Photography – Single lens reflex camera
Reexamination Certificate
2002-11-13
2004-02-17
Adams, Russell (Department: 2851)
Photography
Single lens reflex camera
C396S382000, C396S386000, C359S645000, C359S791000
Reexamination Certificate
active
06692163
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention relates to a single-lens reflex camera provided with an eyepiece which is constructed integrally with, or independently of, a photographic lens, and in particular, to a single-lens reflex camera provided with an eyepiece which has a photographing image plane of about half the size of a 135-mm film.
2. Description of Related Art
For the eyepiece of a finder system which has the image plane of 135F size, many proposals have been offered. In a camera whose image plane is small, when a conventional eyepiece is used as it is, only a small image can be observed. This increases an observer's fatigue in using the camera. Thus, in order to observe a large image through a finder, it is necessary to reduce the focal length of the eyepiece.
Conventional examples in which the focal length of the eyepiece is reduced are disclosed in Japanese Patent Publication Nos. Sho 57-60612 and Hei 7-107581 and Japanese Patent Preliminary Publication No. Hei 11-337847.
However, in any of these conventional examples, the image plane is of 135F size or a distance from the image plane to the eyepiece is short for the size of the image plane. This is not satisfactory for observing the large image through the finder.
SUMMARY OF THE INVENTION
It is, therefore, an object of the present invention to provide a single-lens reflex camera provided with an eyepiece in which even though the size of the photographing image plane is smaller than that of the 135-mm film and the finder has a long optical path length, a high magnification is obtained and a good view is afforded.
The single-lens reflex camera provided with an eyepiece according to the present invention includes a screen on which an image of an object is projected, a plurality of reflecting surfaces for erecting the image projected on the screen, and an eyepiece with positive refracting power for observing the image. In this case, the eyepiece has, in order from the object side, a first lens component with positive refracting power, a second lens component with positive refracting power, and a third lens component with negative refracting power and satisfies the following conditions:
0.15<tan
S
<0.35
2.00
<fb/Y
<5.00
−0.67
<f
3
/
f
<−0.25
where S is an angle made by the most off-axis chief ray passing through a point on an optical axis with the optical axis, at a distance of 23 mm along the optical axis from the exit surface of the third lens component, and refers to the angle at a diopter of 0 m
−1
when the eyepiece is moved; fb is a length, in terms of air, from the screen to the entrance surface of the first lens component, and refers to the length, in terms of air, at a diopter of 0 m
−1
when the eyepiece is moved; Y is a diagonal length of the image plane on the screen; f
3
is the focal length of the third lens component; and f is the focal length of the entire system extending from the screen to the exit surface of the eyepiece, and refers to the focal length of the entire system at the diopter of 0 m
−1
when the eyepiece is moved.
The single-lens reflex camera provided with an eyepiece according to the present invention includes a screen on which an image of an object is projected, a plurality of reflecting surfaces for erecting the image projected on the screen, and an eyepiece with positive refracting power for observing the image. In this case, the eyepiece has, in order from the object side, a first lens component with positive refracting power, a second lens component with positive refracting power, and a third lens component with negative refracting power and satisfies the following conditions:
0.15<tan
S
<0.35
−0.67
<f
3
/
f
<−0.37
The single-lens reflex camera provided with an eyepiece according to the present invention includes a screen on which an image of an object is projected, a plurality of reflecting surfaces for erecting the image projected on the screen, and an eyepiece with positive refracting power for observing the image. In this case, the eyepiece has, in order from the object side, a first lens component with positive refracting power, a second lens component with positive refracting power, and a third lens component with negative refracting power and satisfies the following conditions:
0.15<tan
S
<0.35
15 mm<
Y
<30 mm
The single-lens reflex camera provided with an eyepiece according to the present invention includes a screen on which an image of an object is projected, a plurality of reflecting surfaces for erecting the image projected on the screen, and an eyepiece with positive refracting power for observing the image. In this case, the eyepiece has, in order from the object side, a first lens component with positive refracting power, a second lens component with positive refracting power, and a third lens component with negative refracting power and satisfies the following conditions:
0.15<tan
S
<0.35
−0.67
<f
3
/
f
<−0.33
0.00
≦|f/f
23
|<0.258
where f
23
is a combined focal length of the second lens component and the third lens component and refers to the combined focal length of the second lens component and the third lens component at a diopter of 0 m
−1
when a distance between the second and third lens components can be adjusted.
In the single-lens reflex camera provided with an eyepiece according to the present invention, each of the first, second, and third lens components includes a single lens or a cemented lens.
In the single-lens reflex camera provided with an eyepiece according to the present invention, diopter adjustment is made by moving the first lens component alone.
In the single-lens reflex camera provided with an eyepiece according to the present invention, diopter adjustment is made by moving the first lens component and second lens component.
REFERENCES:
patent: 6088153 (2000-07-01), Anthon et al.
patent: 6181479 (2001-01-01), Koizumi
patent: 63-135914 (1988-06-01), None
patent: 57-60612 (1999-08-01), None
patent: 11-337847 (1999-12-01), None
patent: 11337847 (1999-12-01), None
Adams Russell
Blackman Rochelle
Olympus Optical Co, Ltd.
Pillsbury & Winthrop LLP
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