Variable magnification finder and imaging apparatus

Patent metadata

Field	Value
Publication number	US-9417504-B2
Application number	US-201414291607-A
Country	US
Kind code	B2
Filing date	May 30, 2014
Priority date	Dec 5, 2011
Publication date	Aug 16, 2016
Grant date	Aug 16, 2016

Abstract

The magnification of the variable magnification finder is switchable, and the finder includes a positive lens group, a negative lens group, and an eyepiece lens group in this order from an object side in a high magnification state. The positive lens group is retracted from an optical path of the variable magnification finder to the outside of the optical path and the negative lens group moves toward the object side when magnification is changed from the high magnification state to a low magnification state. The following conditional formula is satisfied when the focal length of the negative lens group is fN:

−15 mm<fN<−5 mm.

First claim

What is claimed is:

1. A variable magnification finder, the magnification of which is switchable, the finder comprising:
a positive lens group having positive refractive power;
a negative lens group having negative refractive power; and
an eyepiece lens group in this order from an object side in a high magnification state,
wherein the positive lens group is retracted from an optical path of the variable magnification finder to the outside of the optical path and the negative lens group moves toward the object side during magnification change from the high magnification state to a low magnification state, and
wherein the following conditional formula (1) is satisfied when the focal length of the negative lens group is fN:
−15 mm<fN<−5 mm   (1), and

wherein the variable magnification finder is a reverse-Galilean finder.

2. The variable magnification finder, as defined in claim 1 , wherein the negative lens group substantially consists of two negative lenses.

3. The variable magnification finder, as defined in claim 1 , wherein the negative lens group includes at least one aspherical surface.

4. The variable magnification finder, as defined in claim 1 , wherein the following conditional formula (2) is satisfied when the focal length of the positive lens group is fP:
20 mm<fP<60 mm   (2).

5. The variable magnification finder, as defined in claim 1 , wherein an optical path combination member for making a display on a display member arranged outside the optical path and a finder image observable by superimposing them one on the other is arranged in the optical path between the negative lens group and the eyepiece lens group.

6. The variable magnification finder, as defined in claim 1 , wherein the following conditional formula (1′) is satisfied:
−12 mm<fN<−7 mm   (1′).

7. The variable magnification finder, as defined in claim 1 , wherein the following conditional formula (2′) is satisfied when the focal length of the positive lens group is fP:
30 mm<fP<50 mm   (2′) .

8. The variable magnification finder, as defined in claim 2 , wherein the negative lens group includes at least one aspherical surface.

9. The variable magnification finder, as defined in claim 2 , wherein the following conditional formula (2) is satisfied when the focal length of the positive lens group is fP:
20 mm<fP<60 mm   (2).

10. The variable magnification finder, as defined in claim 2 , wherein an optical path combination member for making a display on a display member arranged outside the optical path and a finder image observable by superimposing them one on the other is arranged in the optical path between the negative lens group and the eyepiece lens group.

11. The variable magnification finder, as defined in claim 2 , wherein the following conditional formula (1′) is satisfied:
−12 mm<fN<−7 mm   (1′).

12. The variable magnification finder, as defined in claim 2 , wherein the following conditional formula (2′) is satisfied when the focal length of the positive lens group is fP:
30 mm<fP<50 mm   (2′).

13. An imaging apparatus comprising:
the variable magnification finder, as defined in claim 1 .

Assignees

• Fujifilm Corp

Inventors

• Saito Hiroki

Classifications

• H04N23/69

  Control of means for changing angle of the field of view, e.g. optical zoom objectives or electronic zooming · CPC title

• G02B23/145

  Zoom viewfinders · CPC title

• G03B13/06 Primary

  with lenses with or without reflectors · CPC title

• G03B13/10

  adjusting viewfinders field · CPC title

• H04N5/23296

  Electricity · mapped topic