pupil position of the photographing lens 10 is expressed by (Re), the following conditional expressions are satisfied; -2.0<=f1/f2<=-0.5, d/3f<=β<=d/f and 5<=Re<=30.
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