JPH01217431A - Photometric device - Google Patents

Abstract

PURPOSE:To enable a user to correctly execute exposure correction as the user desires in case of executing the correction by automatically switching a multipattern photometric system to an average photometric system or a center part priority average photometric system when an exposure correcting means is manually operated and setting up a value obtained by adding an exposure correction value to a photometric value as an exposure value. CONSTITUTION:When an exposure correcting means 38 is manually operated in case of correcting exposure in accordance with a photographing purpose to execute photographing, the multipattern photometry is automatically switched to average photometry or center part priority average photometry. Since an uncorrected reference photometric value is displayed on a finder 40 or the like, required correction can be executed based on the displayed photometric value, a value obtained by adding a correction value to the average photometric value or the center part priority average photometric value goes an exposure value. Consequently, the generation of malfunction can be prevented and optional correction can be surely executed.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a photometric device for use in cameras such as electronic still cameras, silver halide cameras, and video cameras.

[Prior Art] Modern camera photometers, for example, built into a 35 mm reflex camera, divide the shooting screen into multiple areas and measure each area separately. The maximum brightness value, minimum brightness value, average brightness value, and brightness difference (
By detecting the maximum brightness value - minimum brightness value), etc., and calculating the correction value from the average photometry value and center-weighted average photometry value and adding it to this, manual correction operations can be performed under normal shooting conditions. There are devices that perform multi-pattern metering that automatically obtains the correct exposure without any additional exposure.

However, for example, in a scene with a white wall in the background and daffodils arranged in a narrow vase, the brightness difference is hardly noticeable, and the correction value is almost 0, making it impossible to shoot with the average photometric value or the center-weighted average photometric value. The drawback was that the result was underexposure. In order to solve this drawback, for example, there is a method described in Japanese Patent Laid-Open No. 57-82822. This is so that when the luminance difference is smaller than a certain value, a predetermined correction value is added to the selected photometric value.

[Problem to be solved by the invention]

However, the correction in the photometric device described in JP-A-57-82822 is to further correct the photometric value selected in multi-pattern photometry, and the photometric value to be corrected is The photographer has no idea whether the value is a partial photometered value or how much correction has been made from the average photometry value. Therefore, it is not possible to determine how much correction should be made to obtain the desired reproduction result. Therefore, for example, in a backlit scene, a positive correction often results in double correction, resulting in overexposure.

[Purpose of the Invention] The present invention has been made to solve the above-mentioned problems, and although the multi-pattern photometry method is normally used, it is possible to make exposure compensation as desired by the user without making any mistakes. The purpose is to provide a photometric device that can perform

[Single step to solve problems]

In order to achieve the above object, the photometry device of the present invention automatically switches from a multi-pattern photometry method to an average photometry method or a center-weighted average photometry method when the exposure compensation means is manually operated, The apparatus is equipped with an arithmetic processing means that determines, as an exposure value, a value obtained by adding an exposure correction value by an exposure correction means to a part point average photometric value. Further, in order to allow the photographer to accurately grasp the state in which the above-mentioned exposure correction processing is being performed, a display device such as a display device in the viewfinder or a liquid crystal display panel is provided.

[Function] According to the above configuration, when the user manually operates the exposure compensation means when he or she wants to take a picture with exposure compensation according to the shooting intention, multi-pattern photometry is automatically switched to average photometry or center-weighted average photometry.

Therefore, the photometric value displayed in the viewfinder etc. is the uncorrected standard photometric value, so you can make desired corrections based on this, and you can use the average photometric value or center-weighted photometric value. The exposure value is the average metered value plus the correction value.

Embodiments of the present invention will be described in detail below with reference to the drawings.

〔Example〕

In FIG. 1 showing a block diagram of a photometric device of the present invention and an optical system of an electronic still camera 1 incorporating this photometric device, the optical system of the electronic still camera 1 has two groups (lenses 10a and 10a).
, 10b) configuration, and an instantaneous diaphragm 11 arranged between the lens 10a and the lens 10b.
．． Quick return movable mirror 12. Focusing screen 13. Condenser lens 14. Pentaprism 15. Consists of 16 eyepieces, 1 pentaprism
Behind 5 are 9 SPDs via Fresnel lens 17.
Photometric sensor 1 consisting of (silicon photodiode)
8 is placed. Further, behind the movable mirror 12, a CCD 21 for imaging is arranged via a focal plane shutter 22.

The nine SPDs constituting the photometric sensor 18 are arranged as shown in FIG.
It is connected to the CPU 26 via a converter 19.

A program ROM 24 is connected to this CPU 26, and is operated according to a sequence program written therein.

Further, the CPU 26 is connected to the diaphragm 11 and the shutter 22, and when the release switch 35 is turned on, the diaphragm 11 is instantaneously stopped down based on the exposure value P calculated from the photometric data, and at the same time the shutter 22 is opened and closed. CCD2
Exposure is given to 1.

An exposure correction button 38 is connected to the CPU 26, and correction data for correcting the exposure value P is input to the CPU 26. When this exposure compensation button 38 is pressed once, +1
The correction amount changes by 1/2EV in the range of +2EV to -2EV depending on the number of times the button is pressed, such as /2EV and +IEV when pressed twice, and is canceled each time one exposure is completed. Furthermore, the CPU 26 is connected to an LED installed in the lower part of the finder 40 via an LED driver.
41 is connected.

A signal processing circuit 30 is connected to the CCD 21, and this signal processing circuit 30 converts a still video floppy (hereinafter referred to as
It is connected to a magnetic head 34 for writing video signals onto a video floppy (referred to as a video floppy) 33. The video floppy 33 is rotated at a constant speed by a motor 36.
This motor 36 has a driver 3 for driving it.
7 is connected. Further, the driver 37 and head amplifier 32 are connected to the CPU 26.

Further, a CCD drive circuit 29 for driving the CCD 21 is connected to the CCD 21.
A synchronizing signal generating circuit 28 is connected to. This synchronization signal generation circuit 28 is also connected to the CPU 26,
Various pulses necessary for driving the CCD 21 are synchronized with each other, and a master clock pulse for controlling the sequence of the C'P U 26 is generated.

Incidentally, FIG. 2(b) shows an arrangement pattern of SPDs constituting a photometric sensor in another embodiment.

Next, the operation of the photometric device of the present invention configured as above will be explained. First, when the video floppy 33 is loaded into the electronic still camera 1 and the power is turned on, a master clock pulse is sent from the synchronizing signal generating circuit 28 to the CPU 26°ccDi[M circuit 29, and respective drives are started. A signal is sent from the CPU 26 to the driver 37 to drive the motor 36, and the loaded video floppy 33 begins to rotate, reaching a steady rotation speed of 60 revolutions per second in about 30 m5.

When the photographic lens 10 is directed toward a subject, an optical image of the subject captured by the photographic lens 10 is reflected by a movable mirror 12 and formed on a focusing screen 13. This formed object image is condensed by a condenser lens 14 and observed by a photographer through a 15° pentaprism eyepiece 16. On the other hand, a part of the optical image of the subject is guided by the Fresnel lens 17 to the photometric sensor 18 and formed into an image.

The optical image formed on this photometric sensor 18 is composed of nine SPs.
After being divided into nine areas by D and each converted into a luminance signal, it is digitized by the A/D converter 19 to become a luminance output P, ~P, which is input to the CPU 26.

The CPU 26 processes the photometric data according to the program sequence of the program ROM 24 shown in FIG.

First, the luminance outputs P, -P are averaged to give an average photometric value EVm.
Calculate ean. Here, if manual correction is not performed, the maximum brightness value EVmax is calculated from the brightness output P, -P9.
, the minimum brightness value EVmin is detected, and this brightness difference (EV
max −E Vmin ) and average photometric value EVmea
An exposure correction value ΔEV obtained by taking n into consideration is added to the average photometric value EVmean to obtain an exposure value P. At this time, an LED in the finder 40 indicates that the correction is in progress.
41 is + if it is a positive correction, - if it is a negative correction.
lights up, and EVmean+ΔEVl is displayed in the lower right corner.
The shutter speed and aperture value will be displayed.

In the case of manual correction, by operating the exposure correction button 38, the exposure correction value ΔEV2 is added to the average photometric value EVmean to obtain the exposure value P. In the finder 40, before manual correction, the average photometric value E
If the exposure is maintained at Vmean, the LED 41 indicating that the correction is in progress will be off, and the EVmean
When exposed at +ΔEV, it is lit + or -. If a + or - is displayed just before manual correction, the + or - will disappear the moment the exposure compensation value ΔE■2 is input, and as shown in Figure 4, in the case of plus correction, +n or - will be displayed. In the case of correction, -n lights up, and the shutter speed and aperture value at EVmean+ΔEV are displayed in the lower right corner. In addition, the code n
indicates the absolute value of the exposure correction value ΔEV2.

Once the main subject is in the center of the viewfinder, activate the AE lock mechanism (not shown) by pressing the release button halfway, memorize the exposure value P, and decide on the composition while observing the viewfinder image. Press the release button (not shown).

As a result, the release switch 35 is turned ON and the movable mirror 12 is simultaneously raised, and immediately after this, the exposure value P
The aperture 11 is narrowed down based on the
is opened and closed. At the next moment, the diaphragm 11 returns to its open state, the movable mirror 12 returns to its original position, and the viewfinder field of view is restored.The optical image, which has been controlled to have an appropriate amount of light, is converted into a video signal by the CCD 21, and the well-known Signal processing circuit 30. The signal is input to the head amplifier 32 via the FM modulation circuit 31. Head amp 32 is C
The magnetic head 34 is operated according to the command from the PU 26, and the C
A video signal read from a CD 21 is instantaneously recorded on a video floppy 33.

Although the above embodiments have been described using the average photometric value as the reference value, it goes without saying that the center-weighted photometric value may be similarly used as the reference value and correction may be applied thereto. Furthermore, the photometric device of the present invention is applicable not only to electronic still cameras.
It can also be used with regular silver halide cameras and video cameras.

[Effects of the Invention] As explained above, according to the photometry device of the present invention, the exposure amount is normally determined by multi-pattern photometry, but when performing manual correction, it automatically determines the exposure amount using average photometry or center area photometry. The camera switches to weighted average metering, and the value obtained by adding the exposure compensation value to this metered value becomes the exposure value. When the photographer performs exposure compensation, he or she can use the average metering value or the center-weighted average metering value as a reference. In addition to being able to correct the
It becomes possible to provide a photometric device that prevents double correction. Furthermore, by installing a display device such as an in-viewfinder display device or a liquid crystal display panel, it becomes possible to clearly display the above-mentioned exposure compensation processing, which prevents erroneous operations and makes it possible to perform arbitrary compensation reliably. .

[Brief explanation of the drawing]

FIG. 1 is a block diagram schematically showing the structure of an embodiment of the present invention. FIG. 2(A) is a schematic diagram showing the photometric area of the embodiment of the present invention. FIG. 2(B) is a schematic diagram showing a photometric area of another embodiment of the present invention. FIG. 3 is a flowchart showing the main part of the sequence program according to the embodiment of the present invention. FIG. 4 is a schematic diagram showing a viewfinder display situation according to an embodiment of the present invention. 1...Electronic still camera 11...Aperture 18...Photometering sensor 21...C0D 22...Shutter 24...Program ROM 26...CPU 40...Finder 41...LED. Figure 2 (a) (b) Figure 4

Claims (2)

[Claims] (1) Divide the shooting screen into multiple parts and measure the light, and from the multiple brightness values obtained, calculate the maximum brightness value, minimum brightness value, average brightness value,
a calculation processing means that detects brightness data such as a brightness difference, performs calculation processing, calculates a correction value, and adds it to an average photometric value or a center-weighted average photometric value to calculate a first exposure amount; and this calculation processing unit exposure compensation means for correcting the exposure amount by manual operation regardless of the first exposure amount determined by the calculation processing means, and the calculation processing means receives the correction data from the exposure compensation means,
A photometry device characterized by canceling the exposure amount and outputting a second exposure amount obtained by adding correction data to the average photometry value or the center-weighted average photometry value. (2) When the difference between the average photometric value or the center-weighted average photometric value and the first exposure amount is equal to or greater than a certain value, the arithmetic processing means displays in the viewfinder that correction is in progress; 2. The photometric device according to claim 1, further comprising display means for displaying in the viewfinder that the correction is in progress when outputting the two exposure amounts.