| 摘要 |
This single-focus optical system is constituted from, in order from the enlarging side, a first lens group G1 and a second lens group G2 that has a positive refractive power. Each lens component is a singlet lens or a doublet lens. The first lens group G1 has a reducing-side negative lens component farthest to the reducing side, and the first lens group G1 has three or more negative lens components including said reducing-side negative lens component. The second lens group G2 is formed from, in order from the enlarging side, a first positive lens, a second positive lens, a first negative lens, and a third positive lens. All of the air spaces within the second lens group G2 are fixed during focusing or magnification changing. |
