Optical system, optical apparatus, and method of manufacturing optical system
An optical system comprises a first lens group having positive refractive power, a second lens group having positive refractive power, and a third lens group having negative refractive power, arranged in order from an object side, wherein, when focusing, the second lens group moves along an optical axis, and the optical system satisfies the conditional expressions 0.100<BFa/f<0.500 and −5.000<(−G1R1)/f<500.000, where BFa is an air equivalent distance on the optical axis between a lens surface on an image side of a lens disposed closest to an image and the image, f is a focal length of the optical system, and G1R1 is a radius of curvature of a lens surface on the object side for a lens component disposed farthest on the object side in the first lens group.
1. An optical system comprising:
a first lens group having positive refractive power, a second lens group having positive refractive power, and a third lens group having negative refractive power, arranged in order from an object side, wherein
when focusing, the second lens group moves along an optical axis,
the first lens group is stationary when focusing, and
the optical system satisfies the following conditional expressions:
0.100< BFa/f< 0.350
0.25< fF/fR< 3.00
0.50< FNO ×( f 1/ f )<3.20 and
1.000<(− G 1 R 1)/ f 1<50.000
where BFa is an air equivalent distance on the optical axis between a lens surface on an image side of a lens disposed closest to an image and the image,
f is a focal length of the optical system,
fF is a composite focal length of lenses disposed farther on the object side than a diaphragm in the optical system,
fR is a composite focal length of lenses disposed farther on the image side than the diaphragm in the optical system at a state of focusing on infinity,
FNO is an F-number of the optical system,
f1 is a focal length of the first lens group, and
G1R1 is a radius of curvature of a lens surface on the object side of a lens component disposed closest to the object in the first lens group.
2. The optical system according to claim 1 , wherein the optical system satisfies the following conditional expression
1.000<(− G 1 R 1)/ f 1<5.000.
3. The optical system according to claim 1 , wherein the first lens group comprises a diaphragm.
4. The optical system according to claim 1 , wherein the optical system satisfies the following conditional expression
0.010< f/f 1<5.000.
5. The optical system according to claim 1 , wherein the optical system satisfies the following conditional expression
0.010< f/f 2<5.000
where f2 is a focal length of the second lens group.
6. The optical system according to claim 1 , wherein the optical system satisfies the following conditional expression
0.010< f 1/ f 2<5.000
where
f2 is a focal length of the second lens group.
7. The optical system according to claim 1 , wherein the optical system satisfies the following conditional expression
0.010< f 1/(− f 3)<3.000
where
f3 is a focal length of the third lens group.
8. The optical system according to claim 1 , wherein the optical system satisfies the following conditional expression
−10.0<( G 1 R 2+ G 1 R 1)/( G 1 R 2− G 1 R 1)<10.0
where
G1R2 is a radius of curvature of a lens surface on the image side for a lens component disposed farthest on the object side in the first lens group.
9. The optical system according to claim 1 , wherein the optical system satisfies the following conditional expression
0.30<{1−(β2) 2 }×(β3) 2 <2.00
where β2 is a lateral magnification of the second lens group for a state of focusing on infinity, and
β3 is a lateral magnification of the third lens group.
10. The optical system according to claim 1 , wherein the optical system satisfies the following conditional expression
15.0°<2ω<85.00
where 2ω is an angle of view of the optical system.
11. An optical apparatus comprising a lens barrel including the optical system according to claim 1 .
12. A method of manufacturing an optical system including a first lens group having positive refractive power, a second lens group having positive refractive power, and a third lens group having negative refractive power, arranged in order from an object side, the method comprising:
disposing each lens within a lens barrel such that
when focusing, the second lens group moves along an optical axis,
the first lens group is stationary when focusing, and
the optical system satisfies set A or set B of conditional expressions,
wherein set A comprises:
0.100< BFa/f< 0.350
0.25< fF/fR< 3.00
0.50< FNO ×( f 1/ f )<3.20 and
1.000<(− G 1 R 1)/ f 1<50.000
where BFa is an air equivalent distance on the optical axis between a lens surface on an image side of a lens disposed closest to an image and the image,
f is a focal length of the optical system,
fF is a composite focal length of lenses disposed farther on the object side than a diaphragm in the optical system,
fR is a composite focal length of lenses disposed farther on the image side than the diaphragm in the optical system at a state of focusing on infinity,
FNO is an F-number of the optical system,
f1 is a focal length of the first lens group, and
G1R1 is a radius of curvature of a lens surface on the object side of a lens component disposed closest to the object in the first lens group, and
wherein set B comprises:
0.100< BFa/f≤ 0.249
0.50< FNO ×( f 1/ f )<3.00 and
20.0°<2ω<85.0°
where 2ω is an angle of view of the optical system.
13. An optical system comprising:
a first lens group having positive refractive power, a second lens group having positive refractive power, and a third lens group having negative refractive power, arranged in order from an object side, wherein
when focusing, the second lens group moves along an optical axis,
the first lens group is stationary when focusing, and
the optical system satisfies the following conditional expressions:
0.100< BFa/f≤ 0.249 and
0.50< FNO ×( f 1/ f )<3.00 and
20.0°<2ω<85.0°
where BFa is an air equivalent distance on the optical axis between a lens surface on an image side of a lens disposed closest to an image and the image,
f is a focal length of the optical system,
FNO is an F-number of the optical system,
f1 is a focal length of the first lens group, and
2ω is an angle of view of the optical system.