Optical system and optical apparatus
An optical system consists essentially of, in order from the magnification side, a first lens having a positive refractive power with a convex surface on the magnification side, a second lens having a negative refractive power, a third lens having a negative refractive power, a fourth lens having a positive refractive power, a fifth lens having a positive refractive power, and a sixth lens having a positive refractive power, wherein the following conditional expressions (1) and (2) are satisfied: 0.17< D 2/ f <0.80 (1) −60<ν d 1−ν d 2<−15 (2) where D2: distance on the optical axis between the first lens and the second lens f: focal length of the entire system νd1: Abbe number of the first lens with reference to d-line νd2: Abbe number of the second lens with reference to d-line.
1. An optical system, consisting of, in order from the magnification side, a first lens having a positive refractive power with a convex surface on the magnification side, a second lens having a negative refractive power, a third lens having a negative refractive power, a fourth lens having a positive refractive power, a fifth lens having a positive refractive power, and a sixth lens having a positive refractive power, wherein the following conditional expressions (1) and (2) are satisfied:
0.17< D 2/ f< 0.80 (1)
−60<ν d 1−ν d 2<−15 (2)
where
D2: distance on the optical axis between the first lens and the second lens
f: focal length of the entire system
νd1: Abbe number of the first lens with reference to d-line
νd2: Abbe number of the second lens with reference to d-line.
2. The optical system of claim 1 , wherein the following conditional expression (3) is satisfied:
0.25< f/f 1<0.70 (3)
where
f1: focal length of the first lens.
3. The optical system of claim 1 , wherein the magnification side surface of the third lens is a concave surface.
4. The optical system of claim 1 , wherein the second lens is a meniscus lens with a concave surface on the reduction side.
5. The optical system of claim 1 , wherein the reduction side surface of the fourth lens is a convex surface.
6. The optical system of claim 1 , wherein the reduction side surface of the fifth lens is a convex surface.
7. The optical system of claim 1 , wherein the fifth lens is a biconvex lens.
8. The optical system of claim 1 , wherein the magnification side surface of the sixth lens is a convex surface.
9. The optical system of claim 1 , wherein the following conditional expression (1-1) is satisfied:
0.20< D 2/ f< 0.55 (1-1).
10. The optical system of claim 1 , wherein the following conditional expression (2-1) is satisfied:
−50<ν d 1−ν d 2<−18 (2-1)
where
νd1: Abbe number of the first lens with reference to d-line
νd2: Abbe number of the second lens with reference to d-line.
11. The optical system of claim 1 , wherein the following conditional expression (3-1) is satisfied:
0.30< f/f 1<0.60 (3-1)
where
f1: focal length of the first lens.
12. An optical apparatus provided with the optical system of claim 1 .
13. An optical system, consisting of, in order from the magnification side, a first lens having a positive refractive power with a convex surface on the magnification side, a second lens having a negative refractive power, a third lens having a negative refractive power, a fourth lens having a positive refractive power, a fifth lens having a positive refractive power, and a sixth lens having a positive refractive power, wherein the following conditional expressions (1) and (3) are satisfied:
0.17< D 2/ f< 0.80 (1)
0.25< f/f 1<0.70 (3)
where
D2: distance on the optical axis between the first lens and the second lens
f: focal length of the entire system
f1: focal length of the first lens.
14. The optical system of claim 13 , wherein the following conditional expression (1-1) is satisfied:
0.20< D 2/ f< 0.55 (1-1).
15. The optical system of claim 13 , wherein the following conditional expression (3-1) is satisfied:
0.30< f/f 1<0.60 (3-1).
16. An optical apparatus provided with the optical system of claim 13 .