JP2006243186A - Camera - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a camera capable of easily taking a picture of high quality, and also, shortening a release time lag. <P>SOLUTION: An exposure control is performed by varying a F value and a shutter speed in accordance with an exposure target value calculated by a control part 19, and also, within a prescribed extent (2<EV value<8.5) as the calculated exposure target value, the exposure control is performed by fixing the F value and varying only the shutter speed. In an extent (EV value≥8.5) exceeding the prescribed extent, the exposure control is performed by varying both the F value and the shutter speed. In the case a film sensitivity is equal to or exceeding a prescribed sensitivity (ISO 1600), in a specified extent (14≤EV value≤15.5), the exposure control for the specified extent is performed by using an F value (for example, F value=11) which is set higher than the F value set for the lower limit of the specified range. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a camera that can perform high-quality shooting according to ambient brightness.

In recent years, as a camera that can easily take high-quality photos without strobe lighting, “Masahiro Kimura, utilizing color negative film” “Fuji Film“ Natural Photo System ”NATURA”, Photo Industry, Photo Industry Publishing Company, 2004 A natural photo system described in November 1, Vol. 62, No. 11, P43-45 (Patent Document 1) is known. When the film sensitivity is equal to or higher than a predetermined sensitivity, this natural photo system can perform photographing with natural light without emitting light with a strobe, and can obtain a high-quality photograph.
Masahiro Kimura, “Fuji Film“ Natural Photo System ”NATURA”, which utilizes color negative film, Photo Industry, Photo Industry Publishers, November 1, 2004, Vol. 62, No. 11, P43-45

  Here, in this natural photo system, the focus lens is moved in order to perform a focusing operation according to the distance to the subject. Therefore, there is a so-called release time lag from when the release button is pressed to when shooting is actually performed by opening and closing the shutter.

  SUMMARY OF THE INVENTION An object of the present invention is to provide a camera that can easily take high-quality photographs and reduce the release time lag.

  In order to solve the above-described problems, a camera according to the present invention includes a sensitivity detection unit that detects imaging sensitivity of an imaging medium, a luminance detection unit that detects external light luminance, and a sensitivity of the imaging medium determined by the sensitivity detection unit. If the external light luminance detected by the luminance detection means is in the predetermined first luminance region, the first reference value is determined from the exposure reference value corresponding to the detected external light luminance. The exposure target value is calculated by subtracting the exposure correction value of 1, and when the sensitivity detection unit detects that the sensitivity of the imaging medium is equal to or higher than a predetermined sensitivity, the external light luminance detected by the luminance detection unit Is set to a value smaller than the first exposure correction value from the exposure reference value corresponding to the detected outside light luminance. Second exposure compensation Exposure value calculating means for calculating an exposure target value by subtracting the value, and performing exposure control by making the F value and shutter speed variable according to the exposure target value calculated by the exposure value calculating means, and In a predetermined range of the exposure target value calculated by the exposure value calculation means, exposure control is performed so that only the shutter speed is increased as the exposure target value is increased while the F value is constant, and in a range exceeding the predetermined range. Performs exposure control so that the F value and the shutter speed increase as the exposure target value increases, and if the imaging sensitivity detected by the sensitivity detection means is greater than or equal to a predetermined sensitivity, it exceeds the predetermined range. In the specific range, the exposure control in the specific range is performed using an F value larger than the F value determined at the lower limit of the specific range. Includes an exposure control means for performing, the.

  According to the present invention, the exposure value calculation means calculates the exposure target value appropriately corrected according to the external light luminance, and the F value and the shutter speed according to the exposure target value calculated by the exposure value calculation means. In the predetermined range of the exposure target value calculated by the exposure value calculation means, and the exposure control is performed by changing only the shutter speed while keeping the F value constant. In a range exceeding the predetermined range, exposure control is performed by making both the F value and the shutter speed variable, and when the imaging sensitivity detected by the sensitivity detection means is equal to or higher than the predetermined sensitivity, the predetermined range is set. In the specified range, the exposure control in the specified range is performed using an F value that is larger than the F value determined at the lower limit of the specified range. That.

  Thereby, when the imaging sensitivity is equal to or higher than the predetermined sensitivity and the exposure target value is in the specific range, the exposure target value is in the specific range using an F value larger than the F value determined by the lower limit of the specific range. Exposure control can be performed, and pan focus can be expanded. That is, by expanding the pan focus, it is possible to perform an appropriate focusing operation on the subject without largely moving the focus lens. Therefore, time for moving the focus lens can be saved, the release time lag can be shortened, and light shooting can be performed.

  In addition, the camera of the present invention includes a distance measuring unit that measures the distance to the subject, and moves the focus lens according to the distance to the subject measured by the distance measuring unit at the time of shooting. Lens driving means for waiting the focus lens at a farthest set position suitable for photographing a subject.

  According to this invention, the distance to the subject is measured by the distance measuring means, and the farthest distance suitable for photographing the subject at the infinite distance by the lens driving means that moves the focus lens according to the measured distance. It is possible to wait at the set position. Thereby, when the distance to the subject is infinite (for example, 1050 mm or more), the lens driving unit does not need to move the focus lens for the focusing operation, and the time for moving the lens Can be saved, the release time lag can be shortened, and light shooting can be performed.

  Further, the camera of the present invention includes a distance measuring unit that measures a distance to a subject, a frequency measuring unit that measures a captured imaging frequency for each distance measured by the distance measuring unit, and the frequency measuring unit. Frequency storage means for storing the photographing frequency for each measured distance, and when photographing, the focus lens is moved according to the distance to the subject measured by the distance measuring means, and is stored in the frequency storage means. Lens driving means for causing the focus lens to stand by at a set position corresponding to a frequently occurring distance.

  According to the present invention, the distance to the subject is measured by the distance measuring means, the photographing frequency measured for each measured distance is stored in association with the focus lens at the set position corresponding to the stored high frequency distance. Can wait. As a result, the focus lens can be placed on standby at a frequently-set set position, and the possibility of moving the focus lens for focus control can be reduced, saving time for moving the focus lens and releasing the lens. The time lag can be shortened and light shooting can be performed.

  The present invention can provide a camera that can easily perform shooting with light that is close to reality, can reduce the release time lag, and can perform quick shooting.

  The present invention can be readily understood by considering the following detailed description with reference to the accompanying drawings shown for the embodiments. Subsequently, embodiments of the present invention will be described with reference to the accompanying drawings. Where possible, the same parts are denoted by the same reference numerals, and redundant description is omitted.

  First, exposure control which is a premise of the present embodiment will be described. FIG. 1 is a perspective view of the camera 10 of the present embodiment. As shown in FIG. 1, the lens shutter camera is loaded with a 135 film format cartridge. The camera 10 is provided with a release button 11 at its upper end. A lens barrel 20 incorporating a photographing lens 8 is attached to the center of the front surface of the camera 10. As this lens barrel, a photographic lens barrel that is capable of an auto-focusing operation including a lens 8 and a shutter is used. A finder 5, strobe light emitting unit 15, AF light projecting window 17 a and AF light receiving window 18 a are provided on the upper part of the camera 10. A light projecting unit (IRED (infrared light emitting diode)) 17 and a light receiving unit (PSD (position detecting element)) 18 which will be described later are arranged so that light can be emitted and received through the AF light projecting window 17a and the AF light receiving window 18a. The light projecting unit 17 and the light receiving unit 18 constitute a distance measuring unit that measures the distance to the subject based on the principle of triangulation, for example.

The camera 10 is provided with a photometric unit 13. The photometry unit 13 functions as a luminance detection unit that measures the external light luminance within the photographing field of view. As the photometric unit 13, for example, a center-weighted average photometric sensor provided with one SPD device (with an infrared cut filter built in the optical path) is used. This SPD device is approximately oriented on the optical axis of the taking lens optical system.
Next, the camera appearing in the perspective view will be described in detail. FIG. 2 is a block diagram of the camera 10 of the present embodiment. The camera 10 is applied to, for example, a lens shutter camera loaded with a 135 film format cartridge. The camera 10 includes a release button 11, a film sensitivity detection unit 12, a photometry unit 13, a memory unit 14, a strobe light emitting unit 15, a shutter unit 16, a light projecting unit 17, a light receiving unit 18, and a control unit 19. Hereinafter, each part will be described.

  The release button 11 is a button that is pressed when the user attempts to photograph a subject. When the release button 11 is pressed, the shutter unit 16 opens and closes the shutter.

  The film sensitivity detector 12 is a sensitivity detector that detects the sensitivity of a film loaded in a film loading unit (not shown). The film sensitivity detection unit 12 reads a portion representing sensitivity in the CAS code indicated by the film cartridge, and outputs the read information to the control unit 19. The control unit 19 can recognize the film sensitivity based on the output information. The film sensitivity is defined by ISO (International Organization for Standardization). The user may set the film sensitivity in manual operation.

  The photometry unit 13 is a luminance detection unit that detects external light luminance including luminance of a subject. Information indicating the luminance measured by the photometry unit 13 is output to the control unit 19, and the control unit 19 converts the external light luminance into a BV value (Brightness Value) in APEX units. An LV value (LightValue) (LV value = BV value + SV value) may be used.

  The memory unit 14 stores a correction control table, a program diagram, and an operation program. The correction control table is control information for storing the BV value and the ΔEV value in association with each other. The ΔEV value is an exposure correction value for correcting the exposure reference value. The exposure reference value is calculated, for example, by adding an SV value (Film Speed Value) in APEX units to the BV value. An EV value (Exposure Value) that is an exposure target value is calculated by subtracting the exposure correction value ΔEV from the BV value plus the SV value.

  A specific example of this correction control table is shown. FIG. 3 is a conceptual diagram of the correction control table. As shown in FIG. 3, the BV value and the ΔEV value are stored in association with each other. Based on the information stored in the correction control table, a ΔEV value corresponding to the BV value detected by the photometry unit 13 is set. Then, the corrected exposure target value EV is calculated by subtracting the ΔEV value from the exposure reference value calculated by the BV value + SV value.

The program diagram is control information in which EV values shown in APEX units for exposure control are associated with TV values (Shutter Speed Value) and AV values (Aperture Values) that are also APEX units. The TV value indicates the shutter speed, and the AV value is information indicating the F value (lens aperture) (see FIG. 8).

  The operation program is a program for performing a series of control processes related to the shooting operation in the camera 10.

  The strobe light emitting unit 15 emits strobe light to the subject automatically or by user operation based on the external light luminance measured by the photometry unit 13. Note that the strobe light emitting unit 15 in the present embodiment can be set so that it cannot be used within a predetermined range (for example, BV value <3).

  Based on the exposure control (shutter speed and F value (lens aperture)) by the control unit 19, the shutter unit 16 opens with a diameter indicated by the F value, and closes when the time indicated by the shutter speed has elapsed. The image obtained through the lens is transferred to the film while the shutter portion 16 is open. The shutter unit 16 includes a focus lens, and performs a focusing operation based on a distance to a subject measured by a distance measuring unit (to be described later) by a lens driving mechanism (not shown).

  The light projecting unit 17 is for measuring the distance to the subject and irradiates the subject with light.

  The light receiving unit 18 calculates the distance to the subject based on the light reflected from the subject by the light emitted by the light projecting unit 17. Specifically, the light receiving unit 18 outputs information indicating the light amount based on the received light to the control unit 19, and the control unit 19 calculates the distance to the subject based on the input information indicating the light amount. To do. The light projecting unit 17 and the light receiving unit 18 constitute a distance measuring unit.

  The control unit 19 is a control unit that controls the entire camera, and includes, for example, a CPU, a ROM, a RAM, an input signal circuit, an output signal circuit, and the like. This control part 19 performs the operation | movement flowchart mentioned later. For example, when the pressing of the release button 11 is detected, an instruction to operate the shutter unit 16 is output. Further, the film sensitivity is determined based on information from the film sensitivity detection unit 12. Further, the BV value is calculated based on the information indicating the light amount of the subject output from the photometry unit 13. When the state where the release button 11 is half-pressed is detected, the distance measuring unit is operated. Further, a corrected exposure target value is calculated by subtracting the exposure correction value (ΔEV) from the exposure reference value. Thus, the control unit 19 also functions as an exposure control unit that performs exposure control.

  Next, the operation | movement in exposure control of the camera 10 comprised in this way is demonstrated.

  First, an outline of exposure control in the camera 10 will be described. FIG. 4 is a conceptual diagram of exposure control, and schematically shows the correspondence between the BV value and the ΔEV value stored in the correction control table.

  As shown in FIG. 4, the vertical axis represents ΔEV value and the horizontal axis represents BV value. When the BV value is in the range of 0 to 3 (first luminance region), the ΔEV value is 2. Further, when the BV value is in the range of 3.5 to 9 (second luminance region), the ΔEV value is 1. Then, the exposure target value is calculated using the ΔEV value obtained here. That is, the exposure target value is calculated by subtracting the ΔEV value from the exposure reference value (Bv + Sv) obtained by adding the SV value to the BV value. Exposure control is performed using the EV value thus obtained. In FIG. 4, the ΔEV value in the first luminance area is 2 and the ΔEV value in the second luminance area is 1 and is expressed as a fixed value. However, the value is not limited to a fixed value. That is, in the graph of FIG. 4, the exposure correction characteristic may be inclined so as to increase or decrease the ΔEV value according to the BV value.

  Here, the first luminance region is a portion showing brightness assuming artificial lighting such as indoors. In recent years, since the atmosphere is emphasized, light sources having a low color temperature (about 3000K) such as tungsten and light bulb-colored fluorescent lamps are often used. Therefore, since the photometry of the camera is performed with a spectral sensitivity according to the standard relative luminous sensitivity, blue exposure tends to be insufficient under illumination with a low color temperature. Therefore, in the first luminance region, the two-level exposure is increased by the EV value so that the blue exposure can be increased. That is, the exposure target value is corrected to increase the exposure by subtracting the ΔEV value by 2 from the normal exposure reference value. Here, in order to surely perform shooting with natural light, it is possible to prevent the strobe light emitting unit 15 from emitting light. Specifically, when the BV value is in the first luminance region, a program that prohibits the light emission of the strobe light emitting unit 15 can be used. However, even in this case, it is possible to force the strobe to emit light by a user operation.

  The first luminance area is from the lower limit BV value of the shutter controllable range to a value where the BV value is 3. The lower limit of the shutter controllable range is the speed when there is a restriction on the shutter speed such as camera shake restriction. If there is no restriction, the BV value is in the range from -3 to 3.

  Further, the second luminance area is a portion showing the brightness assuming the time of cloudy or sunny weather outdoors. The color temperature in the second luminance area is moderate (about 5000K (Kelvin)), and when the BV value acquired by the camera is within the range of the second luminance area, giving appropriate exposure in most shooting environments. Appropriate shooting can be performed. Therefore, for the second luminance area, it is necessary to take into account variations in the amount of light in the shooting state. Then, in order to prevent the overall exposure from becoming insufficient, the EV value is increased by one step. That is, the exposure target value is corrected to increase the exposure by subtracting 1 from the exposure reference value calculated by the BV value + SV value.

  Note that the second luminance region is from a value where the BV value is 3.5 to the upper limit BV value of the shutter controllable range. The upper limit of the shutter controllable range is a speed when the shutter speed is increased to the limit or a range that can be controlled as a program.

  If the average correction value of the ΔEV value in the first luminance region is ΔE1 and the average correction value of the ΔEV value in the second luminance region is ΔE2, if the ΔEV value satisfying ΔE1−ΔE2 ≧ 0.8 can be obtained, An exposure correction value other than the ΔEV value shown in FIG. 4 may be set. Hereinafter, the reason why it is preferable to satisfy ΔE1−ΔE2 ≧ 0.8 will be described.

The spectral sensitivities for each wavelength in the red-sensitive layer, green-sensitive layer, and blue-sensitive layer in the color negative are Sr, Sg, and Sb. Further, when the relative intensities for each wavelength at the relative energy of 5000 K (Kelvin) and 3000 K (Kelvin) of the light source are I5000 and I3000, the result shown in the following formula (1) is obtained.

  Generally, the spectral sensitivity for each color in the color negative is as shown in the graph of FIG. Further, the relative intensity at the color temperature of a typical light source (indoor light source, outdoor light source) is as shown in the graph of FIG. Equation 1 below is a ratio calculated by multiplying the relative spectral sensitivity and the relative intensity at each wavelength of the green-sensitive layer and the blue-sensitive layer shown in FIGS. 5 and 6 and cumulatively adding them. .

From this formula (1), in the light source having a relative energy of 3000K, the blue-sensitive layer can only sensitize 1 / 2.15 light to the green-sensitive layer as compared with the light source having a relative energy of 5000K. Recognize. Based on the value calculated here, the exposure difference is converted using the following equation (2).

  This calculation result means that in the color negative, the blue-sensitive layer is exposed less by 1.11 in terms of the EV value than the green-sensitive layer.

  The photometry of the camera is performed with the standard relative luminous sensitivity according to the spectral sensitivity of the green sensitive layer. For this reason, if exposure correction of +1.11 in EV value is performed on the camera photometric value, appropriate exposure can be given also to the blue-sensitive layer. On the other hand, exposure correction of +1.11 in EV value is also applied to the green sensitive layer. However, since the color negative has a large latitude for overexposure, there is no problem even if it is overexposed.

  Then, it is preferable to perform exposure correction with a difference of 0.8 or more as an EV value (that is, ΔE1−ΔE2 ≧ 0.8) as a numerical value in consideration of actual light source variation and the like. When the ΔEV value is set to a substantially constant value in the first luminance region and the second luminance region (including a case where the ΔEV value is slightly increased or decreased), ΔE1 and ΔE2 are defined as average values in the respective ranges. Further, when the control is not such that the ΔEV value becomes a constant value (when the ΔEV value varies by 0.5 or more in each luminance region), the minimum value in the first luminance region is adopted as ΔE1, and ΔE2 is adopted. Adopts the maximum value in the second luminance region.

  The numerical condition of ΔE1−ΔE2 ≧ 0.8 is a numerical condition calculated in comparison with the 3000K and 5000K light sources, but there are various light sources in the real world. For example, when the above formula (2) is calculated in a comparison with a light source having a high color temperature, the EV value may be 0.5 to 0.8. In such a case, it is also preferable to set ΔE1−ΔE2 ≧ 0.5 as a numerical value assuming all light sources that actually exist.

  Next, a specific operation of the camera 10 based on the above-described concept of exposure control will be described. FIG. 7 is a flowchart showing the operation of the camera 10. The control process of this flowchart is executed by the control unit 19 based on a program stored in the memory unit 14.

  When the control unit 19 determines that the release button 11 of the camera 10 has been pressed (S1), the control unit 19 outputs an instruction to the photometry unit 13 to perform photometry processing. The photometry unit 13 detects the external light luminance and outputs a detection signal. The control unit 19 calculates a BV value that is a luminance value based on the input detection signal (S2).

  The control unit 19 calculates the exposure reference value by adding the SV value and the BV value corresponding to the film sensitivity (S3). For example, the EV value is calculated using a mathematical formula of EV value = BV value + SV value. Specifically, the APEX unit of the ISO 1600 film is +9, and when the BV value is 3, the exposure reference value is 9 + 3 = 12.

  Then, the control unit 19 determines whether or not the film sensitivity detected by the film sensitivity detection unit 12 is equal to or higher than the sensitivity indicated by ISO 1600 (S4).

  When the control unit 19 determines that the film sensitivity is equal to or higher than the sensitivity indicated by ISO 1600, the control unit 19 corrects the exposure reference value (S5). Specifically, the control unit 19 extracts a ΔEV value corresponding to the BV value calculated above from the correction control table. Then, the control unit 19 calculates the exposure target value by correcting the exposure reference value by subtracting the ΔEV value from the exposure reference value calculated in S3.

  The control unit 19 performs exposure control using the exposure target value EV (S6). Here, the exposure control is to control the aperture (AV value) and shutter speed (TV value) of the lens. This exposure control is performed using, for example, a program diagram as shown in FIG.

  The control unit 19 instructs the shutter unit 16 to shoot using the determined shutter speed and F value, and the shutter unit 16 performs shooting (the aperture diameter of the shutter portion (blade) in the shutter unit 16 is set). The aperture is opened by the size indicated by the F value and is closed after a predetermined time indicated by the shutter speed) (S7).

  In S4, if the film sensitivity is less than ISO 1600, exposure control is performed with the normal value EV value = BV value + SV value (S8), and then photographing is performed (S7).

  In this way, exposure control based on film sensitivity can be performed, and high-quality imaging can be performed without using strobe light emission.

  Next, exposure control different from the exposure control shown in FIG. 4 will be described. FIG. 9 is a conceptual diagram of exposure control different from the exposure control shown in FIG.

  According to FIG. 9, for the first luminance region where the BV value is 0 to 5, the EV value is controlled to be increased by two stages. In addition, the EV value is not corrected for the second luminance region in which the BV value is 5.5 to 8. Furthermore, in another embodiment, when the BV value is less than 5, the strobe light is not emitted, and when the BV value is 5 or more, the strobe light is always emitted. Thereby, at least when indoors, it is possible to take a photograph with high quality and atmosphere without using strobe light emission. In addition, even when using the strobe light emission, the subject does not often stand out due to the strobe light emission, and a high-quality photograph can be taken.

  As described above, according to the camera 10 according to the embodiment relating to the exposure control, when the film sensitivity is high sensitivity of ISO 1600 or higher, the exposure correction value ΔEV1 of the first luminance area is set to the exposure of the second luminance area. By setting a large value of at least 0.5 Ev or more on average with respect to the correction value ΔEV2, appropriate exposure control according to the shooting environment can be performed, and shooting with light closer to reality can be easily performed without flash emission. Can do. In particular, in a shooting environment under indoor artificial lighting, appropriate exposure can be given to the blue-sensitive layer, and higher quality photography can be performed.

  At that time, if the exposure correction value ΔEV1 of the first luminance area is set to a large value of at least 0.8 Ev on average with respect to the exposure correction value ΔEV2 of the second luminance area, more appropriate exposure control according to the shooting environment can be performed, It is possible to easily perform shooting with light that is closer to reality without flashing. Also in this case, in a shooting environment under indoor artificial lighting, appropriate exposure can be given to the blue-sensitive layer, and higher quality photography can be performed.

  Further, the camera according to the embodiment relating to the exposure control preferably includes a strobe light emitting unit that emits strobe light, and when the external light luminance is a predetermined value or less, it is preferable not to emit light by the strobe light emitting unit. . Thereby, it is possible to prevent photographing with artificial light by strobe light emission and easily perform photographing with light that is closer to reality.

  Although this embodiment has been described based on a camera using a film, the camera according to the present invention is not limited to a camera using a film. For example, the present invention may be applied to a digital camera using a CCD. In this case, if the set sensitivity of the CCD is detected instead of detecting the film sensitivity and the set sensitivity is equal to or higher than the sensitivity corresponding to the ISO sensitivity 1600, the first brightness set to a lower brightness than the second brightness area. In the region, the exposure correction value is set to a large value of at least 0.5 Ev on average, and the exposure correction value is subtracted from the exposure reference value calculated based on the set sensitivity and the luminance value (Bv) to obtain an exposure target value. What is necessary is just to perform exposure control. Even in this case, the same operational effects as those of the camera according to the embodiment related to exposure control described above can be obtained.

  Next, a camera according to an embodiment in which the release time lag is reduced on the premise that the above-described exposure control is performed will be described. When performing exposure control according to the exposure target value, the camera shown in this embodiment performs exposure control using a special program diagram if the film has a predetermined sensitivity or higher (ISO 1600 or higher), and the film sensitivity is a predetermined sensitivity. If it is less than 1, exposure control is performed using a standard program diagram. This special program diagram sets an F value that is set to be larger than the F value defined in the normal program diagram in a specific range of the exposure target value. Details will be described below.

  The block diagram of the camera 10 of the present embodiment is the same as the block configuration diagram shown in FIG. 2, and the following functions are added to the functions of the control unit 19. That is, the control unit 19 performs exposure control by changing the F value and the shutter speed in accordance with the calculated exposure target value in addition to the above-described function, and also performs a predetermined range in the calculated exposure target value. In (for example, 2 <EV value <8.5), exposure control is performed by making only the shutter speed variable while keeping the F value constant. In a range exceeding the predetermined range (for example, EV ≧ 8.5), exposure control is performed by changing both the F value and the shutter speed. When the film sensitivity detected by the film sensitivity detection unit 12 is a predetermined sensitivity (for example, 1600) or more, in a specific range (for example, 14 ≦ EV value ≦ 15.5) in a range exceeding the predetermined range. Then, exposure control in the specific range is performed using an F value (for example, F value = 11) set larger than the F value set at the lower limit of the specific range. As described above, the control unit 19 functions as an exposure value calculation unit that calculates the exposure target value and an exposure control unit.

  Here, a specific example in the above-described exposure control is shown in FIG. FIG. 10 shows a special program diagram in this embodiment. When the exposure target value (EV value) is in a specific range (for example, 14 ≦ EV value ≦ 15.5), the program diagram is defined at the lower limit of the specific range, as compared with the standard program diagram. An F value larger than the F value is determined. In FIG. 10, F value = 11 is set in the range of “14 ≦ EV value ≦ 15.5”. Note that the F value here does not have to be fixed, and it is sufficient that an F value larger than the F value determined at the lower limit of the specific range is determined. Moreover, it is preferable to set to F value defined by the upper limit of the specific range as this embodiment.

Next, as shown in FIG. 10, the effect of setting the F value in the specific range to a value larger than the F value determined by the lower limit of the specific range will be described. FIG. 11 and FIG. 12 are AF diagrams showing the relationship between the allowable deviation width of the focus lens in the relationship between the size of the circle of confusion and the subject distance. In this AF diagram, the vertical axis indicates the size of the circle of confusion, and the horizontal axis indicates the distance to the subject. In FIG. 11, for example, when the focus lens is controlled to focus on a subject that is 723 mm away, the size of the circle of confusion that is acceptable for a subject that is 765 mm to 685 mm away (that is, Is within the depth of field). In this embodiment, FIG. 11 is an AF diagram when the focal length = 24 mm and the F value (FNO) = 2, and FIG. 12 is when the focal length = 24 mm and the F value (FNO) = 11. FIG.
Here, the circle of confusion will be described. When focusing a lens using a distance measuring device, the lens usually does not move linearly, but moves stepwise within an allowable range of focus deviation. When a “point” is photographed with such a camera, the “point” is formed on the film surface as long as the lens is in focus. In addition, the photographed “points” are formed in a blurred state on the film with a slight deviation within the allowable range. Such a blurred state is called a circle of confusion.

  As for the characteristics of an AF diagram in a general camera, when the numerical value indicated by the F value is increased, that is, when the aperture is reduced, the slope of the oblique line indicated by the AF diagram becomes gentler. That is, as the F value is increased, the focusing range by the focus lens becomes wider, and the necessity of moving the focus lens is increased.

  For example, in FIG. 11, since the F value is set to a small value of F value = 2 and the diaphragm is opened, the slope of the oblique line shown in the AF diagram is relatively steep. . Therefore, the tolerance of the deviation between the focus lens position and the subject distance with respect to the circle of confusion due to the focus lens is narrowed, and the focus lens is inevitably in an appropriate focus position so that focusing can be performed according to the distance to the subject. There are many cases to move to. Therefore, a time for moving the focus lens is required.

  On the other hand, in FIG. 12, since the F value = 11 and the F value is set to a large value and the aperture is narrowed, the slope of the oblique line shown in the AF diagram is relatively gentle. . Therefore, the tolerance of the deviation between the focus lens position and the subject distance with respect to the circle of confusion caused by the focus lens is widened, and the focus lens is inevitably in an appropriate focus position so that it can be focused according to the distance to the subject. The time for moving the focus lens is reduced, and the time for moving the focus lens is omitted. In FIG. 12, when the focus lens is set to always stand by at the farthest set position (the set position when the object distance is 2503 mm in FIG. 12), the object distance is 1050 mm or more. On the other hand, when shooting, the subject is in the tolerance range of the focus lens, so there is no need to move the focus lens, and the time for focusing operation by the focus lens can be omitted. .

  Next, a specific operation of the camera 10 in consideration of such characteristics will be described. FIG. 13 is a flowchart showing the operation of the camera 10. The control process of this flowchart is executed by the control unit 19 based on a program stored in the memory unit 14.

  When the control unit 19 determines that the release button 11 of the camera 10 has been pressed (S11), the control unit 19 outputs an instruction to the photometry unit 13 to perform photometry processing. The photometry unit 13 detects the external light luminance and outputs a detection signal. The control unit 19 calculates a BV value that is a luminance value based on the input detection signal (S12).

  The controller 19 calculates the exposure reference value by adding the SV value and the BV value corresponding to the film sensitivity (S13). For example, the EV value is calculated using a mathematical formula of EV value = BV value + SV value. Specifically, the APEX unit of the ISO 1600 film is +9, and when the BV value is 3, the exposure reference value is 9 + 3 = 12.

  Then, the control unit 19 determines whether the film sensitivity detected by the film sensitivity detection unit 12 is equal to or higher than the sensitivity indicated by ISO 1600 (S14).

  When determining that the film sensitivity is equal to or higher than the sensitivity indicated by ISO 1600, the control unit 19 corrects the exposure reference value (S15). Specifically, the control unit 19 extracts a ΔEV value corresponding to the BV value calculated above from the correction control table. Then, the control unit 19 calculates the exposure target value by correcting the exposure reference value by subtracting the ΔEV value from the exposure reference value calculated in S3. That is, when the detected external light luminance is in the predetermined first luminance area described in the above-described embodiment, the exposure target value is calculated by subtracting the first exposure correction value from the exposure reference value, and is detected. When the outside light luminance is in the second luminance region set to a region larger than the first luminance region, the exposure target value is calculated by subtracting the second exposure correction value from the exposure reference value. Note that the second exposure correction value is set to a value smaller than the first exposure correction value.

  The control unit 19 determines whether or not the exposure target value calculated in S15 is included in the specific range (14 ≦ EV value ≦ 15.5) (S16). In S16, when the exposure target value is not within the specific range, the control unit 19 performs exposure control using an F value defined by a special program diagram (the same F value as the F value defined in the standard program diagram). (S17). And the control part 19 image | photographs by the shutter part 16 (S20).

  In S16, when the exposure target value is included in the specific range, the control unit 19 uses a special program diagram based on the F value set larger than the F value determined at the lower limit of the specific range. Then, exposure control is performed (S18). Here, for example, when the exposure target value is in the range of “14 ≦ EV value ≦ 15.5”, exposure control using F value = 11 is performed. And the control part 19 image | photographs by the shutter part 16 (S20).

  In S14, when the control unit 19 determines that the film sensitivity is not equal to or higher than the sensitivity indicated by ISO 1600, the control unit 19 performs exposure control based on the F value defined by the standard program diagram (S19). And the control part 19 image | photographs by the shutter part 16 (S20).

  Thus, using a special program diagram, when the film sensitivity is ISO 1600 or higher and the exposure target value is in a specific range (14 ≦ EV ≦ 15.5), F defined by the lower limit of the specific range Using the F value (F value = 11) determined to be larger than the value, exposure control can be performed when the exposure target value is within a specific range, and pan focus can be expanded. That is, by expanding the pan focus, it is possible to perform an appropriate focusing operation on the subject without largely moving the focus lens. Therefore, time for moving the focus lens can be saved, the release time lag can be shortened, and light shooting can be performed.

  In such a camera, in order to shorten or omit the time for moving the focus lens, it is preferable to place the focus lens in a position where the photographing frequency is high in advance. The details will be described below with reference to FIG. FIG. 14 is a flowchart showing an operation when the focus lens is moved to the farthest set position.

  When photographing by the operation shown in FIG. 13 is completed (S21), immediately or after a predetermined time has elapsed, the control unit 19 determines whether or not to move the position of the focus lens (S22). That is, it is determined whether or not the focus lens was located at the farthest set position when the image was taken in S21.

  If the control unit 19 determines that the focus lens is not moved to the farthest set position and the focus lens is moved, the control unit 19 controls the lens driving mechanism (not shown) to set the focus lens farthest. It moves to the position, waits at the farthest set position, and prepares for the next photographing (S23). In S22, when the control unit 19 determines that it is not necessary to move, the process ends without performing movement control on the focus lens.

  In this way, by setting the focus lens setting position (standby position) to the farthest setting position, when the distance to the subject is infinite (for example, when it is 1050 mm or more (see FIG. 12)), lens driving is performed. With the mechanism, the focus lens for focusing operation is not moved, time for moving the focus lens can be saved, the release time lag can be shortened, and light shooting can be performed. That is, since the farthest set position when the F value is increased is considered to occupy most of the subject distance at the time of shooting, the release time lag at the time of shooting can be shortened and light shooting can be performed. Can do.

  Next, an operation for counting the shooting frequency (setting frequency for setting the focus lens) for each shooting object distance and waiting the focus lens at an appropriate in-focus position based on the counted shooting frequency will be described. FIG. 15 is a flowchart showing an operation when the focus lens is moved to an appropriate standby position according to the photographing frequency.

  When the shooting shown in FIG. 13 is completed (S31), the control unit 19 counts the set frequency (shooting frequency) at which the focus lens is set separately for each set position (S32), and the counted set frequency. Is stored in a memory (not shown) (S33). Note that it is assumed that the control unit 19 has moved the focus lens to the set position for focusing according to the distance to the measured subject at the time of shooting.

  Immediately after the end of storage or after a predetermined time has elapsed, the control unit 19 determines whether or not it is necessary to move the focus lens (S34). Here, in order to move the focus lens to the most frequently set position based on the set frequency stored for each set position, the control unit 19 has the highest frequency and the most frequently set focus lens at the end of shooting. It is determined whether or not the setting position of the focus lens matches.

  If the control unit 19 determines that the focus lens needs to be moved, the control unit 19 moves the focus lens to the most frequently set position using the lens driving mechanism (S35). If it is not necessary to move the focus lens, the process ends without giving an instruction to the lens driving mechanism.

  Thus, by determining the standby position of the focus lens based on the set frequency (shooting frequency) for each set position at the time of shooting, the possibility of driving the focus lens for focus control can be reduced. The time for moving the focus lens can be saved, the release time lag can be shortened, and light shooting can be performed. Further, when the determination of moving the focus lens (determination shown in S34) is performed after the end of shooting (after storing the set position) and after a predetermined time has elapsed, the focus lens is not driven at the time of shooting. You can shoot continuously.

It is a perspective view of the camera 10 of this embodiment. It is a block block diagram of the camera 10 of this embodiment. FIG. 3 is a conceptual diagram of a correction control table in the camera of FIG. 2. It is a conceptual diagram of exposure control in the camera of FIG. It is a figure which shows the spectral sensitivity of a color negative. It is a figure which shows the relative intensity of a typical light source. It is a flowchart which shows operation | movement of the camera of FIG. It is a program diagram which shows the specific example of exposure control in the camera of FIG. It is a conceptual diagram of exposure control different from the embodiment of FIG. The special program diagram in this embodiment is shown. FIG. 10 is an AF diagram when the F value = 2, showing the relationship between the allowable deviation width of the focus lens in the relationship between the size of the circle of confusion and the subject distance. FIG. 10 is an AF diagram when the F value = 11, showing the relationship between the focus lens displacement tolerance in the relationship between the size of the circle of confusion and the subject distance. It is a flowchart which shows operation | movement of the camera 10 of this embodiment. It is a flowchart which shows operation | movement when moving a focus lens to the farthest set position. It is a flowchart which shows operation | movement when moving a focus lens to the suitable standby position according to imaging | photography frequency.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 ... Camera, 11 ... Release button, 12 ... Film sensitivity detection part, 13 ... Photometry part, 14 ... Memory part, 15 ... Strobe light emission part, 16 ... Shutter part, 17 ... Light projection part, 18 ... Light reception part, 19 ... Control unit, 20 ... copper mirror.

Claims (3)

Sensitivity detection means for detecting the imaging sensitivity of the imaging medium;
Luminance detection means for detecting the ambient light luminance;
Detected when the sensitivity detection means detects that the sensitivity of the imaging medium is equal to or higher than a predetermined sensitivity, and the outside light brightness detected by the brightness detection means is in a predetermined first brightness area. The exposure target value is calculated by subtracting the first exposure correction value from the exposure reference value corresponding to the external light brightness, and the sensitivity detection unit detects that the sensitivity of the imaging medium is equal to or higher than a predetermined sensitivity. When the external light luminance detected by the luminance detection means is in the second luminance region set to a region larger than the first luminance region, the exposure reference value corresponding to the detected external light luminance is Exposure value calculating means for calculating an exposure target value by subtracting the second exposure correction value set to a value smaller than the first exposure correction value;
Exposure control is performed by varying the F value and the shutter speed according to the exposure target value calculated by the exposure value calculation means, and in a predetermined range in the exposure target value calculated by the exposure value calculation means. The exposure control is performed so that only the shutter speed increases with the increase of the exposure target value while keeping the F value constant, and in the range exceeding the predetermined range, the F value and the shutter speed increase with the increase of the exposure target value. If the imaging sensitivity detected by the sensitivity detection means is equal to or higher than a predetermined sensitivity, the specific range in the range exceeding the predetermined range is determined by the lower limit of the specific range. Exposure control means for performing exposure control in the specific range using an F value larger than the determined F value;
With a camera. Ranging means for measuring the distance to the subject;
When shooting, the focus lens is moved according to the distance to the subject measured by the distance measuring means, and the focus lens is put on standby at the farthest set position suitable for shooting a subject at infinity. Lens driving means;
The camera according to claim 1, further comprising: Ranging means for measuring the distance to the subject;
For each distance measured by the distance measuring means, a frequency measuring means for measuring the photographing frequency of photographing,
Frequency storage means for storing the photographing frequency for each distance measured by the frequency measurement means;
When taking a picture, the focus lens is moved according to the distance to the subject measured by the distance measuring means, and the focus lens is waited at a set position corresponding to the frequently stored distance stored in the frequency storage means. Lens driving means for causing
The camera according to claim 1, further comprising:

Images