JP2010193386A - Camera - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a camera capable of providing an image with reduced color irregularity even when low sensitivity is designated. <P>SOLUTION: The camera includes: an photographic lens (23); an imaging element (15) for imaging an image by receiving light from the photographic lens (23); a dimming means (10) taking an advancing position (M) intersecting with an optical path from the photographic lens (23) to the imaging element (15) and an evacuating position (N) deviating from the optical path; a storage means (33) to store an optical characteristic of light having passed through the dimming means (10); and a correction means (45) to correct the image imaged by the imaging element (15) by the optical characteristic stored by the storage means (33). <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a camera whose sensitivity can be changed.

In digital cameras, the minimum sensitivity of an image sensor is often set to ISO200, for example. However, for example, when shooting with a wide open aperture in a bright place or when shooting with a slow shutter, lower sensitivity is desired. Also, in shooting in a studio or the like, a lower ISO sensitivity may be desired in order to easily control the flash emission. In such a case, it is possible to cope with a low ISO sensitivity by changing the gradation characteristics by image processing. However, changing the gradation characteristics may cause a reduction in image quality.
For this reason, conventionally, there is a camera that uses a quick return mirror as a half mirror and performs shooting while keeping the half mirror on the optical path when a low sensitivity is designated (see, for example, Patent Document 1).

Japanese Patent Laid-Open No. 2001-17761

  As the half mirror, for example, a pellicle mirror in which a thin film is subjected to vapor deposition is generally used. However, it is difficult to make the vapor deposition strictly uniform over the entire mirror, resulting in slight vapor deposition unevenness on the surface. For this reason, color unevenness also occurs in the light passing through the half mirror, which may affect the captured image.

  An object of the present invention is to provide a camera capable of obtaining an image with little color unevenness even when low sensitivity is designated.

  The present invention solves the above problems by the following means. In addition, in order to make an understanding easy, although the code | symbol corresponding to embodiment of this invention is attached | subjected and demonstrated, it is not limited to this.

According to the first aspect of the present invention, an imaging unit (15) that captures an image that captures light from the photographing lens (23), and an advancing that intersects an optical path from the photographing lens (23) to the imaging unit (15) A dimming means (10) movable between a position (M) and a retracted position (N) deviating from the optical path, and a storage means (33) for storing optical characteristics of light transmitted through the dimming means (10) And a correction means (45) for correcting the image picked up by the image pickup unit (15) by the optical characteristics stored in the storage means (33). is there.
The invention according to claim 2 is the camera (1) according to claim 1, wherein the dimming means is a half mirror (10), and the half mirror (10) is the photographing lens (23). ) To an imaging position (M) that intersects the optical path from the imaging unit (15) to reflect the subject light and provide a visible image to the optical viewfinder (7) provided in the camera. This is a camera (1) characterized by the above.
The invention according to claim 3 is the camera (1) according to claim 1 or 2, wherein the optical characteristics are incident on the camera (1), pass through the dimming means (10), The camera (1) is characterized by uneven color in the light imaged by the imaging unit (15).
The invention according to claim 4 is the camera (1) according to any one of claims 1 to 3, wherein a plurality of the correction values are stored corresponding to the color temperature of the incident light. The camera (1) characterized by the above.
The invention according to claim 5 is the camera (1) according to any one of claims 4, wherein the color temperature of the subject light is other than the color temperature at which the optical characteristics are stored. The camera (1) is characterized in that an optical characteristic corresponding to the subject light is obtained by calculation from a color temperature in which the optical characteristic is stored.
Invention of Claim 6 is a camera (1) of any one of Claims 1-5, Comprising: When the sensitivity of the said imaging part (15) is set more than 1st sensitivity The dimming means (10) is retracted from the path during shooting, and the dimming means (10) is set during shooting when the sensitivity of the imaging unit (15) is set to be lower than the first sensitivity. The camera (1) is characterized in that shooting is performed while the camera is advanced in the path.
Note that the configuration described with reference numerals may be improved as appropriate, or at least a part thereof may be replaced with another component.

  According to the present invention, it is possible to provide a camera capable of obtaining an image with little color unevenness even when low sensitivity is designated.

It is internal sectional drawing which shows the camera of one Embodiment of this invention. It is a block diagram which shows the circuit structure of the camera of one Embodiment. It is a side view at the time of setting a parameter. It is the front view which divided | segmented CCD. It is a flowchart explaining operation | movement.

  Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 shows a camera 1 according to an embodiment of the present invention. The camera 1 is a digital single-lens reflex camera, and includes a camera body 2 and a lens barrel 3 that is detachably attached to the camera body 2.

  A half mirror 10 is disposed inside the camera body 2. The half mirror 10 reflects a part of the photographing light from the lens barrel 3 and guides it to the finder 7 on the observation optical path B, and transmits a part of the photographing light to the imaging element 15 on the photographing optical path A. The half mirror 10 is a quick return mirror that can rotate around the rotation axis 11, and moves between a position M that intersects the imaging optical path A and a position N that intersects the observation optical path B by the rotation. At the position N, the half mirror 110 is retracted from the photographing optical path A.

  On the back side of the half mirror 10, a shutter 14 and an image sensor 15 are sequentially arranged. The image sensor 15 is a solid-state image sensor such as a CCD that converts incident subject light into an electrical signal. Hereinafter, the image sensor 15 is also referred to as a CCD 15. As will be described later, the sensitivity of the CCD 15 is variable in a plurality of stages, and the sensitivity is set by a photographer's operation on the operation unit 35 (see FIG. 2).

  A liquid crystal monitor 17 is disposed on the back side of the CCD 15. The liquid crystal monitor 17 displays live view display for projecting the subject, set ISO, shutter speed, and other shooting conditions.

  A focusing screen 18 is arranged on the upper part of the half mirror 10. The focusing screen 18 is a screen that forms an image of the photographing light reflected by the half mirror 10, and is disposed between the half mirror 10 and the pentaprism 19.

  The pentaprism 19 is an optical element that is disposed above the focusing screen 18 and guides an image formed on the focusing screen 18 to the finder 7 and the photometry device 20 as an erect image. The photometric device 20 calculates an appropriate exposure according to the set ISO sensitivity and subject light intensity. Between the pentaprism 19 and the finder 7, an eyepiece lens 21 that enlarges the subject image is disposed.

  The lens barrel 3 includes a photographing optical system 5 having a plurality of lenses 23 and a diaphragm 24 and is attached to a lens mount of the camera body 2.

In the above structure, the CCD 15 can be set to ISO 200, 400, 800, 1600 having normal sensitivity and ISO 100 having low sensitivity. Here, the minimum sensitivity that can be set by the CCD 15 without changing the gradation characteristics is ISO200.
In photographing with normal sensitivity, first, the half mirror 10 advances into the photographing optical path M and guides a part of the subject light to the photometric device 20, whereby photometry is performed and exposure conditions are determined. Then, when a release switch (not shown) is pressed, the half mirror 10 jumps up and retracts from the photographing optical path M. As a result, all the subject light enters the CCD 15 and photographing is performed.

  On the other hand, when the low-sensitivity ISO 100 is selected, shooting is performed with the half mirror 10 inserted in the shooting optical path M. For example, when the transmittance of the half mirror 10 is 50%, 50% of the subject light is guided to the finder 7 by the half mirror 10 with the sensitivity of the CCD 15 set to 200, and the remaining 50% of the subject. Shooting with light.

  Here, in the present embodiment, the half mirror 10 uses a pellicle mirror. The pellicle mirror achieves translucency by coating a thin film. This coating is difficult to achieve completely uniformly and may result in uneven portions. For this reason, in such shooting through the half mirror 10, the optical characteristics may change, causing color unevenness and non-uniformity of the light reduction rate, which may degrade the image quality of the shot image. In addition, as another factor of this non-uniformity, the half mirror 10 may be inserted obliquely with respect to the optical axis.

  FIG. 2 is a block diagram showing a circuit configuration for correcting this change in optical characteristics. As shown in FIG. 2, a main control unit 31, an image control unit 32, an image memory 33, an operation unit 35, a CCD drive circuit 36, a half mirror drive circuit 37, a data memory 38, an A / D converter 43, and the like are provided. .

  The main control unit 31 controls the operation of the camera 1. The CCD drive circuit 36 generates a clock for instructing the operation timing of the CCD 15 and outputs it to the CCD 15 to control the start of photoelectric conversion, the output of charges accumulated by the photoelectric conversion, and the like. The half mirror drive circuit 37 outputs an instruction signal to the actuator for driving the half mirror 10 to control the rotation of the half mirror 10.

  The operation unit 35 is operated for various selections and settings such as pressing the release switch and a CCD sensitivity setting button. In the present embodiment, the operation unit 35 has a half mirror shooting button (not shown) that can select a shooting mode in which shooting is performed with the half mirror 10 entering the optical path of the subject and stopped. .

The A / D converter 43 converts the signal from the CCD 15 into a digital signal and outputs it to the image control unit 32.
The image control unit 32 generates image data by performing processing such as pixel interpolation, color balance, and gamma correction on the digital signal from the A / D converter 43. The processed image data is stored in the image memory 33.

In the present embodiment, the main control unit 31 includes an adjustment unit 44 and a correction unit 45.
The adjustment unit 44 sets a correction value necessary for the CCD 15 when photographing when the half mirror 10 is in the optical path of the subject light. The correction value required for the CCD 15 is to suppress deterioration of the image quality of the photographed image when the optical characteristics change and color unevenness or non-uniformity of the light reduction rate occurs during photographing through the half mirror 10. It is a correction value. The correction value by the adjustment unit 44 is set prior to shipment of the camera 1. The set correction value is stored in a data memory 38 such as a ROM or a RAM provided in the main control unit 31.
The correction unit 45 corrects the captured image data based on the correction value stored in the data memory 38.

  Next, the correction value set by the adjustment unit 44 will be specifically described with reference to FIGS. In photographing through the half mirror 10, nonuniform color distribution, that is, color unevenness occurs.

  As shown in FIG. 3, the diffusion plate 50 is set so as to be in close contact with the lens barrel 3 of the camera 1 before shipment, and light of two color temperatures is irradiated from the light source 51 in the close contact state of the diffusion plate 50. To shoot. The diffuser plate 50 is used for uniformly diffusing the light from the light source 51 and photographing a uniform image. At this time, the half mirror 10 is brought into a state where the mirror is lowered to enter the photographing optical path.

  In the state of FIG. 3, for example, photographing is performed under two lights of red light having a color temperature of about 3200 Kelvin and blue light having a color temperature of about 5100 Kelvin. At the time of photographing, the CCD 15 divides into a plurality of areas as shown in FIG. 4 and measures the R / G value and B / G value in each block. In this case, each block is specified by XY coordinates, and the XY coordinates of each block are stored in the data memory 38.

The adjustment unit 44 performs white balance adjustment on the measurement values (R / G value and B / G value) with light having different color temperatures. The white balance adjustment is to set parameters for setting the obtained R / G value and B / G value to “1”.
In the white balance adjustment, when the R / G value of the central block L1 in FIG. 4 is 0.9 and the B / G value is 0.8, the R / G value is “1” and the B / G value is “ 1 ”is performed by multiplying the entire block by the reciprocal number.

Even when the white balance adjustment is performed in this way, as described above, color unevenness exists in the half mirror 10. For this reason, for example, the R / G value and the B / G value may not be 1 in the block L2 around the CCD 15 shown in FIG.
Therefore, for each individual block, an R / G value and an inverse number to be multiplied to set the B / G value to “1” are calculated, and the calculated parameter (optical characteristic) is associated with the XY coordinates of the block L2.

  The adjustment unit 44 outputs the parameters calculated as described above to the data memory 38, and the data memory 38 stores the parameters together with the XY coordinates in correspondence with the color of the light source at that time.

  When shooting through the half mirror 10 is performed, the correction unit 45 adjusts the white balance according to the light source, and then calls the parameters of each block from the data memory 38 to perform the shooting on the captured image data. Multiply the parameters of each block. As a result, the color unevenness of the image passing through the half mirror 10 can be corrected.

  Here, the parameters are stored for two types of cases where the color temperature is 3200 Kelvin and the color temperature is 5100 Kelvin. When the actual subject light at the time of shooting is light at a temperature other than those stored in the data memory 38, the parameter corresponding to the current subject light is determined from the correction value at 3200 Kelvin and the parameter at 5100 Kelvin. This parameter is used as a correction value obtained by interpolation by calculation. As a result, the image passing through the half mirror 10 can be corrected as described above.

  FIG. 5 is a flowchart for performing imaging using the half mirror 10 after the correction parameters are set as described above.

  In step S11, the sensitivity of the CCD 15 selected by the photographer is determined. If the ISO sensitivity is 100, the process proceeds to step S12. If the ISO sensitivity is 200 or more, the process proceeds to step S22.

  Next, the release switch is pressed (step S12), but when the ISO sensitivity is 100, the mirror is not raised (step S13). Then, the shutter 14 is opened (step S14), exposure is performed (step S15), and then the shutter 14 is closed (step S16).

  The white balance adjustment is performed on the image of the CCD 15 obtained by the exposure in step S15 (step S17), and then correction processing is performed for each block of the CCD 15 (step S18). Thereby, an image in which color unevenness is suppressed is obtained. Thereafter, after the image control unit 32 performs processing, the image is stored in the image memory 33 (step S19).

  On the other hand, when the ISO sensitivity is 200 or more, the process proceeds to step S22, and when the release switch is pressed (step S22), the mirror is raised (step S23), the shutter 14 is opened (step S24), and the exposure is performed (step). Thereafter, the shutter 14 is closed (step S26). The image is subjected only to normal white balance processing (step S27), and the image is stored in the image memory 33 (step S19).

As described above, this embodiment has the following effects.
(1) Since the captured image data is corrected when shooting is performed with the half mirror 10 entering the optical path of the subject, color unevenness caused by the half mirror 10 can be suppressed.
(2) Since photography can be performed through the half mirror 10, photography with low ISO sensitivity is possible, photography can be performed according to the needs of the photographer, and the degree of photography freedom increases.

(Deformation)
The present invention is not limited to the above-described embodiment, and various modifications and changes as described below are possible, and these are also within the scope of the present invention.
(1) In the present embodiment, the subject light is dimmed using the half mirror 10, but the present invention is not limited to this, and may be dimmed using an ND filter.
(2) In the present embodiment, the half mirror 10 jumps up and retracts from the optical path of the subject light. However, the present invention is not limited to this, and the object may be retracted by a behavior such as a slide.
(3) In this embodiment, the normal sensitivity is ISO 200, 400, 800, 1600 and the low sensitivity is ISO 100. However, the present invention is not limited to this. For example, when ISO 200, 280, 400, 560, 800, 1100, and 1600 are used as the 1/2 step, ISO 100 and 140 are possible when the half mirror has a 50% light reduction rate. Further, the light attenuation rate is not limited to 50%, and may be more or less.
In addition, although embodiment and a deformation | transformation form can also be used in combination suitably, detailed description is abbreviate | omitted. Further, the present invention is not limited to the embodiment described above.

  1: camera, 7: finder, 10: half mirror, 15: CCD, 31: main control unit, 32: image control unit, 33: image memory, 44: adjustment unit, 45: correction unit

Claims (6)

An imaging unit for imaging light from the taking lens;
A dimming means capable of moving between an advancing position intersecting an optical path from the photographing lens to the imaging unit and a retracted position deviating from the optical path;
Storage means for storing optical characteristics of light transmitted through the dimming means;
Correction means for correcting the image picked up by the image pickup unit with the optical characteristics stored in the storage means;
A camera comprising: The camera according to claim 1,
When the dimming means is a half mirror, and the half mirror is located at an advancing position that intersects the optical path from the photographing lens to the imaging unit, the half light mirror reflects an object light to an optical viewfinder provided in the camera. Providing a visible image,
Camera characterized by. The camera according to claim 1 or 2,
The optical characteristic is color unevenness in light incident on the camera, transmitted through the dimming means, and imaged by the imaging unit;
Camera characterized by. The camera according to any one of claims 1 to 3,
A plurality of correction values are stored corresponding to the color temperature of the incident light;
Camera characterized by. The camera according to claim 4,
When the color temperature of the subject light is other than the color temperature at which the optical characteristic is stored, the optical characteristic corresponding to the subject light is obtained by calculation from the color temperature at which the optical characteristic is stored;
Camera characterized by. The camera according to any one of claims 1 to 5,
When the sensitivity of the imaging unit is set to be equal to or higher than the first sensitivity, the dimming means is retracted from the course at the time of shooting,
When the sensitivity of the imaging unit is set to a sensitivity smaller than the first sensitivity, shooting is performed with the dimming means being advanced in the course of shooting,
Camera characterized by.

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