| 摘要 |
PROBLEM TO BE SOLVED: To provide a rear attachment lens which is attached to a main lens system at an image side thereof, is reduced in the fluctuations of various aberrations when the focal length of an entire system is long, especially in the fluctuations of chromatic aberrations and can maintain high optical performance as the entire system. SOLUTION: The rear attachment lens detachably attached to the main lens system at the image side thereof to lengthen the focal length as compared with the focal length of an independent main lens system includes a negative lens Gn1 disposed such that, when L is a distance between a lens surface closest to an object side and a lens surface closest to the image side in the rear attachment lens, the negative lens is within an area in which a distance from the lens surface closest to the object side in the rear attachment lens to the negative lens is in the range of 0.5L to 1.0L. Whenνdn1 is an Abbe number of a material of the negative lens Gn1 with respect to the d-line andθgFn1 is a partial dispersion ratio of the material of the negative lens Gn1 with respect to the g-line and the F-line, the following conditions are satisfied: 10<νdn1<23, 0.020<θgFn1-0.6438+0.001682×νdn1<0.100. COPYRIGHT: (C)2011,JPO&INPIT |
