JPH05158103A - Exposure controller for camera - Google Patents

Abstract

PURPOSE:To obtain a photograph which is excellent in graininess and appropriately exposed by providing a means for inputting film information on loaded film and setting over-exposure amt. in accordance with the film information in the case of over-exposing. CONSTITUTION:In the case of color negative film, a brightness difference DELTABv between maximum and minimum measured brightness values obtained by performing division photometry is found (#401), and in the case of DELTABv<5, the over-exposure Ov is increased by one step because margin being over is large (#402, #403). Next, when trimming magnification EZ is larger than 1-power, the exposure Ov is increased by one step to male an over amount large because the graininess is conspicuous (#404, #405). When the trimming magnification EZ is high (>=1.4-power), the exposure Ov is increased further by 0.5 steps (#406, #407). Then, photographing magnification beta is found from an object distance D and the focal distance (f) of a lens, and when beta is small (<1/80), the exposure Ov is increased further by one step to improve the graininess because the graininess is conspicuous.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a camera exposure control device.

[0002]

2. Description of the Related Art In an exposure device of a camera having a normal photographing mode and a trimming photographing mode, when the trimming photographing mode is selected, the exposure value exceeds an appropriate value required by subject brightness and film sensitivity. It has been proposed to control (overexpose) and improve the graininess of the film. At this time, if the overexposure amount in the exposure is within the range of the latitude of the negative film, a photograph of proper exposure can be obtained by exposure correction during printing on photographic paper in the laboratory.

[0003]

However, in the exposure control device, the overexposure amount is constant regardless of the type of the loaded film. Therefore,
When shooting with various films, the exposure value that maximizes the graininess of the film varies depending on the film,
In some films, problems such as deterioration of image quality due to overexposure or insufficient improvement of graininess occur.

[0004]

SUMMARY OF THE INVENTION The present invention has been made in view of the above circumstances, and includes photometric means for measuring subject brightness.
Film information input means for inputting film information including film sensitivity from the loaded film, deciding means for deciding an exposure value on the basis of subject brightness measured by the photometric means and sensitivity of the film, and deciding means by the deciding means. In a camera exposure control device including exposure control means for controlling the exposure based on the exposure value, the determining means is set to exceed an appropriate exposure amount determined based on the subject brightness and the film sensitivity. The exposure value is determined, and the overexposure amount is determined based on the film information input by the film information input means.

[0005]

The exposure control device for a camera constructed as described above provides an optimum overexposure for the loaded film when the exposure is controlled to be overexposed in order to improve the graininess of the film. It becomes possible to provide.

[0006]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An exposure control apparatus for a camera for performing overexposure control according to an embodiment of the present invention will be described below with reference to the drawings.

FIG. 1 is a functional block diagram of a camera equipped with an exposure control device to which the present invention is applied. The microcomputer 10 controls the operation of each block, which will be described later, and performs calculations such as exposure calculation.

The lens block 11 is a lens for photographing,
The focal length f, the maximum aperture value AvMAX, and the maximum aperture value Av0 are output to the microcomputer 10.

The AF block 12 measures the distance to the subject and outputs the value D to the microcomputer 10.

The flash block 13 emits light at the time of photographing under a low brightness to give a light amount necessary for photographing, and outputs a guide number GNo to the microcomputer 10.

The photometry block 14 evenly divides the screen into 25 areas (FIG. 11), performs photometry in each area, and outputs the measured brightness value Bvn (n = 1 to 25) to the microcomputer 10.
Output to.

The aperture control block 15 controls the aperture value of the taking lens according to a command from the microcomputer 10.

The SS control block 16 exposes the film with the shutter speed supplied from the microcomputer 10.

The winding block 17 winds the film.

The mechanical charge block 18 is a shutter.
Charge.

The display block 19 displays information for photographing.

The data reading block 20 reads the information magnetically written on the film (film sensitivity, negative / positive information, color / monochrome information, etc.) and sends it to the microcomputer. The data writing block 21 uses magnetic recording to record photographing information (trimming magnification information, overexposure amount information, etc.).
Write on the film.

The switch S11 is an exposure correction switch. Depending on the state of the switch, it is possible to set it from 0.5 step below to 1 step over at 0.5 step intervals.

The switch S12 is an exposure mode setting switch. P mode in which the camera automatically sets the aperture and shutter speed according to the brightness of the subject, and A mode in which the camera automatically sets the shutter speed when the aperture is manually set.
One of the four modes, S mode in which the camera automatically sets the aperture when the shutter speed and shutter speed are manually set, and M mode in which the aperture and shutter speed are manually set.
You can choose one.

The switches S13 and S14 are an aperture setting switch and a shutter speed setting switch. In each case, a signal is input to the microcomputer 10 each time it is turned on,
Each set value can be increased by one step.
However, if it is turned on when the set value is the highest value, the set value will return to the lowest value.

The switch S15 is a flash light emission switch. When the switch S15 is OFF, the flash light is not emitted, but when it is ON, it is emitted.

The switch S16 is an overexposure cancel switch. When the switch S16 is OFF, the overexposure is performed according to the algorithm of the overexposure control, but when it is ON, the overexposure is not performed.

Switches S17 and S18 are trimming magnification setting switches. The trimming magnification can be arbitrarily set between 1 and 2. Switch S17 to O
When N is set, the trimming ratio is increased, and switch S18 is set to O.
When N is set, the trimming ratio decreases.

The switch S1 is a photometric switch. It is turned on by pressing the release button (not shown) halfway,
When turned on, photometry and distance measurement are performed.

The switch S2 is a release switch.
The release button is pressed to turn it on, and when it is turned on, exposure is started.

Next, the operation of the camera constructed as described above will be described with reference to the flowcharts of FIGS.

In FIG. 2, when the operation of the microcomputer 10 is started, the state of the flash light emission switch S15 is checked (# 100). If ON, proceed to # 112. OFF
If so, check the exposure mode setting switch S12 (# 1
01, # 102, # 107) In P mode, # 112
I will proceed. In the M mode and the A mode, the state of the aperture setting switch S13 is checked (# 103), and if it is ON, the current set aperture value Av is increased by one step (# 104). However, when this value is larger than the maximum opening value AvMAX (# 10
In 5), the maximum aperture value Av0 is set (# 106).

In the M mode and the S mode, the state of the shutter speed setting switch S14 is checked (# 10
8) If it is ON, the current set time value Tv is increased by one step (# 109). However, when this value is larger than the maximum time value TvMAX (# 110), the minimum time value TvMIN is set (# 111).

Next, the photometric switch S1 is checked (# 11
2) If ON, the S1 processing routine described later is entered.
If it is OFF, the process returns to # 100.

Next, the S1 processing routine will be described with reference to FIG. First, the data reading block 20 inputs the sensitivity value Sv (film sensitivity) from the film (# 300). Next, the focal length f, the maximum aperture value Av0 and the maximum aperture value AvMAX are input from the lens block 11 (# 301), and the guide number GNo is input from the flash block 13 (# 302). Then, the metering block 14 performs divided metering to obtain the subject brightness value Bvn.
(N = 1 to 25) is calculated (# 303). Next, the AF block 12 measures the distance, obtains the distance D to the subject (# 304), and averages the photometric data Bvn (n = 1 to 25) to obtain the control brightness value BvT (# 305). Then, after entering an over amount determining routine described later (# 306), an over exposure amount Ov is determined, and then an exposure calculating routine described later is entered (# 307). Then, the shooting conditions are displayed (# 30
8). At this time, the overexposure cancel switch S16
When is ON or in M mode, the shutter speed and aperture value that can obtain proper exposure are displayed. Further, when the overexposure cancel switch S16 is OFF and the P, A, and S modes are set, the shutter speed at which overexposure is obtained,
Displays the aperture value and the overexposure amount. here,
Although the overexposure amount is displayed in addition to the shutter speed and the aperture value, it may only be displayed whether or not overexposure is performed. Next, the states of the photometric switch S1 and the release switch S2 are checked (# 309, # 31).
4). When both the photometric switch S1 and the release switch S2 are OFF, the process returns. Release switch S2
Is OFF and the photometric switch S1 is ON, the process returns to # 300. If the release switch S2 is ON in # 309, exposure is performed by performing aperture control (# 310) and shutter speed control (# 311) based on the aperture value and shutter speed obtained in the exposure calculation routine described above. After that, the film is rolled up and the mechanism is ready for the next shooting.
(# 312). Simultaneously with winding, the photographing conditions (overexposure amount, trimming magnification information, etc.) are written on the film by the data writing block 21 (#
313), and returns.

Next, the routine for determining the over amount is shown in FIG.
Will be explained. First, the overexposure amount Ov is reset (# 400). Then, the overexposure cancel switch S16 is checked (# 414), and if it is ON, the process returns with the overexposure amount Ov = 0. If it is OFF, the color / black and white of the film and the negative / positive are discriminated (#
415, # 416), if it is not a color negative film, the process returns. In the case of a color negative film, the maximum value B of the measured brightness values Bvn (n = 1 to 25) obtained by divided photometry
Find the difference ΔBv between vMAX and the minimum value BvMIN (# 40
1). When the brightness difference ΔBv is small (less than 5), it is over.
Since there is a large margin to perform, the overexposure amount Ov is increased by one step (# 402, # 403). Next, the trimming magnification EZ is 1
If it is more than twice, the graininess is conspicuous, and the overexposure amount Ov is increased by one step to increase the over amount (# 40).
4, # 405). When the trimming magnification EZ is high (1.4 times or more), the overexposure amount Ov is further increased by 0.5 step (# 406, # 407). Next, the photographing magnification β is obtained from the subject distance D and the focal length f of the lens (#
408), when the photographing magnification β is small (less than 1/80), the graininess is conspicuous. Therefore, the overexposure amount Ov is increased by one step to improve the graininess (# 409, # 410). Since the image quality may be rather deteriorated by excessive overexposure, the maximum over amount OvMAX is determined from the film information (film sensitivity) in the maximum over amount determination routine (# 411) described later. When the overexposure amount Ov is larger than this, the maximum overexposure amount OvMAX is set to the overexposure amount Ov (# 412, # 413). Here, the increase amount of the overexposure amount due to the trimming magnification or the like is not limited to the above value, and can be arbitrarily set according to the characteristics of the film. Also, the overexposure amount may be set for each country and region in accordance with the characteristics of the most distributed film. Further, the determination method for determining whether or not the overexposure amount is increased is not limited to the above-described determination method, and can be arbitrarily determined according to the specifications of the camera. For those having various shooting modes, the shooting mode may be added as a condition. On the contrary, the overexposure may be performed in all photographing.

Next, the maximum over amount determination routine will be described with reference to FIG. Generally, the higher the film sensitivity, the worse the graininess, so it is better to increase the overexposure amount. If the film sensitivity is low, it is not necessary to overexpose the image, and the image quality may be deteriorated.
It is better to control the amount of exposure. Therefore, the maximum over amount OvMAX is determined for each film sensitivity. Film sensitivity is 100
In the following, the maximum over amount OvMAX = 1 is set (# 500,
# 501), when the film sensitivity is 400 or less, the maximum over amount OvMAX = 2 (# 502, # 503), and when the film sensitivity is higher than 400, the maximum over amount OvMA.
X = 3 (# 504). In addition, the maximum over amount OvMAX
Is not limited to the above value and can be arbitrarily set according to the characteristics of the film. The maximum over amount may be set according to the characteristics of the most distributed film for each country or region. Further, in this embodiment, the overexposure amount is determined under various conditions within the range of the maximum overexposure amount, but the overexposure amount may always be equal to the maximum exposure amount during overexposure.

Next, the exposure calculation routine will be described with reference to FIG. When the flash light emission switch S15 is ON (# 600), since the image is taken with the aperture value according to the subject distance, the flash processing routine is entered (# 601). OF
In the case of F, the shutter speed and diaphragm are controlled according to the brightness of the subject. First, the exposure mode selected with the exposure mode setting switch S12 is checked (# 602), and the M mode is selected.
If not, the control brightness value BvT is overwritten in advance.
The exposure amount Ov is subtracted (# 603). In the M mode, the aperture and shutter speed are determined by the photographer with reference to the photometric value, so the overexposure amount is not included in the subject brightness BvT. Next, check the exposure compensation switch S11 (# 60
4) If correction is to be performed, the exposure correction routine described below is entered, and exposure correction is performed on a value that takes into account the overexposure amount (# 605). However, in the M mode, correction is performed for a value that does not include the overexposure amount. Then, check the exposure mode setting switch S12 (# 606, # 607),
If it is S or M mode, proceed to # 614, and Av, which will be described later,
Enter the Tv decision routine. If it is not in S or M mode (P
(A mode) The camera shake limit time value TvH is calculated from the focal length f of the lens (# 608), and the subject brightness limit BvH corresponding to the camera shake limit speed is calculated (# 609). Over
If the subject brightness value BvT for which the exposure amount has been corrected is larger than the shake limit brightness value BvH, the process proceeds to (# 610) and # 614. If it is smaller, the difference is checked (# 611). If it is larger than the overexposure amount Ov, it means that the brightness is too low before the overexposure amount is added, so the overexposure is performed as it is. Overexposure amount O for shooting without
Add v to BvT and return to the original (# 612). If the difference is less than the overexposure amount Ov, BvH is added to BvT to perform overexposure as long as the camera shake limit allows (# 61).
3). Then, an Av / Tv determination routine, which will be described later, is entered to obtain the aperture value and the shutter speed (# 614), and the process returns. Here, overexposure is performed within a range that does not cause camera shake, but a detection means for detecting that a tripod is attached is further provided, and when the tripod is attached, overexposure is performed regardless of the camera shake limit shutter speed. You may do it.

Next, the exposure correction processing routine will be described with reference to FIG. Check the exposure compensation switch S11 (#
700, # 702, # 704, # 706) If the exposure correction value is -0.5 Ev, 0.5 is added to the control brightness value BvT (# 701). If −1.0 Ev, the control brightness value Bv
Add 1.0 to T (# 703). If +0.5 Ev, 0.5 is subtracted from the control brightness value BvT (# 705). +
If 1.0 Ev, 1.0 is subtracted from the control brightness value BvT (# 707). In this embodiment, when performing the exposure correction, the exposure correction is performed for the exposure value for overexposure, but when performing the exposure correction, the exposure correction may be performed for the proper exposure value. ..

Next, the flash processing routine is shown in FIG.
Will be explained. First, the flash guide number
The illumination illuminance value Iv of the flash is obtained from the GNo and the film sensitivity Sv (# 800). Next, the distance value Dv is obtained from the subject distance D (# 801). And the irradiation illuminance value I
From v, the film sensitivity Sv, and the distance value Dv, the photographic aperture value AvC when the overexposure amount Ov is over is obtained (# 802). And shooting shutter speed TvC
Is the synchronized shutter speed TvX of the camera (# 8
03). The shooting aperture value AvC is the maximum aperture value AvMAX of the lens.
If it is larger than the above value, overexposure occurs, so the excess amount Δ is obtained, and the maximum aperture value AvMAX is added to the photographic aperture value AvC (#
804, # 805, # 806). When the photographic aperture value AvC is smaller than the open aperture value Av0 of the lens, the exposure is insufficient, so the shortage Δ is obtained, and the open aperture value Av0 is added to the photographic aperture value AvC (# 807, # 808, # 80.
9). Based on the amount of Δ, the amount of overexposure written on the film is corrected.

Next, the routine for determining Av and Tv is shown in FIG.
Will be explained. First, the control exposure value EvT is obtained from the control brightness value BvT and the film sensitivity Sv (# 900).
The exposure mode set by the exposure mode setting switch S12 is checked (# 901, # 904, # 907), and if it is A mode, the aperture value Av set to the photographing aperture value AvC is set.
Is entered (# 902), and the photographing shutter speed TvC is determined by the APEX method. In S mode, the shutter speed Tv set to the shooting shutter speed TvC
Is entered (# 905), and the photographing aperture value AvC is determined by the APEX method (# 906). In P mode, the shooting shutter speed TvC and the shooting aperture value AvC from the program diagram
(# 908). A description of the program diagram will be omitted. In the M mode, the shooting aperture value AvC, the aperture value Av set to the shooting shutter speed TvC, and the shutter speed Tv are entered (# 909, # 910).
Then, the shutter speed TvC and the aperture value AvC are checked (# 911). Here, it is checked whether the shutter speed TvC and the aperture value AvC obtained by the above method are within the control range of the shutter speed and the aperture value determined by the shutter, the lens, and the like. The shutter speed TvC and the aperture value AvC are replaced with control limit values. Then return.

Next, the printing apparatus in the laboratory is shown in FIG.
Will be explained.

Reference numeral 1 denotes a light source for printing, which is a light source for exposing an image on a film to photographic paper. 2 is a filter. When printing, the color temperature is corrected. Reference numeral 3 is a negative film feeding unit. Reference numeral 4 denotes a printing paper feeding unit. 5 is a data reading unit. The magnetically recorded information (overexposure amount information, trimming magnification information, etc.) on the film fed by the negative film feeding unit is read. 6 is a photometric unit. Meters the image on film when exposed to photographic paper. Reference numeral 7 is an optical system for photometry. The photometric area on the film is changed according to the trimming magnification information read from the film. Reference numeral 8 is an optical system for printing. The focal length is switched according to the trimming information read from the film. 9 is a photographic printing paper. Reference numeral 10 is a print density control unit. Data reading unit 5, photometric unit 6
Further, the overexposure amount information and the negative film photometric information are input, and when the overexposure is performed, the overexposure is exposed to the underexposure with respect to the standard exposure time. When the overexposure is not performed, the exposure time is adjusted based on the information from the photometry unit 6. Reference numeral 11 is a negative film. It is fed by the negative film feeding unit.

In the above embodiments, the example in which the film sensitivity, color / black and white, and negative / positive information are input as the film information to determine the overexposure amount is shown. However, by increasing the types of film information, It becomes possible to perform effective exposure control. For example, the latitude range or the best graininess overshoot of the film. When the latitude range or the best granularity over amount information is input, the maximum over amount in the above-described embodiment may be determined by the above value. Latitude information is also taken into consideration for the amount of graininess best recorded on the film,
It is preferred to record the best graininess overshoot within the latitude range. When both the latitude range and the graininess best over amount are input, either one may be set as the maximum over amount according to the film sensitivity, the trimming magnification, and the like. FIG. 12 is a flowchart showing a method of determining the over amount. First, the priority mode is determined (#
1200). The determination method will be described later. Next, the determined priority mode is discriminated (# 1201). In the granularity priority mode, # 1203, and in the normal mode, # 1
202, in the latitude priority mode, proceed to # 1204. In # 1202, it is determined which of the latitude upper limit and the graininess best over amount is larger. If the latitude upper limit is larger, the process proceeds to # 1204, and if the graininess best over amount is larger, the process proceeds to # 1203. In # 1203, the best granularity over amount is set to the maximum over amount OvMAX.
In 1204, the upper limit of latitude is set to the maximum amount OvMA.
Let it be X. Therefore, in the normal state, the smaller one of the latitude upper limit value and the graininess best over amount becomes the maximum over amount OvMAX. Next, the priority mode determination method is shown in FIG.
It is as shown in 3. The priority mode is determined by the film sensitivity and the trimming magnification. For example, when the film sensitivity is ISO400 and the trimming magnification is 1.5 times, the normal mode is selected.

In the above-described embodiment, when the maximum over amount is determined by the latitude information, it is not necessary to limit it to the upper limit of the latitude, and it may be determined by subtracting a predetermined amount from the upper limit of the latitude. ,or,
The predetermined amount may be determined by the brightness distribution in the shooting screen.

[0041]

As described above, in the exposure control device of the camera to which the present invention is applied, when the exposure is controlled so as to be over the proper exposure in order to improve the graininess of the film, the loading control is performed. By setting the optimum over amount according to the information input from the recorded film, for example, the film sensitivity, it is possible to obtain a photograph with excellent graininess and proper exposure on various films.

[Brief description of drawings]

FIG. 1 is a block diagram of a camera including an exposure control device to which the present invention is applied.

FIG. 2 is a flowchart showing the overall operation of the camera.

FIG. 3 is a flowchart showing an operation when a switch S1 is turned on.

FIG. 4 is a flowchart showing a method for determining an overexposure amount.

FIG. 5 is a flowchart showing a method for determining a maximum overexposure amount.

FIG. 6 is a flowchart of exposure calculation.

FIG. 7 is a flowchart of exposure correction processing.

FIG. 8 is a flowchart of exposure calculation during flash photography.

FIG. 9 is a flowchart for determining a shutter speed and an aperture value.

FIG. 10 is a block diagram of a printing apparatus in a lab.

FIG. 11 is a diagram showing a division state of a photometric area within a screen.

FIG. 12 is a flowchart showing a modification of the method of determining the maximum overexposure amount.

FIG. 13 is a diagram showing a method of determining a priority mode.

[Explanation of symbols]

 1 ... Light source for printing 2 ... Filter 5 ... Data reading unit 6 ... Photometric unit 10 ... Print density control unit

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Hiroyuki Okada 2-3-13 Azuchi-cho, Chuo-ku, Osaka, Osaka International Building Minolta Camera Co., Ltd. (72) Inventor Kazuo Kimura 2-chome, Azuchi-cho, Chuo-ku, Osaka No. 13 Osaka International Building Minolta Camera Co., Ltd.

Claims (3)

[Claims] 1. A photometric means for measuring subject brightness, a film information input means for inputting film information including film sensitivity from a loaded film, and a subject brightness and film sensitivity measured by the photometric means. An exposure control device for a camera, comprising: a determining unit that determines an exposure value; and an exposure controlling unit that controls exposure based on the exposure value determined by the determining unit, wherein the determining unit determines the subject brightness and the film sensitivity. The exposure value is determined to be over the appropriate exposure amount determined based on the above, and the overexposure amount is determined based on the film information input by the film information input means. Exposure control device for the camera. 2. The exposure control device for a camera according to claim 1, wherein the film information is film sensitivity information. 3. The exposure control device for a camera according to claim 1, wherein the film information is information regarding film graininess.