| 摘要 |
PROBLEM TO BE SOLVED: To provide an image forming optical system which excellently corrects a color aberration over the entire screen and has a high optical performance, and an optical instrument including it.SOLUTION: One or more positive lenses are provided in a lens group more on a reduction conjugate side than an aperture diaphragm surface, and a partial dispersion ratio and an Abbe number of at least one of the positive lenses are set such that a refractive index, the position and power, etc., satisfy an appropriate relation. |
