JP2016142776A - Imaging device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an imaging device that does not increase a space and costs, further causes a subject image not to disappear due to a rotating operation of a main mirror, and is not affected by reversely incident light upon a finder in metering light.SOLUTION: An imaging device includes a light metering control system in a light metering mechanism via a penta prism, and is configured to: implement detection of presence or absence of a possibility that reversely incident light from an eyepiece lens affects light metering; when it is determined that the possibility of an influence due to the reversely incident light is present, compare a difference between an output of a light metering device and an output of a focus detection device with a prescribed value; when the difference is equal to or more than the prescribed value as a result of the output comparison, determine that the influence of the reversely incident light from the eyepiece lens on a light metering value is present; and correct the output of the light metering device using the output of the focus detection device. The determination of the presence or absence of the possibility that the reversely incident light from the eyepiece lens affects the light metering is implemented based on an output distribution of the light metering device.SELECTED DRAWING: Figure 6

Description

  The present invention relates to an imaging apparatus, and more particularly to photometric control of a single-lens reflex camera.

  Conventionally, in a single-lens reflex camera, there is a problem that reverse incident light from the viewfinder affects photometry, and the photometry performance is deteriorated. Various countermeasures have been proposed for the influence of reverse incident light on photometry. As one of the countermeasures, there is an imaging device that physically shields the viewfinder by providing a shutter. Therefore, it is necessary to provide a shutter in the viewfinder, which causes problems such as insufficient space and increased costs.

  Therefore, Patent Document 1 discloses a method for correcting reverse incident light by using two photometric devices, that is, a photometric device that performs photometric measurement of a photographic lens light beam and an auxiliary photometric device that mainly performs finder reverse incident light metering. . Further, in Patent Document 2, whether or not the reverse incident light metering operation is possible depending on the operation mode of the imaging device in an imaging device performing a reverse incident light metering operation in which the main mirror is raised and the photometry device measures the influence of the reverse incident light. And detecting the eyepiece state and performing the reverse light metering operation only when it is not in the eyepiece state.

Japanese Patent Laid-Open No. 01-304433 JP 2008-209552 A

  However, the prior art disclosed in the above-mentioned Patent Document 1 requires two photometric devices for photographing lens luminous flux and reverse incident light. Therefore, a space for installing a new photometric device to the conventional photometric device is required. It is necessary to secure it, and the cost is increased by using two photometric devices.

  In the prior art disclosed in Patent Document 2 described above, the main mirror must be moved up and down during the reverse light metering operation, and the subject cannot be observed when the main mirror is rotated. In addition, it is determined whether or not the reverse light metering operation is performed based on the detection of the eyepiece state, but when the photographer wears glasses or the like even in the eyepiece state, the light reflected on the eyeglasses is measured as back incident light. There is a possibility that it may affect, and accurate photometry may not be possible.

  SUMMARY OF THE INVENTION An object of the present invention is to provide an imaging apparatus that does not increase space and cost, and that is not affected by the finder reverse incident light at the time of photometry without losing the subject image due to the rotation of the main mirror.

  In order to achieve the above object, the imaging apparatus of the present invention has a photometry control system in a photometry mechanism via a pentaprism, and detects whether there is a possibility that reverse incident light from an eyepiece lens has an effect on photometry. If the difference between the output of the photometric device and the output of the focus detection device is compared and the output is compared, the difference is greater than a predetermined value. Then, it is judged that there is an influence on the photometric value of reverse incident light from the eyepiece lens, and the output of the photometric device is corrected using the output of the focus detection device.

  In addition, it is characterized in that the determination of whether or not the reverse incident light from the eyepiece lens has an influence on the photometry is made based on the output distribution of the photometry device.

  According to the present invention, it is possible to provide an imaging apparatus capable of correcting the influence of finder reverse incident light on photometry without disturbing subject observation.

Schematic of the imaging apparatus according to the present invention when the mirror is down Schematic of the image pickup apparatus according to the present invention at the time of mirror up The block diagram of the imaging device concerning the present invention Schematic showing the optical path of finder reverse incident light Schematic showing the difference in light intensity of the finder reverse incident light Imaging sequence of imaging apparatus according to the present invention Schematic diagram when a photometric area, block division, and line sensor are virtually placed in the viewfinder field

  Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings.

  1 and 2 are schematic views of an imaging apparatus according to an embodiment of the present invention.

  In FIG. 1, reference numeral 100 denotes an imaging apparatus main body. Reference numeral 101 denotes a CPU which controls the imaging apparatus 100. Reference numeral 102 denotes an interchangeable photographic lens body, which has a focus lens 103 that moves in the optical axis direction during focus adjustment, a zoom lens (not shown) that moves in the optical axis direction during zooming, lens information such as a diaphragm 104 and a lens ID. And a lens CPU 105 that controls the focus lens 103 and the diaphragm 104 based on a command from the CPU 101 of the imaging apparatus 100. In accordance with a command from the lens CPU 105, focus adjustment is performed by driving the focus lens 103, and exposure is controlled by driving the diaphragm 104. Reference numeral 106 denotes an image pickup element made of CMOS (Complementary Metal Oxide Semiconductor), which has an unillustrated image pickup pixel group made up of pixels used for acquiring image signals for image pickup, with RGB color filters provided on the light receiving surface.

  Reference numeral 109 denotes a main mirror, which is configured as a semi-transmissive mirror. Reference numeral 112 denotes a focusing screen, which is disposed on an imaging plane equivalent to the imaging plane of the image sensor 106 on which the subject image transmitted through the photographing lens 102 is formed. Reference numeral 118 denotes a subject optical path, and the light beam that has passed through the photographing lens 102 is reflected by the main mirror 109 and is primarily imaged on the focusing screen 112. The pentaprism 113 changes the subject optical path 118 and corrects the subject image formed on the focusing screen 112 to an erect image. The eyepiece 114 allows the photographer 115 to observe the subject image formed on the focusing screen 112.

  Reference numeral 110 denotes a sub-mirror, and the subject light flux that has passed through the main mirror 109 that is a half mirror is guided to the focus detection device 111 by the sub-mirror 110. The focus detection device 111 includes a pair of line CCD sensors for focus detection, and a known phase difference detection type focus detection operation is performed using the sensor output. Further, as will be described later, in this embodiment, the luminance of the subject is also measured using the output of the line sensor. Reference numeral 107 denotes a photometric device. Of the luminous flux from the focusing screen 112, a luminous flux that diffuses at a predetermined angle is imaged onto the photometric device 107 by the photometric lens 117 via the pentaprism 113, and the photometric device 107 detects the subject. The block is divided into a predetermined number of blocks, the brightness of each block is detected, and the CPU 101 performs a desired calculation to determine the exposure of the imaging apparatus.

  FIG. 2 is a diagram in which the main mirror 109 and the sub mirror 110 are retracted from the subject optical path 118 that has passed through the photographing lens 102.

  When the photographer 115 presses the release switch 205 in FIG. 3 or sets the live view state by operating the image capturing apparatus 100 when performing photographing, the main mirror 109 performs subject light flux passing through the photographing lens 102 from the viewfinder observation position. Is automatically retracted out of the subject optical path 118, and the subject image from the photographing lens 102 can be exposed to the image sensor 106.

  The focal plane shutter (hereinafter referred to as shutter) 108 includes a magnet MG-1 that opens the front curtain when energized, and a magnet MG-2 that closes the rear curtain of the shutter 108 when energized. The light flux of the subject focused by the photographing lens 102 is controlled by controlling the time from the first curtain running of the shutter 108 until the rear curtain starts running, and the image sensor 106 performs photoelectric conversion processing as a subject image. Is done. The image data after the photoelectric conversion process is recorded on a recording medium and displayed as an image on the external display device 116. The external display device 116 displays the image of the subject exposed to the image sensor 106 in real time when the imaging device 100 is in the live view state.

  FIG. 3 is a block diagram showing an electrical configuration of the imaging apparatus according to the embodiment of the present invention. The CPU 101 includes an EEPROM 101a that is a nonvolatile memory, performs processing based on a control program, transmits the processing result to each connected unit, and controls the entire imaging apparatus 101.

  An image sensor control unit 201 includes a timing generator (not shown), a noise removal / gain processing circuit, an A / D conversion circuit, and a pixel thinning processing circuit. The timing generator supplies a transfer clock signal and a shutter signal to the image sensor control unit 201. The noise removal / gain processing circuit performs noise removal and gain processing on the analog signal output from the image sensor 106. The A / D conversion circuit converts an analog signal into a 10-bit digital signal. The pixel thinning processing circuit performs pixel thinning processing in accordance with the resolution conversion instruction from the CPU 101.

  A display control unit 204 displays on the external display device 116 images captured by the image sensor 106 and subjected to vertical and horizontal thinning processing by the image sensor control unit 201. The image processing unit 202 performs image processing (gamma conversion, color space conversion, white balance, automatic exposure, flash correction, etc.) on the 10-bit digital signal output from the image sensor control unit 201, and YUV (4: 2: 2) Output as a format 8-bit digital signal.

  The focus detection device control unit 203 A / D converts the voltage obtained from the line CCD sensor of the focus detection device 111 and sends it to the CPU 101. The focus detection device control unit 203 also controls the light amount accumulation time and auto gain control of the line CCD sensor based on an instruction from the CPU 101. The battery 207 is configured as a rechargeable secondary battery (or dry battery).

  The DC / DC converter 206 receives a power supply from the battery 207, generates a plurality of power supplies by boosting and regulating, and supplies a power supply of a necessary voltage to the CPU 101 and each element. The DC / DC converter 207 can control the start and stop of each voltage supply by a control signal from the CPU 101. The photometric device control unit 208 A / D converts the voltage obtained from the photometric device 107 and sends it to the CPU 101.

  Here, the finder reverse incident light will be described with reference to FIG. In FIG. 4, the solid line arrow indicates the optical path of the finder reverse incident light. The light enters the inside of the pentaprism 113 through the eyepiece lens 114, is reflected by the pentaprism 113, and reaches the focusing screen 112.

  An optical path that reaches the photometry device 107 after reaching the focusing screen 112 is indicated by a broken-line arrow. The light that has reached the focusing screen 112 is reflected and diffused by the mat surface of the focusing screen 112, is reflected again by the pentaprism 113, and forms an image on the photometric device 107 through the photometric lens 117. As a result, the luminance on the focusing screen 112 changes due to the overlapped light on the subject image from the photographic lens 102 that is imaged on the focusing screen 112, and the subject luminance is accurately measured. It becomes difficult.

  FIG. 5 shows the reflected light path and the reflected intensity at each position of the focusing screen 112 when light of uniform luminance is received from the finder. Since the central light beam of the photometric device 107 has an inclination with respect to the finder central light beam, the amount of light on the focusing screen 112 changes in the left-right direction in FIG. 5 (vertical direction when looking through the viewfinder). The amount of reflected light becomes stronger as the angle of the reflected light becomes closer to the focusing screen 112, and the amount of reflected light becomes weaker as the angle becomes shallower. Therefore, the left side of FIG. 5 (upper viewfinder field) has a strong reflected light, that is, the influence of reverse incident light increases, and as it goes to the right side (lower viewfinder field), the influence of reverse incident light decreases.

  Next, a still image shooting operation sequence at the time of photometry control by AE through the pentaprism of the imaging apparatus according to the present invention will be described with reference to FIG.

  In S101, it is determined whether or not the release SW 205 is pushed in one step by the photographer 105 (hereinafter referred to as SW1ON). If SW1 is not ON, the imaging apparatus is in a standby state. If SW1 is ON, the process proceeds to S102.

  In S102, a focus detection operation using the focus detection device 111 is started, and the subject is focused in S103.

  After focusing in S103, a photometric operation using the photometric device 107 is started in S104, and the luminance of the subject imaged on the focusing screen 112 is acquired as a photometric value in S105.

  In S106, the presence / absence of an influence due to reverse incident light is detected. As described above, the influence of the reverse incident light tends to increase the influence of the upper part of the viewfinder field. In addition, the range of influence of back incident light is limited by the eyepiece 114 and the holder shape that holds them. FIG. 7 is a schematic diagram when the photometry area of the photometry device 107 and the block division and the line sensor of the focus detection device 111 are virtually arranged on the finder.

  In FIG. 7, reference numeral 701 denotes a visual field region when looking through the viewfinder. Reference numerals 801 to 812 denote line sensor arrangements of the focus detection device 111, and each line sensor does not observe the entire visual field area 701 but is discretely arranged in a part of the visual field area 701. Reference numeral 702 denotes a photometry area of the photometry apparatus 107. In this embodiment, the photometry area 702 is divided into 9 × 7 63 blocks, and the photometry apparatus 107 performs photometry in each block. Is arranged. In addition, a shaded area in the photometry area 702 and an area 703 indicate blocks to which the influence of reverse incident light is exerted. The difference between the average photometric value of the photometric area 702 excluding the area 703 and the average photometric value of the area 703 is taken and compared with a predetermined threshold value. Here, if the average value of the region 703 is higher than the other average values and exceeds the threshold value, it is determined that there is a possibility of being affected by the reverse incident light, and the process proceeds to S107. On the other hand, if it is less than or equal to the threshold value, it is determined that there is no influence of reverse incident light and the process proceeds to S112.

  If it is determined in S106 that there is a possibility of being affected by the reverse incident light, the subject is measured using the focus detection device 111 in S107. The line sensors 801 to 812 of the focus detection device 111 are photodiodes, which control the gain and accumulation time, measure the luminance distribution of the subject image, perform the AF of the phase difference detection method, and calculate the subject luminance. Is possible. In view of this, the output of the focus detection device 111 is provided to the output of the photometry device 107 by providing, as table-type data, the correlation between the gain at each subject luminance of the focus detection device 111 and the output during the accumulation time and the output of the photometry device 107. It can be converted into a photometric value as an output. In addition, only the line sensors arranged in the region 703, in this embodiment, 802, 804, 805, and 810, are detected, and the detection time can be shortened by not using unnecessary line sensors.

  In S108, the difference between the photometric value of the subject luminance in the focus detection device 111 detected in S107 is calculated from the photometric value of the subject luminance in the photometric device 107 calculated in S105. At this time, the difference between the output of each photometric block of the photometric device 107 and the output of the corresponding line sensor is calculated for each block. In the case of FIG. 7, the outputs of the four line sensors 802, 804, 805, and 810 in the region 703 are calculated, and the blocks 703a, 703b, 703c, and 703d corresponding to the four line sensors 800 are crossed (hatched lines are crossed). The difference from the output of each block is calculated.

  In S109, the difference in each block calculated in S108 is compared with a predetermined threshold value provided in advance for each block, and the influence of back incident light is determined. Here, even if one block is equal to or greater than a predetermined threshold, it is determined that there is a possibility of being affected by back incident light. Basically, when there is an influence of reverse incident light, the photometric value of the photometric device 107 is larger than the photometric value of the focus detecting device 111, so S105> S107, and the predetermined threshold value> 0. If it is determined in S109 that there is no influence of back light, the process proceeds to S112, and if it is determined that there is an influence of back light, the process proceeds to S110.

  In S110, the photometric value of the region 703 is corrected based on the photometric value of the focus detection device 111 acquired in photometry S107 which is affected by the reverse incident light. Each of the blocks 703a uses a photometric value obtained from the corresponding line sensor 800. In other blocks in the region 703, the corrected photometric value of the block 703a and the photometric values of the surrounding blocks are complemented linearly or nonlinearly, The photometric value of each block in the area 703 is calculated.

  In S111, the photometric value calculated in S110 is applied to the block in the region 703 with respect to the photometric value of the photometric device 107 acquired in S105.

  In S <b> 112, an exposure calculation corresponding to the photometric mode preset by the photographer 115 is performed in the CPU 101 based on the obtained photometric value. In S113, the exposure is determined from the calculation result in S112. In step S114, it is determined whether the release SW 205 is turned on. If the release SW 205 is not turned on, the camera is in a standby state until the release SW 205 is turned on.

  As mentioned above, although preferable embodiment of this invention was described, this invention is not limited to these embodiment, A various deformation | transformation and change are possible within the range of the summary.

100 imaging device, 101 CPU, 102 photographing lens, 107 photometric device,
111 focus detection device, 114 eyepiece, 203 focus detection device control unit,
208 photometric device control unit, 701 field of view range, 702 photometric range,
801 Line sensor

Claims (2)

It has a photometric control system in the photometric mechanism via the pentaprism (113), detects whether there is a possibility that the reverse incident light from the eyepiece lens (114) has an influence on the photometry, and can be influenced by the reverse incident light If the difference between the output of the photometry device (107) and the output of the focus detection device (111) is compared and the output comparison is made, if the difference is greater than a predetermined value, The imaging apparatus is characterized in that it determines that there is an influence on the photometric value of reverse incident light and corrects the output of the photometric apparatus (107) using the output of the focus detection apparatus (111). 2. The image pickup apparatus according to claim 1, wherein the presence / absence of the possibility that the reverse incident light from the eyepiece lens (114) has an influence on the photometry is determined based on an output distribution of the photometry apparatus (107). .