JPH02251941A - Electronic camera - Google Patents

Abstract

PURPOSE:To indicate whether or not stroboscopic light is enough in quantity to obtain proper exposure by displaying a warning when it is decided that the quantity of light is deficient. CONSTITUTION:A system controller 21 detects the 1st stroke, etc., of a release button 22 to check the source voltage of a battery 23 and further initialize a disk at need, and a sensor 24 evaluates external brightness, etc., and sends a charging start signal to a stroboscopic circuit 2 when judging that the external brightness is dark, thereby starting stroboscopic charging operation. Further, a distance measurement system 3 measures the distance to a subject and those results are displayed on display devices 7 and 8 as 'warning display 1' and 'warning display 2'. Consequently, it is indicated whether or not the stroboscopic light is enough in quantity to obtain proper exposure.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Application of the Invention) The present invention relates to an electronic camera, and particularly to control when photographing using strobe light.

(Background of the Invention) In recent years, electronic cameras with an externally attached or built-in strobe device have been announced, and the use of the strobe device is useful in widening the range of subjects that can be photographed.

However, strobe light naturally has a small light source,
Therefore, as the distance increases, the darkness increases in inverse proportion to the square of the distance, so for electronic cameras with a smaller dynamic range (narrow latitude range) compared to silver halide cameras,
The problem of underexposure is likely to occur.

(Object of the Invention) A first object of the present invention is to provide an electronic camera that can notify whether or not the amount of strobe light is sufficient to obtain proper exposure.

A second object of the present invention is to provide an electronic camera that achieves the first object and can increase opportunities to provide proper exposure without any troublesome operations when the amount of light is insufficient.

(Features of the Invention) In order to achieve the first object, the present invention provides a determination method for determining whether or not a subject can be sufficiently illuminated with strobe light during strobe photography in a set shooting mode. and a display means for issuing a warning when the determination means determines that insufficient light quantity will occur, so that when the subject cannot be sufficiently illuminated, a display means is provided to issue a warning to that effect. It is characterized by the fact that it is made to do.

Furthermore, in order to achieve the second object, the present invention provides sufficient illumination of a subject with strobe light when performing strobe photography when the set photography mode is other than the photography mode for the highest sensitivity setting. a discriminating means for discriminating whether or not a light quantity shortage will occur; , a photographic sensitivity control means that automatically increases the photographic sensitivity, so that the subject cannot be sufficiently illuminated with the strobe light (this is determined based on the subject distance information or the dimming output when the strobe is fired). ), we will issue a warning to that effect, automatically increase the shooting sensitivity (by switching the shooting mode from frame to field, increasing the gain of the image signal, changing the characteristics of the optical filter, etc.), and reduce the possible shooting distance. It is characterized by being extended as long as possible.

(Embodiments of the Invention) Hereinafter, the present invention will be described in detail based on illustrated embodiments.

FIG. 1 is a block diagram of an electronic camera showing an embodiment of the present invention.

In FIG. 1, 1 is a strobe light emitting tube, 2 is a strobe circuit with functions of charging, emitting, and stopping flashing, 3 is a ranging system, 4.5 is a finder optical system for a user 6,
7.8 is a display (LED next to the finder), 9 is a drive circuit for the displays 7 and 8, 10 is a lens, 11 is a focus adjustment system that drives the lens 1o, 12 is an aperture, and 13 is an aperture drive circuit. , 14 is a shutter, 15 is a shutter drive circuit, 16 is an image sensor, 17 is a signal processing circuit that converts the sensor output into a signal suitable for recording, 18 is an image sensor 16. 19 is a disk drive circuit; 2o is a drive system including a head feed, spindle motor drive circuit, etc.; 21 is a system controller; 22 is a release button; 23 is a battery that serves as a power source for the entire system, and 24 is a sensor for detecting external data such as photometry and colorimetry.

Next, the operation will be explained.

Regarding the general operation of the camera, upon detection of the first stroke of the release button 22, the system controller 21 checks the power supply voltage of the battery 23, initializes the disk if necessary, and further detects the external brightness using the sensor 24. If it is determined that the external brightness is dark, a charging start signal is sent to the strobe circuit 2 to start strobe charging. Further, the distance to the subject is measured by the distance measuring system 3. These results are then displayed on the display 7.8.

The user 6 checks the viewfinder optical systems 4, 5 and the display 7.8 and performs the second stroke operation of the release button 22.

Then, the system controller 21 drives the lens 10 to a position corresponding to the distance measured in advance by the focus adjustment system 11, and removes the calibration 12 from the aperture drive circuit 1.
3, the image sensor 16. The signal processing circuit 17 is activated via the timing signal generation circuit 18, and then the shutter 14 is driven by the shutter drive circuit 15.

The optical image at this time is converted into an electrical signal by the image sensor 16, further converted into a signal suitable for recording by the signal processing circuit 17, and recorded on a disk (not shown) by the disk drive circuit 19.

In the photographing process, when the strobe device is necessary and usable, the strobe circuit 2 triggers the arc tube 1 when the shutter is driven, and when the sensor 24 determines that the required amount of light has been reached, the strobe circuit 2 triggers the flash tube 1. Stop the emission of light from the arc tube 1.

Next, the configuration of the strobe circuit 2 will be explained using FIG. 2.

In FIG. 2, 101 is an oscillation circuit, and a charging start signal 1
When it receives 10, it oscillates, transformer 102, diode 1
03 to start charging the main capacitor 104.

105 is a light emission control circuit that controls light emission and stop of light emission;
This is known as a general dimming strobe, and a light emission start signal 112 and a light emission stop signal 113 are sent from the system controller 21. 106 is a diode that detects the peak voltage during oscillation (the charging voltage of main capacitor 104), and 107 is a capacitor that converts this to DC. 10
8.109 is a voltage dividing resistor that appropriately divides this voltage, and this divided voltage is sent to the system controller 21 as a detection level signal 111.

Here, if the guide number of the strobe device (with respect to the standard usage of the image sensor used) is Go and the open FNO of the lens is Fo, then the distance D = G / F
Sufficient illumination can be provided up to o.

In addition, by changing the sensor readout mode, that is, the shooting mode from frame to field, it is possible to use frame type sensors in the field.
Assuming that the sensitivity can be increased by 8 times by increasing the gain of the signal processing system, D = G / F o
The light can be adjusted up to X r d x FW.

Figure 3 shows that in a system where M = 1.2 and S = 1 to 4, when dimming is possible with M = S = 1, "No display J, M,
An example of a camera is shown in which a warning display is displayed when dimming is possible by increasing S. If dimming is not possible by increasing IJ, M, and S, a warning display 2 is displayed.

First, the distance to the subject is determined by the distance measuring system 3.

Then D≦G o / F o , i.e. S=M=1
When the distance is sufficiently close, S=M=1 and both indicators 7.8 are turned off. At this time, when the distance is sufficiently small, the adjustment accuracy is improved by making F a little larger, as shown in #4 to #7.

If D<G○/　F　o, the amount of light is insufficient.

Therefore, M=2. S=4, that is, the sensitivity is increased by 8 times (2X4
). If it is still dark, that is, D>rth x G
In the case of o/F o, only the display 8 is turned on (corresponding to "warning display 2"), M=23=4 and FNO is set to Fo (open FNO).

In the middle, that is, G○/ F o < D ≦ F x G
○/In the case of F o, only the display 7 is turned on (corresponding to "warning display 1"), and one or both of S and M is controlled. Thereby, insufficient light amount can be prevented. In this example, when it is less than 2 times, M = 1, so when S = 1 to 22 times or more, M = 2, and therefore S = 1 to 4.
Necessary corrections are made as shown in Figure 4. Therefore, it is possible to accurately control light up to a distance of 8 times in total, that is, 1 time (approximately 3 times).

According to this embodiment, by using the AP system originally provided for focus adjustment, that is, by using subject distance information, it is determined whether the strobe light emission amount is appropriate,
Since the results are displayed, the user can be informed whether or not the amount of light is insufficient. In addition, since sensitivity correction is automatically performed when the amount of light is insufficient, it is possible to significantly reduce shooting errors caused by insufficient strobe light emission due to a long distance to the subject.

(Correspondence between invention and actual example) In this embodiment, # in the sequence controller 21 is
The part that performs the operation #2 is the determining means of the present invention, and the part that performs the operation #11. #
The part that performs the operation of 17 and the display 7.8 serve as display means,
#13. #14. The portion that performs the operation #18 corresponds to the photographic sensitivity control means.

(Modification) In this embodiment, M or S is corrected according to the distance, but in reality, the storage of the image sensor 16, that is, the strobe light emission, and the readout are not simultaneous, so at least one of M and S is corrected. It may be calculated from the light control sensor output, and in this case, the calculation can include the reflectance of the subject.

However, in this case, care must be taken because the time from detection to control and readout is short.

In addition, in this example, D=r D
Although the warning display is performed based on whether or not the voltage is low, the under voltage display may be performed with a tolerance of about 0.5V, for example, from D=f/G o / Do.

Furthermore, in this embodiment, a case has been described in which recording is performed on the disk at the same time as reading from the image sensor 16, but in a system having a buffer such as a so-called semiconductor memory, there is a possibility that a signal is insufficient during reading (or afterward). It is also possible to detect this and correct it (by increasing the gain or by increasing the gain and using a low-pass filter).

In addition, regarding gain correction, etc., even in the case of so-called AE, by evaluating the amount of light at the same time as the accumulation in the sensor, it is possible to make more accurate corrections than by using prior information, which is generally done. be.

Furthermore, in this embodiment, in order to increase the sensitivity, the image sensor usage mode is changed (switching between frame shooting mode and field shooting mode) and the gain of the image signal is increased, but the invention is not limited to this. Instead, the sensitivity may be increased by, for example, changing the characteristics of the optical filter or moving part or all of the optical filter out of the photographing optical path.

Furthermore, in this embodiment, the shooting sensitivity is automatically increased when the amount of light is insufficient, but this is not limited to this, and the warning display may be used to prompt the photographer to increase the sensitivity. For example, the use mode of the image sensor may be switched from frame to field. In this case, the photographer must display the warning (
The user will continue to increase the photographic sensitivity as much as possible until this warning display (which may be displayed using a sound or the like) disappears.

(Effect of the invention) As explained above, according to the present invention as set forth in claim 1,
When taking flash photography in the set shooting mode,
The camera is equipped with a determining means for determining whether or not a subject can be sufficiently illuminated with strobe light, and a display means for issuing a warning when it is determined by the determining means that an insufficient amount of light will occur. Therefore, if the subject cannot be adequately illuminated, a warning will be issued to that effect.
It becomes possible to inform whether or not the amount of strobe light is sufficient to obtain proper exposure.

Further, according to the present invention as set forth in claim 2, it is possible to sufficiently illuminate the subject with strobe light when performing strobe photography when the set photography mode is other than the photography mode for setting the highest sensitivity. a discriminating means for discriminating whether the amount of light is insufficient; a display means for issuing a warning when the discriminating means determines that a light amount shortage will occur; It is equipped with a photographic sensitivity control means that increases photographic sensitivity, and if the subject cannot be sufficiently illuminated with strobe light,
In addition to giving a warning to that effect, the shooting sensitivity will be automatically increased.
Since we have extended the shooting distance as much as possible, we can tell you whether or not the strobe light has enough light to obtain the proper exposure, and if the light is insufficient, you can set the correct exposure without having to perform any troublesome operations. It becomes possible to increase opportunities to provide

[Brief explanation of drawings]

FIG. 1 is a block diagram showing an embodiment of the present invention, FIG. 2 is a circuit diagram showing an example of the configuration of the strobe circuit shown in FIG. 1, FIG. 3 is a flow chart showing the operation of this embodiment, and FIG. It is a figure which shows an example of sensitivity correction in a present Example. 2... Strobe circuit, 3... Ranging system, 7.8... Display unit, 16... Image sensor, 17... Signal processing circuit, 21.
...System controller, 24...Sensor.

Claims (2)

[Claims] (1) In an electronic camera having a plurality of shooting modes for different sensitivity settings, a determination means for determining whether or not a subject can be sufficiently illuminated with strobe light during strobe photography in the set shooting mode; , If it is determined by the determination means that insufficient light amount occurs,
An electronic camera equipped with a display means for issuing such a warning. (2) In an electronic camera that has shooting modes for multiple different sensitivity settings, when shooting with a strobe when the shooting mode set is not the shooting mode for the highest sensitivity setting, the subject is sufficiently illuminated with strobe light. a discriminating means for discriminating whether or not the amount of light can be reduced; a display means for issuing a warning when the discriminating means determines that insufficient light quantity will occur; and a display means for issuing a warning when the display means issues a warning is an electronic camera equipped with a photographic sensitivity control means that automatically increases photographic sensitivity.