Optical system, optical apparatus, and method of manufacturing optical system
An optical system (LS) includes lenses (L 22 ,L 23 ) satisfying the following conditional expressions, ndLZ +(0.01425× νdLZ )<2.12, and ν dLZ< 35.0, where ndLZ: a refractive index of the lens with reference to d-line, and νdLZ: Abbe number of the lens with reference to d-line.
1. An optical system comprising a glass lens satisfying the following conditional expressions:
ndLZ +(0.01425×ν dLZ )<2.12
ν dLZ< 35.0
1.83 <ndLZ +(0.00787 ×νdLZ )
0.702 <θgFLZ +(0.00316 ×νdLZ )<0.800
where
ndLZ: a refractive index of the lens with reference to d-line,
νdLZ: Abbe number of the lens with reference to d-line, and
θgFLZ: a partial dispersion ratio of the lens, which is defined by the following expression:
θ gFLZ =( ngLZ−nFLZ )/( nFLZ−nCLZ )
wherein a refractive index of the lens with reference to g-line is ngLZ, a refractive index of the lens with reference to F-line is nFLZ, and a refractive index of the lens with reference to C-line is nCLZ.
2. The optical system according to claim 1 , wherein the glass lens satisfies the following conditional expression:
18.0 <νdLZ <35.0.
3. The optical system according to any claim 1 , wherein the glass lens satisfies the following conditional expression:
1.55 <ndLZ.
4. The optical system according to claim 1 , wherein the glass lens satisfies the following conditional expression:
DLZ> 0.80
where
DLZ: a thickness [mm] of the lens on an optical axis.
5. The optical system according to claim 1 , wherein the glass lens satisfies the following conditional expressions:
ndLZ <1.63
ndLZ −(0.040 ×νdLZ −2.470)×ν dLZ <39.809.
6. The optical system according to claim 1 , wherein the glass lens satisfies the following conditional expression:
ndLZ −(0.020 ×νdLZ −1.080)×ν dLZ <16.260.
7. The optical system according to claim 1 , wherein the glass lens satisfies the following conditional expression:
18.0 <νdLZ <27.0.
8. The optical system according to claim 1 , wherein the glass lens satisfies the following conditional expression:
1.70 <ndLZ <1.85.
9. The optical system according to claim 1 , wherein the glass lens satisfies the following conditional expression:
1.55 <ndLZ <1.70.
10. The optical system according to claim 1 , wherein the glass lens satisfies the following conditional expression:
27.0 <νdLZ <35.0.
11. The optical system according to claim 10 , wherein the glass lens satisfies the following conditional expression:
1.55 <ndLZ <1.70.
12. The optical system according to claim 1 , wherein the glass lens satisfies the following conditional expression:
25.0 <νdLZ <31.0.
13. The optical system according to claim 12 , wherein the glass lens satisfies the following conditional expression:
1.55 <ndLZ <1.80.
14. The optical system according to claim 1 , comprising an object-side lens disposed nearest to an object,
wherein the glass lens is disposed nearer to an image than the object-side lens.
15. The optical system according to claim 1 , comprising an image-side lens disposed nearest to an image,
wherein the glass lens is disposed nearer to an object than the image-side lens.
16. An optical apparatus configured to comprise the optical system according to claim 1 .
17. The optical system according to claim 1 , wherein the glass lens is one of a cemented lens having two lenses cemented together.
18. The optical system according to claim 1 , wherein at least one of lens surfaces of the glass lens faces air.
19. The optical system according to claim 1 , including two glass lenses, each satisfying said conditional expressions and each being one of a respective cemented lens having two lenses cemented together.
20. A method of manufacturing an optical system, comprising:
disposing lenses within a lens barrel so as to include a lens satisfying the following conditional expressions:
ndLZ +(0.01425 ×νdLZ )<2.12
ν dLZ <35.0
1.83 <ndLZ +(0.00787 ×νdLZ )
0.702 <θgFLZ +(0.00316 ×νdLZ )<0.800
where
ndLZ: a refractive index of the lens with reference to d-line,
νdLZ: Abbe number of the lens with reference to d-line, and
θgFLZ: a partial dispersion ratio of the lens, which is defined by the following expression:
θ gFLZ =( ngLZ−nFLZ )/( nFLZ−nCLZ )
wherein a refractive index of the lens with reference to g-line is ngLZ, a refractive index of the lens with reference to F-line is nFLZ, and a refractive index of the lens with reference to C-line is nCLZ.