JP5906577B2 - Photometric device and camera - Google Patents

Description

  The present invention relates to a photometric device and a camera.

  A photometric device using a storage type light receiving element is known (see Patent Document 1). In general, the photometric device is controlled to accumulate by AGC (AUTO GAIN CONTROL) or the like so that the output signal value from the light receiving element becomes a predetermined level. If the output signal level after accumulation is low and not suitable for photometric calculation, the accumulation time is changed to a longer time and the accumulation operation is repeated.

Japanese Patent Laid-Open No. 9-160088

  However, in an extremely dark environment, if the luminance of the subject changes in the dark environment, there is a problem that it is not sufficient to extend the accumulation time with AGC. In particular, there is a problem that it is likely to be a problem when it is desired to perform photometry at LV0 or less, and the release time lag becomes large.

The photometric device according to the present invention includes a first photometric mode in which photometry is performed using an output signal from a light receiving element, and a second photometric mode for performing photometry in an environment darker than the first photometric mode using an output signal from the light receiving element. And a light receiving element after the output signal when the maximum value of the output signal is larger than the first value when the setting unit is set to the first photometry mode or the second photometry mode. When the setting unit is set to the first photometry mode and the maximum value of the output signal is smaller than the first value , the maximum value of the output signal is smaller than the first value. greater than the second value, performs photometric calculation using the output signal when the minimum value of the output signal is less than the third value smaller than the second value, setting unit is set to the second metering mode The maximum value of the output signal is smaller than the first value There case, greater than the maximum value of the second value smaller than the fourth value of the output signal by using an output signal when the minimum value of the output signal is less than the smaller fifth value than the third value and a line intends calculation unit photometric operation.
A camera according to the present invention includes the photometric device described above.

  According to the present invention, it is possible to provide a photometric device capable of suitable photometry even in a dark environment.

It is a figure explaining the principal part structure of the single-lens reflex electronic camera carrying the photometry apparatus by one embodiment of this invention. It is a block diagram explaining the photometry part of an electronic camera. It is a flowchart explaining the flow of imaging | photography process. It is a flowchart explaining the flow of the photometry process which a microcomputer performs. It is a flowchart explaining the flow of effectiveness determination processing.

  Hereinafter, embodiments for carrying out the present invention will be described with reference to the drawings. FIG. 1 is a diagram for explaining a main configuration of a single-lens reflex electronic camera equipped with a photometric device according to an embodiment of the present invention. In FIG. 1, a lens barrel constituting a photographic lens 1 that can be attached to and detached from the camera body 4 is attached.

  Light from the subject enters the camera body 4 via the photographing optical system 2 and the diaphragm 3. The subject light incident on the camera body 4 is bent toward the upper finder by a transflective quick return mirror (hereinafter referred to as a main mirror) 5 in the mirror-down state illustrated in FIG. Proceed toward. Further, the subject light transmitted through the main mirror 5 is bent downward by the sub mirror 14 and guided to the focus detection sensor 15.

  The subject light beam incident on the screen 6 forms an image on the diffusing surface 6 a by the photographing optical system 2. The light beam transmitted through the screen 6 is further incident on the pentaprism 8 along the optical axis 22 of the finder optical system. The pentaprism 8 guides the incident subject light to the finder lens 9. The photographer observes the subject image by the finder through the finder lens 9 from the eyepiece 10.

  A part of the light beam that has passed through the screen 6 proceeds in the direction of the photometric optical system optical axis 23 inclined from the optical axis 22 of the finder optical system, and is bent upward by the reflecting surface 11 a of the triangular prism 11. This light beam is re-imaged on the light receiving surface of the photometric sensor 13 through a photometric aperture and a photometric lens 12 (not shown).

  After the release, the main mirror 5 rotates upward, and all subject light is guided to the image sensor 17 via the mechanical shutter 16 that is driven to open, and an object image is formed on the image pickup surface. The image sensor 17 captures a subject image formed on the imaging surface, and outputs a photoelectric conversion signal corresponding to the brightness of the subject image. When the imaging is completed, the mechanical shutter 16 is driven to close and the main mirror 5 returns to the down position.

  In the electronic camera described above, the photometric sensor 13 is constituted by a CMOS image sensor or the like provided with a plurality of photoelectric conversion elements corresponding to pixels. The photoelectric conversion element accumulates signal charges according to the intensity of light. The accumulated signal from the photometric sensor 13 is used not only for photometric calculation but also for TTL (through the lens) dimming calculation, face detection processing, scene recognition processing, and the like. For this reason, a color filter 13a arranged in a Bayer arrangement corresponding to the pixel position is provided on the light receiving surface of the photometric sensor 13 so that color information can be obtained from an image obtained based on the accumulated signal from the photometric sensor 13. .

<Configuration of metering unit>
Since the present embodiment has a feature in the photometry unit of the electronic camera, the following description will be focused on the photometry unit. FIG. 2 is a block diagram illustrating a photometry unit of the electronic camera. The photometric unit includes photometric optical systems 11 and 12, a photometric sensor 13, an A / D conversion unit 51, a signal processing unit 52, and a microcomputer 53. The microcomputer 53 receives a release operation signal indicating that the release button 54 has been pressed, and a signal instructing switching from the mode setting member 55 to the “low luminance shooting mode” or to the “normal mode”. Is done. The “low luminance shooting mode” is a mode in which the photometric process is performed in a dark environment (for example, LV0 or lower) compared to the “normal mode”.

  The photometry modes in the present embodiment include, for example, “division photometry mode”, “center-weight photometry mode”, and “spot photometry mode”. The “divided photometry mode” is a mode in which the photographing screen is divided into a plurality of brightness values, a plurality of brightness values are calculated, and an exposure calculation is performed based on the plurality of brightness values. The “center-weighted metering mode” is a mode for performing an exposure calculation based on a luminance value with an emphasis on the center of the shooting screen. The “spot metering mode” is a mode in which an exposure calculation is performed based on a luminance value within a predetermined narrow range in the shooting screen. In the present embodiment, the microcomputer 53 switches the photometry mode in response to an operation signal from a photometry mode switching operation member (not shown), and in the case of the “low brightness photographing mode”, the operation signal from the photometry mode switching operation member is used. Regardless, it automatically switches to the “split metering mode”.

  The microcomputer 53 performs calculations related to photometry and controls the accumulation operation for the photometric sensor 13. The accumulation operation is controlled by changing at least one of accumulation time and amplification gain. The amplification gain refers to the gain of an amplification amplifier (not shown) provided in the photometric sensor 13.

  The photometric light beams that have passed through the photometric optical systems 11 and 12 form a subject image on the photometric sensor 13. The photometric sensor 13 outputs a photoelectric conversion signal received through the color filter 13a (FIG. 1). The color filter 13a is configured by, for example, R, G, and B color filters disposed at the pixel positions of the photometric sensor 13. A photoelectric conversion signal corresponding to light of the R color component is output from the pixel received through the R color filter, and a photoelectric conversion signal corresponding to light of the G color component is output from the pixel received through the G color filter, A photoelectric conversion signal corresponding to the light of the B color component is output from the pixel received through the B color filter.

  The photometric sensor 13 receives a driving clock signal, a signal for controlling the accumulation time, and a gain control signal for controlling the amplification gain from a photometric sensor control unit 531 included in the microcomputer 53. The photometric sensor 13 outputs the accumulated charge signal to the A / D converter 51. The A / D conversion unit 51 obtains a photometric digital signal for each pixel by performing A / D conversion (analog signal → digital signal conversion) on the input signal. The signal processing unit 52 performs a clamping process on the photometric digital signal. The clamping process refers to clamping so that output data from a light-shielded pixel (referred to as optical black) provided in advance in the photometric sensor 13 becomes a so-called black level (reference of photometric output data).

  The accumulation time / gain calculation unit 532 calculates the accumulation time and amplification gain for the next accumulation of the photometric sensor 13 based on the photometric output data output from the signal processing unit 52. The validity determination unit 533 determines the validity of the photometric output data output from the signal processing unit 52. Based on the photometric output data output from the signal processing unit 52, the target level and validity determination level calculating unit 534 sets the target level of the photometric output data to be obtained by the next accumulation and the photometric output after the next accumulation. Each determination level used for determining the validity of the data is calculated. The photometric sensor control unit 531 is based on the control signal (described above) based on the accumulation time, the calculation result by the gain calculation unit 532, the determination result by the validity determination unit 533, and the calculation result by the target level and validity determination level calculation unit 534. A driving clock signal, an accumulation time control signal, and a gain control signal) are sent to the photometric sensor 13.

  With the above configuration, the photometric sensor control unit 531 determines the accumulation time and amplification gain of the photometric sensor 13 so that the maximum value of the photometric output data after the next charge accumulation approaches the target value Vagc. The photometric sensor 13 is feedback controlled so that the next accumulation is performed with the amplification gain. The target value Vagc is set to a value lower than the upper limit level Vov of the dynamic range. In this description, the range in which the output value of the photometric sensor 13 has linearity is called a dynamic range, the upper limit of the dynamic range is the upper limit level Vov, and the lower limit of the dynamic range is the lower limit level Vun.

  The photometric output data obtained by the above accumulation control is used for photometric calculation. The Bv value calculation / exposure calculation unit 535 calculates a Bv value based on the photometric output data determined to be valid by the validity determination unit 533, and performs a predetermined exposure calculation according to the Bv value. The photometry area setting unit 536 sets an area used for photometry calculation according to the photometry mode. This photometric area corresponds to the range in which the Bv value calculation / exposure calculation unit 535 calculates the luminance value in the shooting screen. That is, the Bv value calculation / exposure calculation unit 535 performs the above calculation using photometry output data from pixels corresponding to the area set by the photometry area setting unit 536.

  The aperture control unit 561 and the shutter control unit 562 constitute an exposure control unit 56. The aperture control unit 561 controls the aperture 3 during shooting based on the Bv value calculation and the exposure calculation result by the exposure calculation unit 535. The shutter control unit 562 controls the mechanical shutter 16 during shooting based on the Bv value calculation and the exposure calculation result by the exposure calculation unit 535.

<Shooting process>
FIG. 3 is a flowchart for explaining a flow of photographing processing performed by a photographing control circuit (not shown) of the electronic camera. The light metering unit performs a light metering process (S12) in the photographing process. In step S11 of FIG. 3, the imaging control circuit determines whether or not the release button 54 has been pressed halfway. When the half-press operation is performed, the imaging control circuit makes a positive determination in step S11 and proceeds to step S12. When the half-press operation is not performed, the imaging control circuit makes a negative determination in step S11 and proceeds to step S21.

  In step S12, the imaging control circuit sends an instruction to the microcomputer 53 to perform photometry processing and proceeds to step S13. Details of the photometric processing will be described later. In step S13, the imaging control circuit performs a known AF process using the detection signal from the focus detection sensor 15, and proceeds to step S14. In step S14, the imaging control circuit determines whether or not the release button 54 has been fully pressed. The imaging control circuit makes an affirmative determination in step S14 when the full-press operation is performed, and proceeds to step S15. If the full-press operation is not performed, the negative determination is made in step S14 and the process returns to step S11.

  In step S15, the imaging control circuit sends an instruction to a sequence control device (not shown), starts up driving of the main mirror 5, and proceeds to step S16. In step S16, the imaging control circuit initializes the image sensor 17 and proceeds to step S17. In step S <b> 17, the imaging control circuit causes the image sensor 17 to accumulate charge for imaging for a predetermined time. It should be noted that the aperture 3 and the mechanical shutter 16 are driven by an exposure control unit 56 constituting a sequence control device (not shown) so as to obtain a controlled exposure calculated by an exposure calculation using the photometric processing result. The imaging control circuit instructs the readout of the accumulated signal from the image sensor 17 and proceeds to step S18.

  In step S18, the imaging control circuit sends an instruction to a sequence control device (not shown) to start down driving of the main mirror 5 and then proceeds to step S19. In step S19, the imaging control circuit performs predetermined image processing on the photoelectric conversion signals constituting the image, and proceeds to step S20. In step S20, the imaging control circuit records the image-processed data on a recording medium (not shown), and ends the imaging process shown in FIG.

  In step S21, which proceeds with a negative determination in step S11, the imaging control circuit determines whether or not the timer has expired. The imaging control circuit makes an affirmative decision in step S21 when a predetermined time has elapsed in the no-operation state, and ends the process of FIG. On the other hand, if the predetermined time has not elapsed, the imaging control circuit makes a negative determination in step S21 and returns to step S11.

<Photometric processing>
FIG. 4 is a flowchart for explaining the flow of photometric processing performed by the microcomputer 53. The photometric process in FIG. 4 corresponds to step S12 in FIG. In step S101 of FIG. 4, the microcomputer 53 determines whether or not the “low luminance shooting mode” is set. The microcomputer 53 makes an affirmative decision in step S101 when a signal instructing switching from the mode setting member 55 to the “low luminance photographing mode” is input, sets the “low luminance photographing mode”, and then proceeds to step S102. move on. The microcomputer 53 makes a negative determination in step S101 when the signal for instructing the switching to the “low brightness photographing mode” is not input from the mode setting member 55, sets the “normal mode”, and proceeds to step S111. .

  When the process proceeds to step S111, it is “normal mode” (not “low luminance shooting mode”). In step S111, the microcomputer 53 returns the photometry mode automatically set in the “low brightness photographing mode” to the original photometry mode (that is, the photometry mode corresponding to the operation signal from the photometry mode switching operation member (not shown)). Then, the process proceeds to step S112. In step S112, the target level / effectiveness determination level calculation unit 534 of the microcomputer 53 sets the effective determination level Vok and the lower limit level Vun as determination thresholds used for the effectiveness determination as follows, and proceeds to step S104. . The validity determination level Vok and the lower limit level Vun are respectively used for the validity determination performed in step S107 in the “normal mode”.

  The photometric device of this embodiment is configured such that, for example, when EV0 is stored with an accumulation time int = 100 msec and an amplification gain = 4, the photometric output data is 25 LSB (where LSB is the least significant bit). It shall be. Then, the validity determination level Vok in the “normal mode” is set to 200 LSB. Further, the lower limit level Vun in the “normal mode” is set to 10 LSB. The value of the lower limit level Vun is determined so that the photometric output data of the photometric sensor 13 when accumulated in the longest accumulation time (accumulation time upper limit value described later) in the “normal mode” satisfies the linear characteristics described above.

  When the process proceeds to step S102, the “low luminance shooting mode” is set. In step S102, the microcomputer 53 sets the “division metering mode” and proceeds to step S103. In step S103, the target level / effectiveness determination level calculation unit 534 of the microcomputer 53 sets the effective determination level VokN and the lower limit level VunN as determination thresholds used for the effectiveness determination as follows, and proceeds to step S104. Each of the validity determination level VokN and the lower limit level VunN is used for the validity determination performed in step S107 in the “low luminance shooting mode”.

In the present embodiment, the effective determination level VokN in the “low luminance shooting mode” is calculated by the following equation (1).
VokN = Vok−Vx (1)
However, Vok is an effective determination level in the “normal mode”. Vx is a predetermined value, and is determined according to the longest accumulation time (accumulation time upper limit value to be described later) in the “normal mode” and the “low luminance imaging mode”. In this example, Vx = 150 LSB.

In the present embodiment, the lower limit level VunN in the “low luminance shooting mode” is calculated by the following equation (2).
VunN = Vun−Vy (2)
However, Vun is the lower limit level in the “normal mode”. Vy is a predetermined value, and is determined according to the longest accumulation time (accumulation time upper limit value to be described later) in the “normal mode” and the “low luminance shooting mode”. In this example, Vy = 8 LSB.

  In step S104, the photometric sensor control unit 531 of the microcomputer 53 causes the photometric sensor 13 to perform an accumulation operation and proceeds to step S105. In step S105, the microcomputer 53 inputs the photometric output data read from the photometric sensor 13 via the signal processing unit 52, and proceeds to step S106.

In step S106, the microcomputer 53 calculates the next accumulation time int ′ and the next amplification gain, and proceeds to step S107. The next accumulation time int ′ is calculated by the accumulation time / gain calculation unit 532 using the following equation (3). In this description, the next amplification gain is four times.
int '= int × Vagc / Vomax (3)
Where int is the previous accumulation time. Vagc is a target value of the maximum value of the photometric output data after the next charge accumulation, for example, 720 LSB. Vomax is the maximum value of the photometric output data obtained by the previous accumulation. For example, in the case where the maximum value Vomax of the previous photometric output data with the accumulation time int = 100 msec was 600 LSB, int ′ = 100 × 720/600 = 120 msec. In the case of the first accumulation, since there is no previous condition or previous photometric output data, it is performed under a predetermined initial condition (for example, accumulation time int = 100 msec, amplification gain 4 times).

  The photometric sensor control unit 531 of this embodiment sets an upper limit of the accumulation time to the accumulation time int ′ set for the photometric sensor 13. In the “normal mode”, the upper limit value of the accumulation time is set to 100 msec, for example, and even when a value exceeding 100 msec is calculated by the above equation (3), the longest accumulation time int ′ is suppressed to 100 msec. In the “low luminance shooting mode”, the upper limit of the accumulation time is set to 400 msec, for example, and the maximum accumulation time int ′ is suppressed to 400 msec even when a value exceeding 400 msec is calculated by the above equation (3).

  In step S107, the validity determination unit 533 of the microcomputer 53 performs the photometry output data validity determination process obtained by the accumulation in step S104, and the process proceeds to step S108. Details of the validity determination process will be described later.

  In step S108, the microcomputer 53 determines whether the photometric output data is valid. If the microcomputer 53 determines that it is valid in step S107, the microcomputer 53 makes a positive determination in step S108 and proceeds to step S109. If the microcomputer 53 does not determine that it is valid in step S107, it makes a negative determination in step S108 and returns to step S104. When returning to step S104, the accumulation operation is performed again without using the photometric output data obtained in the accumulation in step S104 for the Bv value calculation (S109).

  In step S109, the Bv value calculation / exposure calculation unit 535 of the microcomputer 53 calculates the Bv value based on the photometric output data determined to be valid, and proceeds to step S110. In step S110, the Bv value calculation / exposure calculation unit 535 of the microcomputer 53 performs a predetermined exposure calculation according to the Bv value, and ends the process of FIG.

<Effectiveness determination process>
FIG. 5 is a flowchart for explaining the flow of the validity determination process performed by the validity determination unit 533 of the microcomputer 53. In step S1071, the validity determination unit 533 that performs the validity determination process in step S107 in FIG. 4 calculates the maximum value Vomax and the minimum value Vomin of the photometric output data obtained by the accumulation in step S104, and proceeds to step S1072. . Note that the maximum value Vomax is the same as the value used in step S106.

  In step S1072, the validity determination unit 533 determines whether the maximum value Vomax is smaller than the upper limit level Vov. The validity determination unit 533 makes an affirmative decision in step S1072 if Vomax <Vov is established, and proceeds to step S1073. The process proceeds to step S1073 when the output data of the photometric sensor 13 has not overflowed. If Vomax <Vov does not hold, the validity determination unit 533 makes a negative determination in step S1072 and ends the process of FIG.

  In step S1073, the validity determination unit 533 determines whether or not the minimum value Vomin is smaller than the lower limit level Vun. The validity determination unit 533 makes an affirmative determination in step S1073 when Vomin <Vun is established, and proceeds to step S1075. In the case where Vomin <Vun is not established, the validity determination unit 533 makes a negative determination in step S1073 and proceeds to step S1074. The negative determination in step S1073 is a case where the output data of the photometric sensor 13 does not underflow.

  It should be noted that the validity determination unit 533 that performs the validity determination process in the “low luminance shooting mode” determines whether or not the minimum value Vomin is smaller than the lower limit level VunN in step S1073. The value of the lower limit level VunN is smaller than the lower limit level Vun in the “normal mode” as described above. Effectiveness determination section 533 makes an affirmative determination in step S1073 when Vomin <VunN is satisfied, and proceeds to step S1075. In the case where Vomin <VunN is not established, the validity determination unit 533 makes a negative determination in step S1073 and proceeds to step S1074.

  In step S1075, the validity determination unit 533 determines whether the maximum value Vomax is greater than the validity determination level Vok. The value of Vok is as described above. The validity determination unit 533 makes an affirmative determination in step S1075 when Vomax> Vok is satisfied, and proceeds to step S1074. When the determination in step S1075 is affirmative, the output data of the photometric sensor 13 includes underflow data, but there is data greater than the valid determination level Vok. If Vomax> Vok is not satisfied, the validity determination unit 533 makes a negative determination in step S1075 and ends the process of FIG.

  Note that the validity determination unit 533 that performs the validity determination process in the case of the “low luminance shooting mode” determines whether or not the maximum value Vomax is greater than the validity determination level VokN in step S1075. The value of the validity determination level VokN is a value smaller than the validity determination level Vok in the “normal mode” as described above. The validity determination unit 533 makes an affirmative determination in step S1075 if Vomax> VokN is satisfied, and proceeds to step S1074. When the determination in step S1075 is affirmative, the output data of the photometric sensor 13 includes underflow data, but there is data greater than the valid determination level VokN. If Vomax> VokN is not established, the validity determination unit 533 makes a negative determination in step S1075 and ends the process of FIG.

According to the embodiment described above, the following operational effects can be obtained.
(1) The photometric device of the electronic camera has an accumulation time for calculating the next accumulation time int ′ so that the photometric output data from the accumulation-type photometric sensor 13 approaches Vagc, a gain calculation unit 532, the photometric output data, and the lower limit A validity determination unit 533 that determines whether or not the photometric output data is valid based on a comparison between the level and an effective determination level that is greater than the lower limit level, and the photometric output data when the validity determination unit 533 makes a negative determination The photometric sensor control unit 531 that causes the photometric sensor 13 to perform the next accumulation with the accumulation time and the accumulation time calculated by the gain calculation unit 532 without performing photometric calculation, and the lower limit level in the low-luminance shooting mode from the value in the normal mode And a microcomputer 53 that controls the effectiveness determination unit 533 so as to be changed to a smaller value. Thereby, photometry can be appropriately performed in a dark environment such as LV0 or lower.

  In general, the photometric output data from the storage type photometric sensor 13 is small in a dark environment. Low-level metering output that could not be metered in normal mode by changing the lower limit level for comparison when determining whether metering output data is valid in low-luminance shooting modes such as at night The possibility that the data is used for the photometric calculation in the low brightness photographing mode is increased. In this way, it is possible to appropriately perform photometry in a dark environment.

(2) In the photometric device of (1) above, the microcomputer 53 further controls the validity determination unit 533 so that the validity determination level is changed to be smaller than the value in the normal mode in the low-luminance shooting mode. For example, photometry can be appropriately performed in a dark environment such as LV0 or lower. Although the photometric sensor output is kept linear by changing the effective judgment level used for comparison when judging whether photometric output data is valid in low-luminance shooting modes such as at night, etc. Therefore, the possibility of using low-level photometric output data that could not be photometrically calculated in the normal mode for photometric calculation in the low-luminance shooting mode is increased. This also increases the possibility of reducing the release time lag. In this way, it is possible to appropriately perform photometry in a dark environment.

Specifically, it is assumed that the next accumulation time calculation int ′ at a certain time point is 300 msec. Immediately before starting the accumulation of the photometric sensor 13 at 300 msec, the luminance of the subject becomes dark and becomes LV-1, and the maximum value Vomax of the photometric output data when accumulated in this state is 80 LSB, and the minimum value Vomin is 4 LSB. .
In this case, if the validity determination level Vok (for example, 200 LSB) and the lower limit level Vun (for example, 10 LSB) for “normal mode” are used, since it is Vomin <Vun and Vomax <Vok, it is not determined to be valid. However, by using the effective determination level VokN (for example, 50 LSB, the lower limit level VunN (for example, 2 LSB) for the “low luminance mode”, it is determined to be effective because Vomin> VunN and Vomax> VokN.
If it is not determined to be valid, the photometry output data is discarded and the process returns to step S104 to re-store the photometry sensor 13. If the control determines as described above, the data can be discarded. Don't waste time. Therefore, the release time lag can be reduced.

(3) In the photometric device of (1) or (2) above, the validity determining unit 533 determines that the minimum value of the photometric output data is greater than the lower limit level, or the maximum value of the photometric output data is greater than the effective determination level. Therefore, the photometry calculation is performed only in the case of the photometry output data for which reliability can be expected. As a result, it is possible to obtain appropriate photometry data by eliminating unnecessary calculations.
This also increases the possibility of reducing the release time lag.

(4) In the photometric devices of the above (1) to (3), the microcomputer 53 further sets the accumulation time and gain calculation unit 532 so that the upper limit of the accumulation time is changed longer than the upper limit in the normal mode in the low luminance shooting mode. Since the control is performed, the level of the photometric output data in the dark environment can be increased as compared with the case where the upper limit of the accumulation time in the normal mode is set.

(5) In the photometric device of the above (4), the microcomputer 53 changes the lower limit level to a smaller value in accordance with the upper limit of the accumulation time, so comparison is performed when determining whether the photometric output data is valid. Can be done appropriately.

(6) In the photometric device of the above (4) or (5), the microcomputer 53 changes the validity judgment level to a small value according to the upper limit of the accumulation time, and therefore judges whether or not the photometric output data is valid. The comparison can be made appropriately.

  The above description is merely an example. For example, an electronic camera or a film camera may be used as long as the camera includes the above-described photometric device, and the present invention may be applied to a camera different from the single-lens reflex type.

  The above description is merely an example, and is not limited to the configuration of the above embodiment.

DESCRIPTION OF SYMBOLS 2 ... Shooting optical system 4 ... Camera body 5 ... Main mirror 8 ... Penta prism 11, 12 ... Photometry optical system 13 ... Photometry sensor 51 ... A / D conversion part 52 ... Signal processing part 53 ... Microcomputer 54 ... Release button 55 ... Mode setting member 531 ... Photometric sensor control unit 532 ... Accumulation time, gain calculation unit 533 ... Effectiveness determination unit 534 ... Target level, effectiveness determination level calculation unit 535 ... Bv value calculation, exposure calculation unit 536 ... Photometry region setting unit

Claims (8)

A first metering mode for metering using an output signal from the light receiving element and a second metering mode for metering in an environment darker than the first metering mode using the output signal from the light receiving element can be set. A setting section;
When the setting unit is set to the first photometry mode or the second photometry mode, when the maximum value of the output signal is larger than the first value, the light is output from the light receiving element after the output signal. When the setting unit is set to the first metering mode and the maximum value of the output signal is smaller than the first value , the maximum value of the output signal is the first value. greater than the value smaller than the second value, it performs photometric calculation using the output signal when the minimum value of the output signal is less than the third value smaller than the second value, the setting section When the second photometry mode is set and the maximum value of the output signal is smaller than the first value , the maximum value of the output signal is larger than a fourth value smaller than the second value, and the output signal minimum value than said third value of Using the output signal when not smaller than again the fifth value metering device comprising a row intends calculating unit photometric calculation. The photometric device according to claim 1,
When the setting unit is set to the first photometry mode, the computing unit performs the photometric computation using the output signal when the maximum value of the output signal is smaller than the second value. When the accumulation time of the light receiving element is calculated using an output signal, and the setting unit is set to the second photometry mode, the output signal when the maximum value of the output signal is smaller than the fourth value A photometric device that calculates the accumulation time of the light receiving element using the output signal without performing photometric calculation using the. A photometric device according to claim 1 or claim 2, wherein
The photometric device wherein the third value is smaller than the fourth value. A photometric device according to any one of claims 1 to 3, wherein
The calculation unit determines that the output signal is not valid when the maximum value of the output signal is smaller than the second value when the setting unit is set to the first photometry mode, A photometric device that determines that the output signal is not valid when the maximum value of the output signal is smaller than the fourth value when the setting unit is set to the second photometric mode. In the photometry apparatus as described in any one of Claims 1-4,
A calculation unit that calculates the next accumulation time so that the photometric output from the light receiving element approaches a predetermined target value;
The computing unit changes the upper limit of the accumulation time longer when the setting unit is set to the second photometry mode than when the setting unit is set to the first photometry mode. Photometric device. The photometric device according to claim 5,
The photometric device according to which the difference between the third value and the fifth value corresponds to the upper limit length of the accumulation time. The photometric device according to claim 5 or 6,
The photometric device according to which the difference between the second value and the fourth value corresponds to the upper limit length of the accumulation time. A camera comprising the photometric device according to claim 1.

Images