US 2026/0036795 A1Published application

Variable magnification optical system

AssigneeSigma Corporation

InventorRyo SHIOTA

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Abstract

A variable magnification optical system that is relatively compact while suppressing various aberrations such as spherical aberration and field curvature over the entire variable magnification range. The variable magnification optical system includes, in order from the object side, a first lens group G1 having a negative refractive power, a second lens group G2 having a positive refractive power, a third lens group G3 having a positive refractive power, and an image surface side lens group GR. During variable magnification from the wide-angle end to the telephoto end, the air distance between the first lens group G1 and the second lens group G2 decreases, the air distance between the second lens group G2 and the third lens group G3 changes, and the air distance between the third lens group G3 and the image surface side lens group GR increases. The variable magnification optical system satisfies predetermined conditional expressions.

A variable magnification optical system comprising,

in order from an object side:
a first lens group G1 having a negative refractive power;
a second lens group G2 having a positive refractive power;
a third lens group G3 having a positive refractive power;
and
an image surface side lens group GR,
wherein, during variable magnification from a wide-angle end to a telephoto end:
an air distance between the first lens group G1 and the second lens group G2 decreases;
an air distance between the second lens group G2 and the third lens group G3 changes;
and
an air distance between the third lens group G3 and the image surface side lens group GR increases, and the optical system satisfies following conditional expressions:
-
0.08
<
(
D
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2
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3
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T
-
D
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2
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3
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W
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D
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12
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W
-
D
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1
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2
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0.08
;
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1
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(
D
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2
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N
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and
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where:
D12W is a distance between the first lens group G1 and the second lens group G2 at a wide-angle end;
D12T is a distance between the first lens group G1 and the second lens group G2 at a telephoto end;
D23W is a distance between the second lens group G2 and the third lens group G3 at the wide-angle end;
D23N is a distance between the second lens group G2 and the third lens group G3 at an intermediate variable magnification state;
D23T is a distance between the second lens group G2 and the third lens group G3 at the telephoto end;
D34W is a distance between the third lens group G3 and the image surface side lens group GR at the wide-angle end;
D34T is a distance between the third lens group G3 and the image surface side lens group GR at the telephoto end;
fw is a focal length of entire lens system at the wide-angle end when focused at infinity;
ft is a focal length of the entire lens system at the telephoto end when focused at infinity;
and
the intermediate variable magnification state refers to a state in which the focal length of the entire optical system, due to variable magnification, is equal to or near √(fw×ft).

186 more elements

Facts

Application

19/258,186Filed 2 Jul 2025

Priority

JP 2024-1264932 Aug 2024

Published

5 Feb 2026

Term ends

Not estimatedThe source records don’t support an estimate.

Classification4 codes

G02B 15/1465
Having more than five groups: the first group being negative
G02B 15/16
By axial movement of one or more lenses or groups of lenses relative to the image plane for continuously varying the equivalent focal length of…:…
G02B 15/20
With interdependent non-linearly related movements between one lens or lens group, and another lens or lens group: having an additional movable…
G02B
Optical elements, systems or apparatus

Abstract

Claims11