JPH0611754A - Metering system for camera - Google Patents

Abstract

PURPOSE:To obtain the metering system of a camera which automatically executes photometry corresponding to respective trimming ranges and decides the optimum brightness value of an object in the case of the photometry of a trimming mode CONSTITUTION:This system is provided with a photographing mode switching means 1 which properly switches a mode to a normal photographing mode and the trimming photographing mode designating the printing of an area which is narrower than the area printed in the normal photographing mode, a divisional photometry means 2 which divides the printing range by the normal photographing mode to plural blocks and executes the photometry thereof, a weighting change means 3 changing weighting among the plural blocks corresponding to the switching means 1 and an arithmetic means 4 calculating the brightness of the object based on the output of the change means 3 by using an output from the photometry means 2.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a photometric system for a camera, and more particularly to a photometric system for a camera capable of obtaining an optimum exposure value in a trimming mode of a camera capable of trimming.

[0002]

2. Description of the Related Art Various photometric systems for cameras capable of trimming have been proposed so far. For example, a mode selection means for selectively switching between a normal shooting mode and a trimming mode in which a narrower range is printed, such as a camera capable of trimming shooting disclosed in Japanese Patent Laid-Open No. 62-112139. , Has a brightness measuring means for measuring the brightness of the subject and a light measuring range switching means for making the light measuring range of the brightness measuring means narrower than the light measuring range in the normal photographing mode when the trimming mode is selected, and switched to the trimming mode. Sometimes, it determines the exposure by measuring the subject brightness with a narrow metering range set by the zoom lens of the photometric optical system. Further, as in the trimming photographing camera disclosed in Japanese Patent Laid-Open No. 62-163031, a normal photographing mode and a trimming photographing mode capable of designating a range narrower than an area to be printed in the normal photographing mode are selected. The trimming photography mode is selected by the photographing mode selection means, the average photometry means for uniformly measuring the wide area of the subject, the partial photometry means for measuring the area narrower than the photometry area by the average photometry means. In some cases, it has a photometry mode selection means for selecting the partial photometry means and automatically determines the exposure by spot photometry within the trimming range when switching to the trimming photographing mode.

[0003]

However, in photometry in the trimming mode as in the camera disclosed in Japanese Patent Laid-Open No. 62-112139, when the angle of view is reduced by the zoom lens and the photometric range is narrowed, There is a drawback in that the precision of photometry becomes poor because the micro optical system is driven. Further, even if the spot metering is performed within the trimming range as in the camera disclosed in Japanese Patent Laid-Open No. 62-163031, the relationship between the trimming range and the spot metering range is not clear, so accurate metering can be performed. There is a problem that you can not do it. That is, since a light beam with a narrow angle of view is measured, there are cases where the angle of view for trimming and the photometric area do not match. If the angle of view is too narrow with respect to the angle of view for trimming, the photometric accuracy is likely to be significantly reduced. Further, it is desirable to subdivide the photometric sensor so as to correspond to each angle of view for trimming, but the sensor control becomes complicated and the sensor cost becomes higher.

An object of the present invention is to provide a photometric system for a camera, which can automatically determine photometry corresponding to each trimming range and determine an optimum exposure value when photometrically measuring a subject brightness in a trimming mode. It is in.

[0005]

As shown in the conceptual diagram of FIG. 1, a camera photometry system according to the present invention specifies a normal photographing mode and an area narrower than the area printed in the normal photographing mode. Shooting mode switching means 1 for appropriately switching the trimming shooting mode, divided photometry means 2 for dividing the print range in the normal shooting mode into a plurality of blocks for photometry, and between the plurality of blocks corresponding to the shooting mode switching means. It is characterized by further comprising a weight changing means 3 for changing the weight of the object, and a calculating means 4 for calculating the subject brightness based on the output of the weight changing means using the output from the divided photometric means.

[0006]

The shooting mode switched by the shooting mode switching means 1 is input to the weighting changing means 3. In addition, the divided photometry unit 2 divides the print range in the normal photographing mode into a plurality of blocks and inputs the photometric subject brightness into the calculation unit 4. Then, the weighting changing means 3 inputs the weighting coefficient between the plurality of blocks changed according to the photographing mode from the photographing mode switching means 1 to the calculating means 4. In the calculation means 4, the subject brightness measured for each block from the divided photometry means 2 and the weighting for each block from the weighting change means 3 in the designated shooting mode are used to select the shooting mode. The subject brightness in the entire print range is calculated.

[0007]

The present invention will be described below with reference to the illustrated embodiments. FIG. 2 is a block configuration diagram of a camera photometric system showing an embodiment of the present invention. The photometric system of this embodiment includes a three-divided AE sensor 12 and an I / F circuit 11 that converts a detected current into a voltage corresponding to a unit area of the AE sensor.
A detection voltage as a digital signal, weighting the voltage with a coefficient according to the trimming mode to determine the exposure value, and writing information about the trimming mode to the film, and a trimming setting circuit 14 for setting the trimming mode. Composed of and.

In this embodiment, the split photometric means 2 is used.
A three-divided AE sensor 12 is used as. This 3
The entire range of the divided AE sensor 12 corresponds to the print range in the normal shooting mode. The measurement range of the three-divided AE sensor 12 is a spot photometric range S at the center of the AE sensor 12 and the center of a concentric circle, and a range concentric with the spot photometric range S and wider than the range of the photometric range S, and It is divided into three ranges, a partial photometry range B not including the range S and a peripheral photometry range A other than the range S and the range B. Each range S, B, A of this three-division AE sensor 12
The detected current from is input to the I / F circuit 11. In the I / F circuit 11, the input detection current of each range S, B, A of the three-division AE sensor 12 is converted into a detection voltage corresponding to a unit area of the three-division AE sensor 12, This detected voltage is input to the CPU 13.

In the trimming setting circuit 14, the trimming mode is set and input to the CPU 13. In the CPU 13, each detected voltage from the I / F circuit 11 is A / D converted and taken in as a digital signal, and each digital signal in the same divided range is supplied to the trimming setting circuit 14 according to the trimming mode. Then, the optimum subject brightness is calculated to determine the exposure value, and a signal for writing information on the trimming mode to the film is output.

FIG. 3 is a schematic configuration diagram of an optical system of a single-lens reflex camera in which the photometric system of this embodiment is adopted. The light flux from the subject that has passed through the taking lens 16 in the camera body 15 is 45 behind the taking lens on the optical axis 0.
The movable reflecting mirror 17, which is obliquely installed at an angle of degrees, reflects upward during observation, and forms the subject image on a screen mat 18 arranged above the reflecting mirror 17. The subject image is confirmed by a pentaprism 19 and an eyepiece lens 20 arranged above the screen mat 18.

In this embodiment, the eyepiece lens 20 is used.
By the half mirror 21 that is installed at an angle of 45 degrees just before
The light flux from the screen mat 18 reflected by the pentaprism 19 is split. That is, the screen mat 18 is formed by the half mirror 21.
A part of the luminous flux of passes through the eyepiece lens 20 and goes straight, but the rest is reflected upward. The reflected light flux passes through a photometric optical system (hereinafter referred to as AE optical system) 22 arranged above the half mirror 21 and irradiates the divided AE sensor 12 arranged above the photometric optical system 22. To be done. Here, the subject brightness in each of the three divided areas is measured. The light flux reaching the eyepiece lens 20 is the light flux from the superimposing light source 23 disposed below the half mirror 21 and the light flux that has passed through the half mirror 21. Further, in the image in the finder, in the trimming mode, the image other than the trimming range is whitened by superimposing so that only the image in the trimming range can be seen, and the transmission image outside the trimming range transmitted through the half mirror 21 cannot be seen. Has become.

In the trimming mode, as shown in FIG. 4, <normal> → <wide> → <half> →
It is set by scrolling in a loop in the order of <1/2> → <1/4> to → <Normal> again, and only the selected mode is displayed on the mode display. However, at the time of initialization, the normal mode is set.

FIG. 5 shows an example of a trimming range in each trimming mode and weighting coefficients s, b, a of each block range S, B, A of the AE sensor 12 for each trimming mode. In the normal mode trimming range 24a, the entire image frame of the camera, which is a normal size, is printed, and the weighting coefficient is s = 1, b.
= 1 and c = 0.8 are set. As the trimming range 24b in the wide mode, a range narrowed up and down until it touches the circle of the partial photometric range B for the panorama size is printed, and the weighting coefficient is s = 1, b =
1, a = 0.7 is set.

The half mode trimming range 24
As for c, a range in which the left and right sides are narrowed until it touches the circle of the partial photometric range B for half-size printing is printed, and the camera can be photographed in the horizontal position to print in the half-size vertical position. s = 1, b = 0.
8, c = 0.5 is set. The trimming range 24d in the 1/2 mode is a range in which the image frame is narrowed to 1/2 with respect to the center of the image frame in correspondence with the 2 × zoom.
As the weighting factors, s = 1, b = 0.6, c =
0.3 is set. 1/4 mode trimming range 2
In 4e, a range in which the image frame is narrowed to ¼ with respect to the center of the image frame is printed for 4 × zoom, and the weighting factors are s = 1, b = 0.4, and c = 0. Is set.

Next, FIG. 6 shows a flow up to the setting of the exposure information, and how the weighting for each trimming mode is set until the optimum subject brightness is calculated for each trimming mode. This is mainly shown by a flow chart. First, the sequence starts at step S31 and proceeds to step S32. Step S
In 32, information such as each setting flag is initialized, and the process proceeds to step S33. In step S33, the strobe mode / trimming mode is set. Strobe mode is <Low brightness automatic flash> → <Forced flash>
→ <Stop emitting light again> → <Low brightness automatic light emission>
Each mode is scrolled in a loop and set. However, at the time of initialization, the low brightness automatic light emission mode is set. In addition, the trimming mode is shown in FIG.
As shown in, scrolling is set in the order of each mode in a loop. When the strobe mode and trimming mode have been set, the process proceeds to step S34. In step S34, the three divided ranges S,
The spot photometric value Vs, the partial photometric value Vb, and the peripheral photometric value Vc at B and A are read, and the process proceeds to step S35.

In step S35, a jump is made to a weighting subroutine. ⊚ FIG. 7 shows the weighting subroutine. In the same weighting subroutine, depending on the setting of the trimming mode in step S33 of the flowchart shown in FIG.
In step 4, the photometric values of the AE sensor 12 are used. First, the weighting subroutine is started in step S101, and the process proceeds to step S102. In step S102, it is determined whether the trimming mode is set to the wide mode. If the wide mode is set in step S102, the process proceeds to step S103, the weighting coefficients in the wide mode are set to s = 1, b = 1, a = 0.7, and the process proceeds to step S104.

Next, in step S104, in order to determine the backlight in step S40 of the flow chart shown in FIG. 6, the weighted backlight determination spot photometric value Sv of the spot photometric range S and the same spot photometric range are used. A weighted backlight determination peripheral photometric value Av in a range other than S (the partial photometric range B and the peripheral photometric range C) is set. In step S104, the backlight determination spot photometric value Sv and the backlight determination peripheral photometric value Av are Sv = V.
s × s and Av = Va × a + Vb × b are set, and the process proceeds to step S116. If the wide mode is not set in step S102, the process proceeds to step S105.

In step S105, it is determined whether the trimming mode is set to the half mode. If it is the half mode in step S105, step S1
06, the weighting factor in the wide mode is s = 1,
b = 0.8 and a = 0.5 are set, and step S107
Proceed to. In the same step S107, the backlight determination spot photometric value Sv and the backlight determination peripheral photometric value Av are Sv = Vs.
Xs, Av = Va × a + Vb × b are set, and the process proceeds to step S116. If it is not the half mode in step S105, the process proceeds to step S108.

In step S108, it is determined whether the trimming mode is set to the 1/2 mode. In step S108, if the 1/2 mode, step S1
09, the weighting coefficient in the 1/2 mode is s = 1,
b = 0.6 and a = 0.3 are set, and step S110
Proceed to. In the same step S110, the spot photometric value Sv for backlight determination and the peripheral photometric value Av for backlight determination are Sv = Vs.
Xs, Av = Vb × b is set, and the above step S1 is performed.
Proceed to 16. If it is not the 1/2 mode in step S108, the process proceeds to step S111.

In step S111, it is determined whether the trimming mode is set to the 1/4 mode. In step S111, if the 1/4 mode is selected, step S1
12, the weighting coefficient in the 1/4 mode is s = 1,
b = 0.4 and a = 0 are set, and the process proceeds to step S113. In the same step S113, the backlight measurement spot photometric value Sv and the backlight determination peripheral photometric value Av are Sv = 0, Av.
= 0 is set, and the process proceeds to step S116. If it is not the 1/4 mode in step S111,
It proceeds to step S114.

In step S114, the weighting factors in the normal photographing mode are set to s = 1, b = 1, a = 0.8, and the process proceeds to step S115. In the same step S115, the spot photometric value Sv for backlight determination and the peripheral photometric value Av for backlight determination are Sv = Vs × s, Av = Va × a + Vb ×
b is set, and the process proceeds to step S116. In step S116, the weighted corrected subject brightness Ev in the trimming mode range is set. The same brightness Ev is obtained by dividing the AE sensor 12 into three ranges S,
An arithmetic expression Ev = Vs × s + Vb × b + Va in which the spot photometric value Vs, the partial photometric value Vb, and the peripheral photometric value Vc of B and A are multiplied by the weighting factors s, b, and a, and each term is added.
Calculated from xa. Then, the process proceeds to step S117. The weighting subroutine is ended in the same step 117, and step S3 of the flowchart shown in FIG.
Return to 5.

Now, returning to FIG. 6, step S35.
When the process returns from the weighting subroutine in step S36, the process proceeds to step S36. Then, again in step S36, the process jumps to the strobe mode determination subroutine. here,
The strobe mode determination subroutine shown in FIG. 8 will be described. In step S201, the strobe mode determination subroutine starts, and the process proceeds to step S202. In step S202, it is determined whether or not the strobe light emission stop is set in step S33 of the flowchart of FIG. In step S202, if strobe emission stop is not set, step S2
03, set the flash emission flag FS and FS =
1 (strobe light emission enabled), the process proceeds to step S205. In step S202, if strobe light emission stop is set, the process proceeds to step S204, FS = 0 (strobe light emission prohibition) without setting the same strobe light emission flag FS, and the process proceeds to step S205. In step S205, the strobe mode determination subroutine ends, and the process returns to step S36 in the flowchart of FIG.

Referring again to FIG. 6, step S36.
When the process returns from the strobe mode determination subroutine, the process proceeds to step S37. In step S37,
It is determined whether or not the weighted corrected subject brightness value Ev in the set trimming range is lower than the predetermined brightness value E0, and if Ev <E0, then in step S3.
Go to 8. In step S38, it is determined whether or not strobe light emission is permitted, and if strobe light emission is permitted, the process proceeds to step S39. In step S39,
Flash emission is set and the process proceeds to step S44. If the flash emission is not permitted in step S38, the process proceeds to step S43. In step S37, if the low brightness Ev <E0 does not hold and the brightness is not low, the process proceeds to step S40.

In step S40, the above-described backlight determination is performed. That is, with respect to the backlight determination peripheral luminance value Av as the luminance around the trimming range, the backlight determination spot luminance value S as the luminance near the center of the trimming range.
It is determined whether or not v has a relationship of Av-Sv ≧ Ej with reference to the predetermined backlight luminance value Ej. In this step S40, if it is determined that the backlight is not backlight because the vicinity of the center is not so dark and the relationship Av-Sv ≧ Ej is not established, the process proceeds to step S43.
In the same step S40, the area near the center becomes dark Av-S
If the relationship of v ≧ Ej is established and it is determined that the backlight is present, the process proceeds to step S41.

In step S41, it is determined whether or not strobe light emission is permitted. If the strobe light emission flag FS is set to FS = 1 and strobe light emission is permitted, the process proceeds to step S39. In the step S39, the stroboscopic light emission is set as described above, and the process proceeds to the step S44. In step S41, if the strobe light emission flag FS is not set to FS = 1 and strobe light emission is not permitted, the process proceeds to step S42.

Next, in step S42, the weighted corrected subject brightness value Ev of the entire trimming range is backlit corrected. In the backlight correction, the weighted corrected subject brightness value Ev of the entire trimming range is reduced to approach the weighted corrected subject spot brightness value Sv near the center, and it is determined that the vicinity of the center is dark. Make up for underexposure in the vicinity. Therefore, a brightness value obtained by subtracting the backlight correction predetermined brightness value Eh from the weighted brightness value Ev is newly set as the backlight correction brightness value Ev, that is, Ev = Ev-Eh, and step S4 is performed.
Go to 3. Finally, in step S43, the shutter speed and the aperture value are set by the brightness value Ev set under each condition, and the process proceeds to step S44. In step S44, this sequence ends.

As shown in this embodiment, it is possible to calculate the optimum exposure value by using the AE sensor that does not correspond to the angle of view for trimming in a one-to-one manner. And in this embodiment,
Although the three-division AE sensor is used as the AE sensor, the number of divisions may be plural. Although the exposure value is determined before entering the shutter sequence, it may be used for real-time integration (direct photometry).

[0028]

As described above, according to the present invention, although the multi-segment AE sensor does not completely match the trimming range, the brightness of each segment of the multi-segment AE sensor is adjusted to the trimming mode. By weighting each divided range corresponding to, the brightness value of the entire trimming range suitable for each trimming mode can be automatically calculated, and therefore, the optimum exposure value for the angle of view of trimming can be obtained. Can be set.

[Brief description of drawings]

FIG. 1 is a conceptual diagram of the present invention.

FIG. 2 is a block configuration diagram of a camera photometric system showing an embodiment of the present invention.

FIG. 3 is a schematic configuration diagram of a single-lens reflex camera to which the photometric system is applied.

FIG. 4 is a diagram showing a setting order of trimming modes in the above embodiment. .

FIG. 5 shows the trimming modes in the above embodiment,
The figure which showed the trimming range on an AE sensor and the weighting factor of each division range.

FIG. 6 is a flowchart showing the operation of the photometric system of the above embodiment.

7 is a flowchart showing the operation of a weighting subroutine in the flowchart of FIG.

8 is a flowchart showing an operation of a strobe mode determination subroutine in the flowchart of FIG.

[Explanation of symbols]

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Claims (1)

[Claims] 1. A shooting mode switching means for appropriately switching between a normal shooting mode and a trimming shooting mode for designating to print an area narrower than the area printed in the normal shooting mode, and a printing range for the normal shooting mode. Divided light metering means for dividing the light into a plurality of blocks for photometry, weighting changing means for changing the weighting between the plurality of blocks corresponding to the photographing mode switching means, and the division based on the output of the weighting changing means. A photometric system for a camera, comprising: a computing unit that computes subject brightness using an output from the photometric unit.