| 摘要 |
PROBLEM TO BE SOLVED: To provide a small-sized lightweight optical system capable of correcting excellently various aberrations including chromatic aberration, and to provide an optical apparatus having the optical system. SOLUTION: The optical system includes in due order from the object side to the image side, a front group having positive refractive power, a lens stop, and a rear group having positive or negative refractive power. The front group has a positive lens Gp1 and the rear group has a negative lens Gn1. When an Abbe number of a material of the positive lens Gp1, and a partial dispersion ratio for a g-line and an F-line are defined asνdp1 andθgFp1 respectively, and a refractive index and an Abbe number for a d-line of a material of the negative lens Gn1, and a partial dispersion ratio for the g-line and the F-line are defined as Ndn1,νdn1 andθgFn1 respectively, the following conditions are satisfied: 75<νdp1<99, 0.020<θgFp1-0.6438+0.001682×νdp1<0.100, 1.75<Ndn1<2.10, and 0.020<θgFn1-0.6438+0.001682×νdn1<0.100. COPYRIGHT: (C)2011,JPO&INPIT |
