US 12,724,248 B2 · Large aperture ratio telephoto zoom lens

Abstract

Disclosed is a large aperture ratio telephoto zoom lens with high optical performance, equipped with a vibration reduction system and a silent and speedy focusing mechanism and yet small and lightweight. The large aperture ratio telephoto zoom lens includes, sequentially from the object side to the image side: a first lens group G1 with positive refractive power, fixed relative to the image surface during zooming; a second lens group G2 with negative refractive power; a third lens group G3 with negative refractive power; a fourth lens group G4 with positive refractive power; an aperture diaphragm S; and a subsequent lens group GR composed of a plurality of lens groups. Distances between adjacent lens groups change during zooming from the wide-angle end to the telephoto end. The subsequent lens group GR includes a focusing lens group that moves during focusing from an infinite distance object to a close distance object.

Claims13

Dependent claims

A large aperture ratio telephoto zoom lens comprising, sequentially from an object side to an image side:

a first lens group G1 with positive refractive power, fixed relative to an image surface during zooming;
a second lens group G2 with negative refractive power;
a third lens G3 group with negative refractive power;
a fourth lens group G4 with positive refractive power;
an aperture diaphragm S;
and a subsequent lens group GR composed of a plurality of lens groups,
distances between adjacent lens groups changing during zooming from a wide-angle end to a telephoto end,
the subsequent lens group GR including a focusing lens group that moves during focusing from an infinite distance object to a close distance object,
the large aperture ratio telephoto zoom lens satisfying following conditional expressions:
-
1.18
<
f
⁢
2
/
fT
<
-
0
.37
(
1
)
-
0.94
<
f
⁢
3
/
fT
<
-
0
.
3
⁢
5
,
where
(
2
)
f2 represents a focal length of the second lens group G2,
fT represents a focal length of entire optical system at the telephoto end when focusing on infinity, and
f3 represents a focal length of the third lens group G3.

44 more elements

A large aperture ratio telephoto zoom lens comprising, sequentially from an object side to an image side:

a first lens group G1 with positive refractive power, fixed relative to an image surface during zooming;
a second lens group G2 with negative refractive power;
a third lens group G3 with negative refractive power;
a fourth lens group G4 with positive refractive power;
an aperture diaphragm S that is fixed relative to the image surface during zooming;
a fifth lens group G5 with positive refractive power, fixed relative to the image surface during zooming;
a sixth lens group G6 with negative refractive power;
a seventh lens group G7 with positive refractive power;
and an eighth lens group G8 with fixed negative refractive power relative to the image surface during zooming,
distances between adjacent lens groups changing during zooming from a wide-angle end to a telephoto end,
the large aperture ratio telephoto zoom lens comprising a focusing lens group that moves during focusing from an infinite distance object to a close distance object closer to the image side than the aperture diaphragm S,
the large aperture ratio telephoto zoom lens satisfying following conditional expressions:
-
1.18
<
f
⁢
2
/
fT
<
-
0
.37
(
1
)
-
0.94
<
f
⁢
3
/
fT
<
-
0
.
3
⁢
5
,
where
(
2
)
f2 represents a focal length of the second lens group G2,
fT represents a focal length of the entire optical system at the telephoto end when focusing on infinity, and
f3 represents a focal length of the third lens group G3.

47 more elements

A large aperture ratio telephoto zoom lens comprising, sequentially from an object side to an image side:

a first lens group G1 with positive refractive power, fixed relative to an image surface during zooming;
a second lens group G2 with negative refractive power;
a third lens group G3 with negative refractive power;
a fourth lens group G4 with positive refractive power;
an aperture diaphragm S that is fixed relative to the image surface during zooming;
a fifth lens group G5 with positive refractive power, fixed relative to the image surface during zooming;
a sixth lens group G6 with negative refractive power;
a seventh lens group G7 with positive refractive power;
and an eighth lens group G8 with fixed negative refractive power relative to the image surface during zooming,
the sixth lens group G6 comprising a single positive lens and a single negative lens sequentially from the object side to the image side, the seventh lens group G7 comprising a single positive lens,
distances between adjacent lens groups changing during zooming from a wide-angle end to a telephoto end, with the second lens group G2, the third lens group G3, and the fourth lens group G4 moving toward the image side,
the sixth lens group G6 moving toward the image side and the seventh lens group G7 moving toward the object side when focusing from an infinite distance object to a close distance object,
the fifth lens G5 group including a vibration reduction lens group with negative refractive power and moving substantially perpendicularly relative to an optical axis for correcting image blur,
the vibration reduction lens group comprising a single positive lens and a single negative lens sequentially from the object side to the image side,
the large aperture ratio telephoto zoom lens satisfying following conditional expressions:
-
1.18
<
f
⁢
2
/
fT
<
-
0
.37
(
1
)
-
0.94
<
f
⁢
3
/
fT
<
-
0
.
3
⁢
5
(
2
)
67.
<
vn
(
3
)
0.018
<
Δ
⁢
PgFn
(
4
)
-
2.7
⁢
0
<
(
1
-
β
⁢
osT
)
×
β
⁢
RosT
<
-
0
.
5
⁢
2
(
5
)
-
0.42
<
β
⁢
bW
<
0
.
4
⁢
8
⁢
0
(
6
)
-
2.4
<
ff
/
fr
<
-
0
.64
(
7
)
0.63
<
f
⁢
1
/
fT
<
1.07
,
where
(
8
)
f2 represents a focal length of the second lens group G2,
fT represents a focal length of entire optical system at the telephoto end when focusing on infinity,
f3 represents a focal length of the third lens group G3,
νn represents a mean value of Abbe number of negative lenses used in the second lens group G2 and the third lens group G3,
ΔPgFn represents a mean value of anomalous dispersion of the negative lenses used in the second lens group G2 and the third lens group G3,
βosT represents a lateral magnification of the vibration reduction lens group at the telephoto end when focusing on infinity,
βRosT represents a lateral magnification of a lens system located closer to the image side than the vibration reduction lens group at the telephoto end when focusing on infinity,
βbW represents a combined magnification of a lens group located closer to the image side than the aperture diaphragm S at the telephoto end when focusing on infinity,
ff represents a focal length of the sixth lens group G6,
fr represents a focal length of the seventh lens group G7, and
f1 represents a focal length of the first lens group G8.

140 more elements

Dependencies are inferred from the claim text.

Large aperture ratio telephoto zoom lens

Life of this patent

Large aperture ratio telephoto zoom lens

Life of this patent

Abstract

Claims13