| 摘要 |
PROBLEM TO BE SOLVED: To obtain a photographing lens which has single-lens constitution, which is made small in size and where color aberration is excellently compensated by providing a positive lens with at least one aspherical surface and one diffraction lens surface and making it satisfy specified conditions. SOLUTION: As shown in the cross section of an optical axis in figure, this lens is constituted of an aperture diaphragm and the positive lens which is convex to an image surface and where the curvature of the lens surface on an image side is larger than that on an object side in order from the object side, and the positive lens is provided with at least one aspherical surface and at least one diffraction lens surface and constituted to satisfy the conditions shown by 0.30<|r<2>|/nf<0.50 and n>1.55. Provided that (n) is refractive index to the (d) line of the positive lens, r<2> is the paraxial radius of curvature of the lens surface on the image side of the positive lens, and (f) is a focal distance including the power of the diffraction lens surface of the positive lens. The diffraction lens surface is provided at least on either lens surface of the positive single lens.
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