Optical system and optical device provided therewith

Patent metadata

Field	Value
Publication number	US-10466453-B2
Application number	US-201514694911-A
Country	US
Kind code	B2
Filing date	Apr 23, 2015
Priority date	Oct 23, 2012
Publication date	Nov 5, 2019
Grant date	Nov 5, 2019

Abstract

An optical system comprises a first lens group G1 disposed in a most object side and having positive refractive power, a stop member ST disposed at an image side of the first lens group G1, and a second lens group G2 disposed at an image side of the stop member ST. A predetermined conditional expression is satisfied, whereby light beyond the maximum angle of view collected on the focal point position of a most object side lens group having positive refractive power is reduced, so that heat generated by a member in the vicinity of the focal point position is reduced.

First claim

What is claimed is:

1. An optical system comprising:
a first lens group disposed most toward an object side in the optical system and having positive refractive power,
a second lens group disposed at an image side of the first lens group,
an aperture stop,
a stop member provided in addition to the aperture stop and disposed next to the first lens group between the first lens group and the second lens group,
and
one or more lens groups disposed on the image side of the second lens group,
wherein the optical system is adapted to vary magnification,
upon varying magnification from a wide angle end state to a telephoto end state, a distance between the second lens group and the stop member varies, and
the following conditional expressions are satisfied:
0.20 <ds/f 1<0.60
1.00×φ2<φs<0.8×φ1  (unit: mm)

where ds denotes a distance in a telephoto end state along an optical axis between a lens surface of a most image side lens in the first lens group and the stop member, f1 denotes a focal length of the first lens group, φ1 denotes an outer diameter of a most image side lens in the first lens group, φ2 denotes an outer diameter of a most object side lens in the second lens group, and φs denotes a diameter of an aperture of the stop member.

2. The optical system according to claim 1 , wherein an aperture diameter of the stop member is larger than an effective diameter of the optical system in a position of the stop member along an optical axis.

3. The optical system according to claim 1 , wherein
upon varying magnification from a wide angle end state to a telephoto end state, a distance between the first lens group and the second lens group varies.

4. The optical system according to claim 1 , wherein
upon varying magnification from a wide angle end state to a telephoto end state, a distance between the first lens group and the stop member varies.

5. The optical system according to claim 1 , wherein
the optical system further comprises a moving mechanism for moving the stop member along the optical axis, upon varying magnification from a wide angle end state to a telephoto end state.

6. The optical system according to claim 1 , wherein the stop member has an anti-reflection member on a surface.

7. The optical system according to claim 1 , wherein a position of an optical axis side end of the stop member in a direction of an optical axis is at a more image side than a position of a barrel side end of the stop member in the direction of the optical axis.

8. An optical apparatus equipped with the optical system according to claim 1 .

9. The optical system according to claim 1 , wherein an aperture diameter of the stop member is fixed.

10. A method for manufacturing an optical system comprising a first lens group disposed most toward an object side in the optical system and having positive refractive power, a second lens group disposed at an image side of the first lens group, an aperture stop, a stop member provided in addition to the aperture stop and disposed next to the first lens group between the first lens group and the second lens group, and one or more lens groups disposed on the image side of the second lens group,
the method comprising:
arranging the lens groups and the stops such that the optical system is adapted to vary magnification, and
such that, upon varying magnification from a wide angle end state to a telephoto end state, a distance between the second lens group and the stop member varies, and
satisfying the following conditional expressions:
0.20 <ds/f 1<0.60
1.00×φ2<φ s< 0.8×φ1(unit: mm)

where ds denotes a distance in a telephoto end state along an optical axis between a lens surface of a most image side lens in the first lens group and the stop member, f1 denotes a focal length of the first lens group, φ1 denotes an outer diameter of a most image side lens in the first lens group, φ2 denotes an outer diameter of a most object side lens in the second lens group, and φs denotes a diameter of an aperture of the stop member.

Assignees

• Nikon Corp

Inventors

• Ishigami Hiroyuki
• Shimizu Kunihiko
• Obama Akihiko
• Hamasaki Takuji

Classifications

• G02B15/20

  having an additional movable lens or lens group for varying the objective focal length · CPC title

• G02B27/646

  compensating for small deviations, e.g. due to vibration or shake (movement of one or more optical elements for control of motion blur in cameras, projectors or printers G03B2205/0007; image stabilisation in cameras peculiar to the presence or use of an electronic image sensor H04N23/68) · CPC title

• G02B13/18 Primary

  with lenses having one or more non-spherical faces, e.g. for reducing geometrical aberration {(G02B13/002 takes precedence)} · CPC title

• G02B1/11

  Anti-reflection coatings · CPC title

• G02B9/10

  one + and one - component · CPC title