| 摘要 |
PROBLEM TO BE SOLVED: To excellently correct various types of aberration by using a diffraction surface. SOLUTION: This lens is a rear attachment lens attached to the image surface side of a principal lens M being a photographing optical system and capable of extending the focal distance of the lens M to a long-focus distance side. It has a diffraction surface D consisting of a diffraction grating having rotationally symmetric shape with respect to the optical axis and having negative refractive power to diffracted light of designed diffraction order. When the height of on-axis paraxial ray, made incident on the diffraction surface having the negative refractive power, from the optical axis is called hD, and the height of a pupil paraxial ray, made incident on the diffraction surface having the negative refractive power, from the optical axis is called HD, the lens satisfies a conditional expression|hDHD|>hD<2> .
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