Variable magnification optical system, optical equipment, and method for producing variable magnification optical system
AssigneeNikon Corporation
InventorKeisuke TSUBONOYA
Life of this patent
Estimating the term…
Abstract
A variable magnification optical system which comprises, in order from an object side, a first lens group having negative refractive power, a second lens group having positive refractive power and a third lens group; upon varying magnification, distances between the neighboring respective lens groups being varied; upon focusing, the first lens group and the second lens group being moved along the optical axis; and predetermined conditional expression(s) being satisfied, whereby the variable magnification optical system is made in small in size, and can correct superbly various aberrations.
Claims21
A variable magnification optical system comprising, in order from an object side, a first lens group having negative refractive power, a second lens group having positive refractive power, and a third lens group;
- upon varying magnification, intervals between the neighboring respective lens groups being varied;
- upon focusing, the first lens group and the second lens group being moved along the optical axis;
- and
- the following conditional expression being satisfied:
- 1.00
- <
- (
- -
- f
-
-
- 1
- )
-
- /
-
- f
-
-
- 2
- <
- 3.00
- where f1 denotes a focal length of the first lens group, and f2 denotes a focal length of the second lens group.
A variable magnification optical system comprising, in order from an object side, a first lens group having negative refractive power, a second lens group having positive refractive power, and a third lens group;
- upon varying a magnification, intervals between the neighboring respective lens groups being varied;
- and
- the first lens group and the second lens group each comprising at least one convex-shaped air lens.
A method for manufacturing a variable magnification optical system comprising, in order from an object side, a first lens group having negative refractive power, a second lens group having positive refractive power and a third lens group,
- the method comprising step of:
- constructing such that, upon varying magnification, intervals between the neighboring respective lens groups are varied,
- the method further comprising at least one of the following steps A and B:
- the step A including:
- constructing such that, upon focusing, the first lens group and the second lens group are moved along the optical axis;
- and
- constructing such that the following conditional expression is satisfied:
- -
- 1.00
- <
- (
- -
- f
-
-
- 1
- )
-
- /
-
- f
-
-
- 2
- <
- 3.00
- where f1 denotes a focal length of the first lens group, and f2 denotes a focal length of the second lens group,
- the step B including:
- constructing such that the first lens group and the second lens group each comprises at least one convex-shaped air lens.
Dependencies are inferred from the claim text.