Optical system, optical apparatus and method for manufacturing the optical system
An optical system (OL) used for an optical apparatus such as a camera ( 1 ) includes a focusing group (Gf) that moves upon focusing, a diffractive optical element (GD) disposed on an object side of the focusing group (Gf) and a negative lens element (L1 n ) disposed on the object side of the diffractive optical element (GD). The optical system (OL) satisfies the following expressions 0.030< f/fpf <0.050 nd 1 n +0.006×ν d 1 n <1.910 35<ν d 1 n where, f: focal length of whole system in infinity focusing state fpf: focal length of diffractive optical element (GD) nd1 n : refractive index of medium of negative lens element (L1 n ) on d-line νd1 n : Abbe number of medium of negative lens element (L1 n ) on d-line.
1. An optical system comprising:
a focusing group that moves upon focusing;
a diffractive optical element disposed on an object side of the focusing group; and
a negative lens element disposed on the object side of the diffractive optical element, wherein
the following expressions are satisfied:
0.030< f/fpf< 0.050
nd 1 n+ 0.006×ν d 1 n< 1.890
35<ν d 1 n
where,
f: focal length of whole system in infinity focusing state
fpf: focal length of the diffractive optical element
nd1n: refractive index of medium of the negative lens element on d-line
νd1n: Abbe number of medium of the negative lens element on d-line
where, the lens element refers to each lens constituting a single lens or cemented lens.
2. The optical system according to claim 1 , wherein the following expression is satisfied:
TL/ f< 0.61
where,
TL: total length in infinity focusing state
f: focal length of whole system in infinity focusing state.
3. The optical system according to claim 1 , comprising:
a first lens group having positive refractive power;
a second lens group which is the focusing group and has negative refractive power;
a third lens group, which are disposed in order from an object.
4. The optical system according to claim 3 , wherein the first lens group comprises two positive lens elements and the negative lens element on the object side of the diffractive optical element.
5. The optical system according to claim 3 , wherein the following expression is satisfied:
0.200< f 1/ f< 0.500
where,
f1: focal length of the first lens group
f: focal length of whole system.
6. An optical system comprising:
a focusing group that moves upon focusing and has at least two lens elements;
a diffractive optical element disposed on an object side of the focusing group;
a vibration-isolating group disposed on an image side of the focusing group and configured to move so as to have a displacement component in a direction orthogonal to an optical axis; and
at least three negative lens elements disposed on the image side of the vibration-isolating group,
at least two of the three negative lens elements are specific negative lens elements that satisfy the following expressions:
0.654<θ gF 3 n+ 0.00168×ν d 3 n
1.98< nd 3 n+ 0.01×ν d 3 n
where,
θgF3n: partial dispersion ratio of medium of the specific negative lens element
νd3n: Abbe number of medium of the specific negative lens element on d-line
nd3n: refractive index of medium of the specific negative lens element on d-line,
the optical system further satisfying the following expression:
TL/ f< 0.61
where,
TL: total length in infinity focusing state
f: focal length of whole system in infinity focusing state
where, the lens element refers to each lens constituting a single lens or cemented lens.
7. The optical system according to claim 6 , wherein at least one of the specific negative lens elements satisfies the following expression:
70<ν d 3 n 1
where,
νd3n1: Abbe number of medium of the specific negative lens element on d-line.
8. The optical system according to claim 6 , wherein at least one of the specific negative lens elements satisfies the following expression:
ν d 3 n 2<34
where,
νd3n2: Abbe number of medium of the specific negative lens element on d-line.
9. The optical system according to claim 6 , comprising at least one of specific positive lens elements on the image side of the vibration-isolating group that satisfies the following expressions:
θ gF 3 p+ 0.00168×ν d 3 p 1<0.664
ν d 3 p 1<70
where,
θgF3p: partial dispersion ratio of medium of the specific positive lens element
νd3p1: Abbe number of medium of the specific positive lens element on d-line.
10. The optical system according to claim 6 , further comprising a first cemented lens, a second cemented lens and a third cemented lens on the image side of the vibration-isolating group, which are disposed in order from the object, wherein
the following expressions are satisfied:
−1.20< f 3 c 1/ f 3 c 2<−0.80
0.30< f 3 c 1/ f 3 c 3<0.50
where,
f3c1: focal length of the first cemented lens
f3c2: focal length of the second cemented lens
f3c3: focal length of the third cemented lens.
11. The optical system according to claim 10 , wherein at least one of the cemented lenses disposed on the image side of the vibration-isolating group satisfies the following expressions:
ν d 3 p−νd 3 n< 10
0.10< nd 3 n−nd 3 p
where,
νd3p: Abbe number of medium of positive lens element constituting the cemented lens on d-line
νd3n: Abbe number of medium of negative lens elements constituting the cemented lens on d-line
nd3p: refractive index of medium of positive lens elements constituting the cemented lens on d-line
nd3n: refractive index of medium of negative lens elements constituting the cemented lens on d-line.
12. The optical system according to claim 6 , comprising:
a first lens group having positive refractive power;
a second lens group which is the focusing group and has negative refractive power; and
a third lens group, which are disposed in order from the object.
13. The optical system according to claim 12 , wherein the second lens group which is the focusing group comprises a positive lens element that satisfies the following expression:
ν d 2 p< 50
where,
νd2p: Abbe number of medium of the positive lens element included in the second lens group on d-line.
14. An optical apparatus comprising the optical system according to claim 1 .
15. An optical apparatus comprising the optical system according to claim 6 .
16. An optical system comprising:
a focusing group that moves upon focusing;
a diffractive optical element disposed on an object side of the focusing group; and
a negative lens element disposed on the object side of the diffractive optical element, wherein
all lenses disposed on the object side of the diffractive optical element are positive lens elements except the negative lens element, and
the following expressions are satisfied:
0.030< f/fpf< 0.050
nd 1 n+ 0.006×ν d 1 n< 1.910
35<ν d 1 n
where,
f: focal length of whole system in infinity focusing state
fpf: focal length of the diffractive optical element
nd1n: refractive index of medium of the negative lens element on d-line
νd1n: Abbe number of medium of the negative lens element on d-line
where, the lens element refers to each lens constituting a single lens or cemented lens.
17. An optical system comprising:
a focusing group that moves upon focusing;
a diffractive optical element disposed on an object side of the focusing group; and
a negative lens element disposed on the object side of the diffractive optical element, wherein
the following expressions are satisfied:
0.030< f/fpf< 0.050
nd 1 n+ 0.006×ν d 1 n< 1.910
35<ν d 1 n
θ gF 1 n+ 0.00168×ν d 1 n< 0.643
where,
f: focal length of whole system in infinity focusing state
fpf: focal length of the diffractive optical element
nd1n: refractive index of medium of the negative lens element on d-line
νd1n: Abbe number of medium of the negative lens element on d-line
θgF1n: partial dispersion ratio of medium of the negative lens element
where, the lens element refers to each lens constituting a single lens or cemented lens.
18. An optical system comprising:
a focusing group that moves upon focusing;
a diffractive optical element disposed on an object side of the focusing group; and
a negative lens element disposed on the object side of the diffractive optical element, wherein
the optical system comprises a first lens group having positive refractive power, a second lens group which is the focusing group, and a third lens group, which are disposed in order from an object,
the first lens group comprises one positive lens element and one negative lens element, which are disposed on the image side of the diffractive optical element, and
the following expressions are satisfied:
0.030< f/fpf< 0.050
nd 1 n+ 0.006×ν d 1 n< 1.910
35<ν d 1 n
where,
f: focal length of whole system in infinity focusing state
fpf: focal length of the diffractive optical element
nd1n: refractive index of medium of the negative lens element on d-line
νd1n: Abbe number of medium of the negative lens element on d-line
where, the lens element refers to each lens constituting a single lens or cemented lens.
19. An optical system comprising:
a focusing group that moves upon focusing;
a diffractive optical element disposed on an object side of the focusing group; and
a negative lens element disposed on the object side of the diffractive optical element, wherein
the optical system comprises a first lens group having positive refractive power, a second lens group which is the focusing group, and a third lens group, which are disposed in order from an object, and
the following expressions are satisfied:
0.030< f/fpf< 0.050
nd 1 n+ 0.006×ν d 1 n< 1.910
35<ν d 1 n
0.001< f 1/ fpf< 0.030
where,
f: focal length of whole system in infinity focusing state
f1: focal length of the first lens group
fpf: focal length of the diffractive optical element
nd1n: refractive index of medium of the negative lens element on d-line
νd1n: Abbe number of medium of the negative lens element on d-line
where, the lens element refers to each lens constituting a single lens or cemented lens.
20. A method for manufacturing an optical system comprising a focusing group that moves upon focusing, and a diffractive optical element disposed on an object side of the focusing group,
the method comprising one of the following features A, B, C, D, E and F, wherein
the feature A comprising:
disposing a negative lens element on the object side of the diffractive optical element; and
disposing the lens groups and lens elements in a lens barrel so as to satisfy the following expressions:
0.030< f/fpf< 0.050
nd 1 n+ 0.006×ν d 1 n< 1.890
35<ν d 1 n
where,
f: focal length of whole system in infinity focusing state
fpf: focal length of the diffractive optical element
nd1n: refractive index of medium of the negative lens element on d-line
νd1n: Abbe number of medium of the negative lens element on d-line
where, the lens element refers to each lens constituting a single lens or cemented lens,
the feature B comprising:
disposing the focusing group having at least two lens elements;
disposing a vibration-isolating group on an image side of the focusing group and configured to move so as to have a displacement component in a direction orthogonal to an optical axis;
disposing at least three negative lens elements on the image side of the vibration-isolating group; and
disposing the lens groups and lens elements in a lens barrel so that at least two of the three negative lens elements being specific negative lens elements that satisfy the following expressions:
0.654<θ gF 3 n+ 0.00168×ν d 3 n
1.98< nd 3 n+ 0.01×ν d 3 n
where,
θgF3n: partial dispersion ratio of medium of the specific negative lens element
νd3n: Abbe number of medium of the specific negative lens element on d-line
nd3n: refractive index of medium of the specific negative lens element on d-line; and
the method further comprising disposing the lens groups and lens elements so as to satisfy the following expression:
TL/ f< 0.61
where,
TL: total length in infinity focusing state
f: focal length of whole system in infinity focusing state
where, the lens element refers to each lens constituting a single lens or cemented lens,
the feature C comprising:
disposing a negative lens element on the object side of the diffractive optical element;
arranging all lenses disposed on the object side of the diffractive optical element so as to be consisted of positive lens elements except the negative lens element; and
disposing the lens groups and lens elements in a lens barrel so as to satisfy the following expressions:
0.030< f/fpf< 0.050
nd 1 n+ 0.006×ν d 1 n< 1.910
35<ν d 1 n
where,
f: focal length of whole system in infinity focusing state
fpf: focal length of the diffractive optical element
nd1n: refractive index of medium of the negative lens element on d-line
νd1n: Abbe number of medium of the negative lens element on d-line
where, the lens element refers to each lens constituting a single lens or cemented lens,
the feature D comprising:
disposing a negative lens element on the object side of the diffractive optical element; and
disposing the lens groups and lens elements in a lens barrel so as to satisfy the following expressions:
0.030< f/fpf< 0.050
nd 1 n+ 0.006×ν d 1 n< 1.910
35<ν d 1 n
θ gF 1 n+ 0.00168×ν d 1 n< 0.643
where,
f: focal length of whole system in infinity focusing state
fpf: focal length of the diffractive optical element
nd1n: refractive index of medium of the negative lens element on d-line
νd1n: Abbe number of medium of the negative lens element on d-line
θgF1n: partial dispersion ratio of medium of the negative lens element
νd1n: Abbe number of medium of the negative lens element on d-line
where, the lens element refers to each lens constituting a single lens or cemented lens,
the feature E comprising:
disposing a negative lens element on the object side of the diffractive optical element;
disposing a first lens group having positive refractive power, a second lens group which is the focusing group, and a third lens group, in order from an object;
disposing the first lens group comprising one positive lens element and one negative lens element on the image side of the diffractive optical element; and
disposing the lens groups and lens elements in a lens barrel so as to satisfy the following expressions:
0.030< f/fpf< 0.050
nd 1 n+ 0.006×ν d 1 n< 1.910
35<ν d 1 n
where,
f: focal length of whole system in infinity focusing state
fpf: focal length of the diffractive optical element
nd1n: refractive index of medium of the negative lens element on d-line
νd1n: Abbe number of medium of the negative lens element on d-line
where, the lens element refers to each lens constituting a single lens or cemented lens,
the feature F comprising:
disposing a negative lens element on the object side of the diffractive optical element;
disposing the optical system comprising a first lens group having positive refractive power, a second lens group which is the focusing group, and a third lens group, in order from an object; and
disposing the lens groups and lens elements in a lens barrel so as to satisfy the following expressions:
0.030< f/fpf< 0.050
nd 1 n+ 0.006×ν d 1 n< 1.910
35<ν d 1 n
0.001< f 1/ fpf< 0.030
where,
f: focal length of whole system in infinity focusing state
f1: focal length of the first lens group
fpf: focal length of the diffractive optical element
nd1n: refractive index of medium of the negative lens element on d-line
νd1n: Abbe number of medium of the negative lens element on d-line
where, the lens element refers to each lens constituting a single lens or cemented lens.