JPH02294626A - Stroboscopic system for camera - Google Patents

Abstract

PURPOSE:To improve accuracy in dimming control and to accomplish photographing with strobe light at the time of mounting a stroboscope having no dimming sensor by performing the dimming control in consideration of the output from 1st and 2nd dimming sensors at the time of mounting the stroboscope having the dimming sensor and performing the dimming control with the output from the 2nd dimming sensor at the time of mounting the stroboscope having no dimming sensor. CONSTITUTION:Strobe light reflected from an object is integrated and received by the 1st dimming sensor 8 provided in the stroboscope 5 and the 2nd dimming sensor 3 provided in a camera 1. When the received light quantity becomes proper, the stroboscope 5 is controlled to stop light emission with a light emission stop signal transmitted from the camera 1 side through a contact which exists in an accessory shoe 4. In the case of the stroboscope for TTL dimming where the dimming sensor is not provided, dimming and photographing are performed only by the 2nd dimming sensor 3 provided in the camera 1. Thus, dimming control in the case of mounting the stroboscope having the dimming sensor is performed with high accuracy and also photographing with strobe light is executed even in the case of mounting the stroboscope having no dimming sensor.

Description

Detailed Description of the Invention (Field of Application of the Invention) The present invention mainly uses an image sensor (for example, COD, etc.) to
It relates to a system that includes an electronic camera that converts subject light into an electrical signal through photoelectric conversion and records it on a medium such as a magnetic disk, and a strobe that is attached to the camera. (Background of the Invention) Conventionally, external light control method and TTL light control method are known as strobe light control methods for silver halide cameras. The external dimming method is
An external light control sensor is installed in the strobe, and when the light reflected from the subject by the strobe light is received cumulatively over time, and the amount of light received is the appropriate amount determined from the film sensitivity and camera aperture value input to the strobe in advance, the strobe This method stops the light emission.

This method has the advantage of being able to adjust the light without requiring any special equipment inside the camera, but it also creates parallax between the camera and the photographic lens, and since the light receiving angle is constant, the angle of view may change. However, there were disadvantages in that it was difficult to adjust the light with high precision, and the influence of background light was large.

On the other hand, with the TTL light control method, the image projected onto the film is illuminated with strobe light and is metered by a light-receiving element inside the camera, and the reflected light is adjusted to an appropriate level determined from the film sensitivity and camera aperture set in advance on the strobe. This is a method that stops the strobe light emission when this is reached. This method is free from parallax and allows for highly accurate light control because it can adjust the light in response to changes in the angle of view, and is currently the mainstream light control method for single-lens reflex cameras.

However, this method measures the weak reflected light from the film, so differences in reflectance between films may cause errors.
Furthermore, since the method basically receives the reflected light from the object, it is affected by the background depending on the position and size of the object, resulting in problems such as errors.

Furthermore, the most basic light control method is the flashmatic method, which uses distance information obtained from the strobe or camera's distance measuring means to use the strobe's guide number (G
This method determines the aperture value of the camera by dividing the number (NO), and then fires the strobe for a predetermined period of time to obtain the appropriate exposure. This method is not affected by the position and size of the subject, or the condition of the background, and allows for highly accurate light control, but on the other hand, automatic light control requires a highly accurate distance measurement method, especially when the lens focal length is on the short focal length side. , difficult to realize.

Now, in electronic cameras that use an imaging device (CCD) to convert subject light into electrical signals and record them on media such as magnetic disks, the required dimming precision is higher than that of silver halide cameras due to the narrow COD latitude. High precision is required.

For example, in the case of silver halide film (negative), the latitude is ±5EV, whereas in the case of an electronic camera, a dimming accuracy of at least ±IEV is required, although this varies depending on the characteristics of the COD.

In electronic cameras that require such high-precision light control, TTL allows for more precise light control than external light control methods.
When a dimming method is applied, the following two methods can be considered as methods for receiving reflected light.

1) A half mirror is provided in the optical path, and the reflected light is received by a sensor.

2) Receive light reflected from the CCD imaging surface (filter surface).

However, in the case of method 1), placing a half mirror in the photographing optical path reduces the amount of light incident on the CCD imaging surface, lowering the photographing sensitivity, and the space required to arrange the half mirror decreases. This also poses a disadvantage. Furthermore, in the case of 2), the CCD imaging surface originally takes measures such as anti-reflection coating, and the reflected light becomes quite weak, making dimming itself difficult.

In addition, when trying to apply the flashmatic method, the distance measurement accuracy required is stricter on the short focus side and on the far distance side, especially in electronic cameras that frequently use lenses on the short focus side. This is disadvantageous and difficult to achieve.

In addition, with external light control, there are problems such as the occurrence of parallax between the photographic lens and the light control sensor, and the inability of the light receiving angle of the light control sensor to follow changes in the angle of view that occur when the focal length of the photographic lens is changed. However, by adding a parallax correction mechanism linked to subject distance information from the camera's distance measuring device, a light receiving angle control mechanism, etc., higher accuracy can be expected.

By the way, a major advantage of single-lens reflex cameras is that components such as strobes and lenses can be systemized according to the shooting intention, and it is desirable to have compatibility with existing components as much as possible when creating a system. .

However, for single-lens reflex cameras, there are roughly two types of strobes that can be attached to and detached from existing cameras: one is an external flash that has a strobe light emitting part and a light control sensor, and the other is a basic flash that There is a TTL dimming strobe that has only a strobe light emitting section, and the latter type of strobe is now becoming mainstream in silver halide cameras.

In this situation, for the reason mentioned above, when using an external flash control flash (with a light receiving angle control mechanism, etc.), which is considered to be the most suitable light control method for a single-lens reflex electronic camera. , which is currently widely available in the market.
Since the TL dimming strobe does not have a dimming sensor, it is completely unusable, and the user must purchase a dedicated strobe.

Figure 5 shows the correlation between the strobe light control method and the compatibility with strobes as described above. In the figure, it is assumed that the camera has a passive AF device such as a phase difference detection method. The strobe is equipped with an AP auxiliary light irradiation member for shooting low-brightness subjects.

In the figure, in the case of a TTL dimming type silver halide camera, etc., TT
In addition to the L-adjustable strobe (Route A), external dimming strobes can also be used (Route C). In this case (Route C), it is possible to control the strobe emission stop on the camera side through the contact provided on the accessory shoe. If so, TTL
Dimming is possible. Also, in the case of an electronic camera suitable for an external light control type, an external light control flash can of course be used (route b), but T
In the case of the TLH optical strobe (route d), there was a problem that the light could not be adjusted because neither the camera nor the strobe had a light control sensor. C) An object of the present invention is to perform dimming control with higher precision when a strobe having a dimming sensor is attached, and to provide a method for controlling the dimming when a strobe that does not have a dimming sensor, which exists in large quantities on the market, is attached. To provide a camera/strobe system capable of performing strobe-treated shadows even in the case of

(Features of the Invention) In order to achieve the above object, the present invention provides a strobe having a first light control sensor having a different light receiving angle from a second light control sensor disposed on the camera side, and a second light control sensor disposed on the camera side. In strobe photography when a strobe having a light sensor and the first light control sensor is attached, light control is performed based on the outputs of the first light control sensor and the second light control sensor. When a strobe without a light sensor is attached, it is equipped with an electronic camera having a dimming control means for controlling the dimming based on the output of the second dimming sensor on the camera side. When a strobe with a light sensor is attached, the light control is performed by considering not only the output of the first light control sensor, which can be expected to provide accurate light control, but also the output of the light control sensor on the camera side. The present invention is characterized in that when a strobe without a light control sensor is attached, light control is performed using the output of the light control sensor on the camera side.

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

FIG. 1 shows the configuration of an embodiment of a camera and a strobe according to the present invention.

In the figure, 1 is a camera, 2 is a photographic lens, 3 is a first light control sensor, and 4 is an accessory shoe. 5 is TT
This is a strobe for L dimming, and has a light emitting unit 6, an AP auxiliary light illumination member 7, and a second dimming sensor 8 having a light receiving angle different from that of the first dimming sensor 3, and an accessory shoe 4.
In the case of a strobe light control connected to the camera 1 via the flash light control, the light reflected from the subject is reflected by the first light control sensor 8 provided on the strobe 5 and the second light control sensor 3 provided on the camera 1. When the cumulative amount of light received reaches the appropriate amount, the strobe 5 is controlled to stop emitting light by a light emitting stop signal sent from the camera 1 through a contact (not shown) located on the accessory shoe seat (details will be described later). Further, if the strobe is for TTL flash control without a light control sensor, light control photography is performed only by the second light control sensor 3 provided in the camera 1.

The configuration of the camera 1 and strobe 5 described above is shown in Figure 2.
The same parts as in FIG. 1 are given the same reference numerals.

In FIG. 2, 9 is an exposure control mechanism, 10 is a CCD, 1
1 is a signal processing circuit, 12 is a recording circuit, 13 is a control circuit,
14 is the interface between strobe 5 and camera 1, 15
1 is a photometric sensor, 16 is a photographing lens information reading device, 1
Reference numeral 7 denotes a light projection and light emission angle correction mechanism for the light emitting unit 6 and the first dimming sensor 8.

FIG. 3 shows the light receiving angles of the first and second light control sensors (8.3) as light receiving ranges A and B on the screen. Here, the light receiving range A of the first dimming sensor 8 is automatically adjusted by the light emitting and receiving angle correction rock 17 in the strobe 5 so that it becomes roughly spot-like based on the lens focal length and distance measurement information. . However, if the light receiving angle of the second photochromic sensor 3 is constant, the light receiving range changes as the focal length of the photographic lens 2 changes and is not constant. As shown in FIG. 3B, the light receiving range at 12 mm) is set to be larger than the spot dimming range A to enable average photometric dimming.

Next, we will explain the signal flow using Figure 2. In strobe photography, when the control circuit 13 determines that strobe light is necessary based on the output of the second light control sensor 3 provided in the camera 1, first, the focal length information of the photographic lens 2 is read by the photographic lens information reading device. 16 into the control circuit 13, and the light emitting and reception angle correction mechanism 17 of the attached strobe 5 respectively (light emitting unit 6 and first
The angle of view of the dimming sensor 8) is adjusted. After that, when the release signal is given to the control circuit 13,
The control circuit 13 operates the exposure controller 9 such as a lens shutter, and also operates the light emitting part 6 of the strobe 5 at a predetermined timing.
0 emission instruction. The strobe light reflected by the subject from the light emitting unit 6 is received by the first and second light control sensors, and when the amount of light received by both reaches a predetermined amount, the control circuit 13 outputs a light emission stop signal. Exposure control is complete. The light control by the first and second light control sensors is basically performed by the first light control sensor 8 when using a dedicated strobe as described later. The dimming reference amount of the first dimming sensor is corrected according to the output difference of the dimming sensor. The subject image received by the CGD 10 is processed into a predetermined signal by the signal processing circuit 11.
The recording circuit 12 records on a medium such as a magnetic disk.

FIG. 4 is a flowchart showing operations during dimming control. The operations #1 to #6 in FIG. 4 are as described above.

As mentioned above, when the dedicated strobe 5 is attached (#7>, the light control is basically performed by the output Vs of the first light control sensor 8, and after the strobe fires, the first and second The outputs Vs and Va of the dimming sensors are cumulatively received, and at a predetermined timing, the output difference Vd (=Vs-Va
), and based on the difference, the first
Determine the dimming reference amount Vk of the dimming sensor 8 (Vk=f (
Vd)) (#8~#-1 1) . For example, if there is an extremely reflective object in the background, the value becomes Vs(Va (see Figure 3)), and the Vs value itself becomes an excessive value.
By setting the dimming reference amount Vk to a negative value according to (Vs-Va), accurate dimming is possible while suppressing the influence of the background, so the cumulative amount of light received by the first dimming sensor 8 is When the value becomes equal to Vk, the light emission is stopped (#12) and the exposure is completed (#13-116).

On the other hand, when using a strobe that is not equipped with a light control sensor for strobe photography, #7 to #
14, and the second light control sensor 3 provided in the camera 1 performs light control photography (#15).

According to this embodiment, in a camera having a second light control sensor 3 having a different light receiving angle from the first light control sensor 8, when the strobe 5 having the first light control sensor 8 is attached, When photographing with a strobe, the focus is placed on the output of the first light control sensor 8, so highly accurate light control can be expected, and a strobe without a light control sensor can be mounted. When taking photos with a flash, be careful not to use too much force.
Since light control is performed by the second light control sensor 3 placed on the camera side, strobe photography can be performed even with TTL light control strobes that do not have a light control sensor, which exist in large quantities on the market. becomes possible.

Note that in this embodiment, the first light control sensor 8 on the strobe side
Although the control is performed with emphasis on the output of the camera, it is of course possible to perform control with emphasis on the second light control sensor 3 on the camera side.

(Correspondence between the invention and the embodiments) In this embodiment, the first dimming sensor 8 is the first dimming sensor 8 of the present invention.
The second light control sensor 3 corresponds to the second light control sensor, and the portion of the control circuit 13 that performs the operations #7 to #15 in FIG. 4 corresponds to the light control means.

(Effects of the Invention) As explained above, according to the present invention, when a strobe having a light control sensor is attached, not only the first light control sensor output that can be expected to perform accurate light control but also The output of the light control sensor on the camera side is also taken into account when controlling the light intensity, and when a strobe without a light control sensor is attached, the light control is performed using the output of the light control sensor on the camera side. This allows for more accurate dimming control when a strobe with a dimming sensor is attached, and even when a strobe without a dimming sensor, which exists in large numbers on the market, is attached. It becomes possible to take pictures.

[Brief explanation of the drawing]

Fig. 1 is a front view showing a camera and a strobe according to an embodiment of the present invention, Fig. 2 is a block diagram showing the configuration of each, and Fig. 3 shows the light receiving range of the light control sensor on the camera side and the strobe side. FIG. 4 is a flowchart showing the operation in an embodiment of the present invention, and FIG. 5 is a diagram showing the correlation between a conventional strobe light control method and a strobe (TTL/external). 1... Camera, 3... Second light control sensor, 5... Strobe, 8... First light control sensor, 13... ...Control circuit.

Claims (1)

[Claims] (1) A strobe having a first light control sensor that has a different light receiving angle from a second light control sensor disposed on the camera side, and a second light control sensor arranged on the camera side.
In strobe photography when a strobe having the first light control sensor and the first light control sensor is attached, light control is performed based on the outputs of the first light control sensor and the second light control sensor. A camera/strobe equipped with an electronic camera having a dimming control means that performs dimming control based on the output of a second dimming sensor on the camera side when a strobe without a dimming sensor is attached. system.