JP3402814B2 - Camera system - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a camera system,
Especially, the still image capturing system for recording a still image on a recording medium (silver salt film) and the moving image are a solid-state image sensor (CCD).
Image on the surface and the electrical signal is magnetic medium (magnetic tape)
The present invention relates to a camera system, such as a video camera with a still camera, having a shooting system of a video camera for recording the same.

[0002]

2. Description of the Related Art Conventionally, various camera systems (video cameras with a still camera) having both the functions of a still camera and the functions of a video camera have been proposed.

For example, in US Pat. No. 3,546,375, a movable mirror is arranged in the optical path of an objective lens for photographing, and a position of the movable mirror is selectively switched to record a still image and a moving image on different recording media. What has been done is disclosed. Further, Japanese Utility Model Application Laid-Open No. 57-96444 discloses a main body of a video camera in which an optical photographing section for photographing a silver salt film is integrally or separately provided on the main body in a detachable manner.

Further, Japanese Laid-Open Patent Publication No. 63-205626 discloses a single-lens reflex still camera in which a reduction optical system is arranged on the back cover side to form an object image on a solid-state image pickup device for a video camera. In Japanese Patent Laid-Open No. 63-276012, a reduction optical system is arranged behind a lens for a single lens reflex camera,
It is proposed to be used for G and EFP cameras.

Further, JP-A-63-148773, JP-A-63-237738, and JP-A-63-24773.
No. 6, JP-A-63-247738 and JP-A-63-261330 all combine the functions of a still camera and the functions of a video camera to capture both still and moving images. It is configured to be able to.

[0006]

The conventional camera system such as a video camera with a still camera does not have a structure for recording still images and moving images at the same angle of view at the same time, and thus it is difficult to use. there were. Further, in the conventional camera system, when dust or dust enters the optical system, the dust or dust is reflected in a part of the moving image as the solid-state image sensor is downsized, and the image quality is deteriorated. There was a problem.

The present invention forms an object image on a primary image forming surface with a photographing system for a still image and a light flux passing through the photographing system, and re-images the object image on a CCD or the like to obtain a moving image. At this time, a still image and a moving image can be simultaneously recorded by appropriately configuring a moving image (video image) photographing system, and dust can be collected in a space where the primary image forming surface of the moving image optical system is located. Another object of the present invention is to provide a camera system capable of obtaining a high-quality image by preventing dust and the like from entering, and even if such dust and the like do not appear in a moving image.

[0008]

In a camera system of the present invention, a light flux from a subject that has passed through a photographing lens is divided into a plurality of light fluxes by a first optical member, and the first light flux of the plurality of light fluxes is stationary. A subject image is formed on a recording medium for images, a subject image is formed on the primary image forming surface in the field lens system by the second light flux, and the subject image on the primary image forming surface is a moving image by a reduction lens. System for re-imaging on a recording medium for automobiles
A is, the field lens system has a plurality of lenses, setting Then co as the primary image plane in the space formed by the two lens surfaces of the plurality of lenses is positioned
From the primary image plane to the lens surface closest to the optical axis.
At L, the diagonal image height of the primary image plane is y ₁ , the moving image
The diagonal image height of the image recording medium is y ₂ , and the recording medium for the moving image is
When the diagonal length of the body is Y and β = y ₁ / y ₂ , it is characterized in that the condition 0.0075 · β ² · Y <L (1) is satisfied .

[0009]

Embodiment 1 FIG. 1 is a sectional view of the essential portions of Embodiment 1 of the present invention. In FIG. 1, reference numeral 1 denotes an exterior cover, which is made up of a plurality of members including fastening members such as screws and accommodates each element. A lens unit 2 has a plurality of lens elements L1 to L4 and a lens barrel 3, and forms an object image on a silver salt film 5 as a recording medium for still images. The lens barrel 3 holds the lens elements L1 to L4.
An image pickup device for a still image may be used instead of the silver salt film 5.

In this embodiment, each lens element L1 to L
4 constitutes a zoom lens ZL. The zoom lens ZL has a variable power lens element group that can move on the optical axis in conjunction with an automatic or manual zoom operation, a focusing lens element group that is driven by information from an automatic focus adjustment device to be described later, and the like. ing. Reference numeral 4 denotes an iris diaphragm provided in the zoom lens ZL for silver salt still photography (for silver salt photography).

A shutter device 6 is arranged immediately in front of the silver salt film 5 and is composed of a shutter curtain 6a, a shutter frame 6b and the like. Reference numeral 7 denotes a semi-transparent thin film mirror (half mirror) as a first optical member, which is a silver salt film 5 for still images of light fluxes from a subject.
And a solid-state image sensor as a recording medium for a video image described later. 7a is a zoom lens (L1 to L
5) The optical axis of ZL, 7b is the optical axis that passes through the half mirror 7 and reaches the silver salt film 5 side, and 7c and 7d are the optical axes reflected by the half mirror 7.

The zoom lens ZL forms an object image on the surface of the silver salt film 5 and the primary image forming surface (position) 5a optically conjugate with the silver salt film 5 via the half mirror 7. 8
Reference numeral (8a, 8b) is a field lens having a positive refractive power, which has two lenses 8a and 8b, and the primary image forming surface 5a is located between the lenses 8a and 8b. The field lens 8 guides an object image (aerial image) formed on a position (primary image forming surface) 5a conjugate with the silver salt film 5 through a mirror 9 toward a subsequent reduction lens unit 10 having a positive refractive power. It is shining.

Further, the field lens 8 adjusts the pupil of the object image. The two lenses 8a and 8b forming the field lens 8 and the lens barrel (not shown) holding the two lenses form a sealed structure in the space where the primary image forming surface 5a is located. The reduction lens unit 10 has a video diaphragm unit 11, and re-images the object image formed on the primary image forming surface 5 a on the surface of a solid-state image sensor (CCD) 13 via an optical low-pass filter 12.

Then, the image information regarding the moving image (video image) is obtained from the CCD 13. Reference numeral 14 denotes a movable sub-mirror, which is removably arranged behind the half mirror 7 and guides the photographing light flux passing through the half mirror 7 to the automatic focus detection device 15.

The automatic focus detection device 15 in this embodiment uses a so-called phase difference shift detection method known in the related art, and is generated by a light beam that has passed through a plurality of different regions on the pupil plane of a photographing lens (zoom lens). The defocus amount and the defocus direction on the silver salt film surface 5 are detected by comparing a plurality of object images.

In this embodiment, the solid-state image pickup device 1 is always used.
Since a subject image is obtained on the solid-state image pickup device 3,
The focus detection method based on the high-frequency video signal from 3, that is, the so-called blurring automatic focus adjustment may be used, or the combination method of the shift method of the present embodiment may be used.

Reference numeral 16 denotes a movable light-shielding plate which prevents leakage of light flux when the half mirror 7 is used. Shading plate 1
6 is retracted from the optical path at the time of shooting. Reference numeral 17 denotes a back lid unit, which is provided so as to be openable and closable when the silver salt film 5 is loaded.

In this embodiment, the case where a 135 type silver salt film is used is shown, but the invention is not limited to this.
There is no problem even if the film is a drop-in type or a disc type.

Reference numeral 18 denotes an electronic viewfinder unit, which outputs an image to a small liquid crystal 19 for monitoring the image signal from the solid-state image pickup device 13 and observes it through a reflecting mirror 20 and an eyepiece lens 21. The electronic viewfinder unit 18 is rotatable about a rotary shaft 22 as a spindle.

In the present embodiment, the iris diaphragm 4 for silver salt still photography is always kept open during the shooting of video moving images, and is narrowed down to a predetermined diameter when the release switch for silver salt still photography is pushed. Be done. At the time of shooting a video moving image, the exposure control is performed only by the video aperture unit 11 in the reduction lens unit 10, and the solid-state image sensor 1 is used as necessary.
Proper exposure is obtained by changing the accumulation time to 3 and the gain of the signal processing system.

Reference numeral 23 denotes a secondary battery, which is detachably attached to the lower part of the device and is a common single power source for supplying all the power used by the device. 25 is a barrier,
It is provided in front of the lens unit 2 so as to be openable and closable, and incorporates a strobe 24. Reference numeral 26 is a microphone for recording audio during video shooting, and 27 is an external terminal as an interface with an external device such as a television or a stereo device.

2 and 3 are explanatory views of the optical systems of Examples 1 and 2 in which the field lens 8 and the reduction lens unit 10 of FIG. 1 are shown with their optical paths expanded.

2 and 3 show a zoom lens ZL (not shown).
2 shows an optical path in which the object image formed on the primary image forming surface 5a is reduced and re-imaged on the surface of the CCD 13 by the field lens 8 (8b) and the reduction lens unit 10 via the optical low pass filter 12.

In this embodiment, the first optical member 7 is arranged between the zoom lens ZL and the image plane (silver salt film) 5 to divide the light flux passing through the zoom lens ZL into a plurality (two). Object images are formed on the image plane 5 for obtaining a still image such as a silver salt film or an image sensor and the primary image plane 5a in the field lens 8.

Of these, the object image formed on the primary image forming surface 5a is reduced and re-formed on the surface of the CCD 13 for obtaining a moving image by the reduction lens unit 10 via the field lens 8 and the mirror 9. At this time, the field lens 8 is composed of a plurality of lenses (in the present embodiment, it is composed of two lenses 8a and 8b, but it may be two or more).
Each element (paraxial refractive power arrangement) is set so that the next image forming surface is located between the lenses 8a and 8b, and the primary image forming surface 5
The space including a has a sealed structure. As a result, the space in the lens system where the primary image plane 5a is located is a sealed space,
We try to prevent dust from entering the space.

In the present embodiment, the distance on the optical axis from the primary image forming surface 5a to the closest lens surface is L, and the primary image forming surface 5a.
Let y _{1 be} the upper diagonal image height, y _{2 be} the diagonal image height on the moving image recording medium (CCD) 13 as the secondary image plane, and Y be the diagonal length of the moving image recording medium. = Y ₁ / y ₂ 0.0075 · β ² · Y <L ·························· satisfies (1).

As a result, even if dust enters the space where the primary image forming surface 5a is located and adheres to the lens surface, the dust is generated by setting the distance between the primary image forming surface and the lens surface appropriately. It is set so that it is not recognized on the CCD surface.

Next, numerical examples 1 and 2 of the field lens 8 shown in FIGS. 2 and 3 will be described below. In the numerical example, Ri is the radius of curvature of the ith lens surface from the object side (zoom lens ZL), D1 and D2 are the lens thicknesses of the field lenses 8a and 8b, and Ni and νi are the refraction of the material of the field lenses 8a and 8b. Ratio and Abbe number, L1 is field lens 8a
From the lens surface behind the lens to the primary image plane 5a, L2
Is the distance from the primary image plane 5a to the lens surface in front of the field lens 8b. Y is the diagonal length of the CCD 13,
β is a ratio (y ₁ / y ₂ ) where y _{1 is the} diagonal image height on the primary imaging surface 5 a and y ₂ is the diagonal image height on the CCD 13 surface.

<Numerical Example 1> Focal length of reduction lens (10) f = 10.450 nm Y = 4.5 β = 7.69 L = L1 = L2 = 2.0 <Numerical example 2> Focal length of reduction lens (10) f = 10.546 nm Y = 4.5 β = 7.69 L = L2 = 5.1

[0030]

According to the present invention as geostationary images and moving images at the same time and dust or the like into a space primary image forming plane of the optical system of the moving image is located as well as the recording does not enter, and It is possible to achieve a camera system capable of obtaining a high-quality image by preventing these dusts and particles from appearing in a moving image even if it intrudes.

[Brief description of drawings]

FIG. 1 is a schematic view of a main part of a first embodiment of the present invention.

FIG. 2 is a lens cross-sectional view of Example 1 of the reduction optical system in FIG.

FIG. 3 is a lens cross-sectional view of Example 2 of the reduction optical system in FIG.

[Explanation of symbols]

1 Exterior cover 2 lens unit 3 lens barrel 4 aperture 5 silver salt film 6 Shutter mechanism 7 Half mirror (first optical member) 8 field lens 9 mirror 10 Reduction lens unit 11 aperture 12 Optical low-pass filter 13 Solid-state image sensor

Claims (2)

(57) [Claims] 1. A light flux from a subject that has passed through a taking lens is divided into a plurality of light fluxes by a first optical member, and a first light flux of the plurality of light fluxes forms a subject image on a recording medium for still images. second a light beam of an object image formed on the primary image forming plane in the field lens system, turtles to re-imaged recording medium for a moving picture by the reduction lens an object image on the primary image forming plane with
The field lens system has a plurality of lenses, and is set so that the primary image plane is located in a space formed by two lens surfaces of the plurality of lenses.
And the lens closest to the optical axis direction from the primary image plane.
The distance to the lens surface is L, and the diagonal image height of the primary image plane is
y ₁ , the diagonal image height of the recording medium for the moving image is y ₂ , the moving image
The diagonal length of the recording medium for image and _{Y, β = y 1 / y} 2 Far
The camera system is characterized by satisfying the following condition : 0.0075 · β ² · Y <L . 2. The camera system according to claim 1, wherein the space in which the primary image plane is located has a sealed structure.