JP2003116026A - Imaging device and method for displaying its exposure - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an imaging device for accurately obtaining an exposure information display with good handleability. SOLUTION: The imaging device comprises a beam attenuation rate control means having a combination of an aperture stop 11b and an ND filter 11c provided in an imaging optical system; an exposure control means (15, 40) for controlling the attenuation rate control means; and a display means 30 for displaying the equivalent diaphragm stop of a numeric value converted from the attenuation rate into attenuated light, by the aperture stop corresponding to the attenuation rate applied by the exposure control means and together the real diaphragm stop of the actual aperture diaphragm stop, when the attenuation rate is controlled by using the attenuation rate control means.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image pickup apparatus and a method of displaying its exposure.

[0002]

2. Description of the Related Art In an electronic image pickup device, the area of an image pickup element is smaller than that of a photographic film. Therefore, even if the aperture value is reduced, even if the aperture value is the same (F value), a camera using a film is compared. As a result, the aperture diameter becomes smaller, so that the influence of diffraction becomes more significant. Therefore, the ND filter (Neu
It has been known to avoid diffraction by using a true Density Filter) together with an aperture. Conventionally, especially in a moving image capturing device such as a video movie, a shutter speed can be freely set to secure a moving image quality (avoid jerkiness interference). It has been widely used due to the fact that it cannot be selected.

On the other hand, in the case of an electronic still camera (an electronic camera typified by a digital camera) mainly for still image shooting, a high-speed shutter may be used when shooting a high-luminance object, so that a conventional ND filter is used. Although the necessity was low, the need for using an ND filter together has been increasing because the size of the image sensor and the increase in the number of pixels have increased in recent years.

However, when an ND filter is also used for exposure control of an electronic camera, how to perform exposure display is a very important issue. In other words, when an ND filter and an aperture are used together in this way, a problem does not occur in a video movie or the like because a detailed exposure display is usually unnecessary, but as an electronic camera, the aperture value is usually a natural function. And detailed exposure display such as shutter speed (exposure time) is required. However, the N
No effective exposure display method has been found when using a D filter and an aperture together.

[0005]

SUMMARY OF THE INVENTION It is an object of the present invention to provide an image pickup apparatus capable of providing accurate and easy-to-use exposure information display.

[0006]

The present invention has taken the following means in order to solve the above problems. An image pickup apparatus according to the present invention is an aperture stop (aperture) provided in an image pickup optical system.
And a light transmittance control means (ND filter), which is configured as a combination with a light reduction ratio control means for controlling a light reduction ratio for an image in the imaging optical system, and a light reduction ratio control for controlling an exposure to a subject. An image pickup apparatus comprising an exposure control means for controlling the means, characterized in that the display means performs the following display. (1) Corresponding to the dimming rate applied by the exposure control means,
An equivalent aperture value, which is a numerical value obtained by converting the extinction ratio into extinction by an aperture stop, and an actual aperture value, which is an actual aperture stop value when the extinction ratio is controlled using the extinction ratio control means. Is also displayed. (2) Corresponding to the dimming rate applied by the exposure control means,
The actual aperture value, which is the actual aperture stop value when the dimming rate control means is controlled by the dimming rate control means, and the transmittance of the transmittance control means at that time are also displayed. (3) Corresponding to the dimming rate applied by the exposure control means,
The equivalent aperture value, which is a numerical value obtained by converting the extinction ratio into the extinction by the aperture stop, is displayed as the aperture stop value.

The present invention may also be an invention comprising a method for performing each of the above means. That is, in an exposure display method of an image pickup apparatus that includes an aperture stop and an ND filter and controls the aperture of the stop and the transmittance of the ND filter in order to control the exposure to a subject, the exposure display method of (1) is applied. The equivalent aperture value corresponding to the exposure and the actual aperture value used corresponding to the exposure are displayed together. (2) The actual aperture value and the transmittance used corresponding to the applied exposure shall be displayed together. (3) Display the equivalent aperture value corresponding to the applied exposure as the aperture aperture value. Is characterized by.

[0008]

DETAILED DESCRIPTION OF THE INVENTION An embodiment of the present invention will be described with reference to the drawings. FIG. 1 is a schematic block diagram of an electronic camera according to the present invention.

In FIG. 1, an optical image of a subject that has passed through a lens group 11 including an ND combined aperture 11a, which will be described in detail later, is converted into an electric signal by a CCD 12 and an analog image signal by an image pickup circuit 13. The analog image signal is converted into a digital image signal (hereinafter also referred to as “image information”) by the A / D converter 14, and is temporarily stored in the volatile built-in memory 25. The built-in memory 25 has a high speed, for example, SDRAM (Synchronous Dy).
natural Random Access Memor
y), which is also used as a work area for image processing described later.

The image processing circuit 21 performs processing such as conversion processing of color information of image information temporarily stored in the built-in memory 25 and conversion of the number of pixels. Then, the image information that has undergone various image processes in the image processing circuit 21 is, for example, JPEG compressed by the compression / expansion unit 22, and recorded in the removable memory 20 such as a smart medium.

When displaying a photographed image, the image information after the image processing is passed through the LCD driver 31.
It is displayed on the image display LCD 30.

When the image recorded in the removable memory 20 is displayed, the image information read from the removable memory 20 is expanded by the compression / expansion unit 22, and for example, predetermined image processing is performed by the image processing circuit 21. After that, the image is displayed on the image display LCD 30 as in the case of shooting.

The system controller 40 reads a basic control program of the electronic camera from a non-volatile memory 41 such as a flash memory and controls the entire electronic camera. The system controller 40 also receives an input from the operation unit 46 (including a release button, a cross key, and the like (not shown)) and performs control according to the input. The system controller 40 also controls the power supply unit (not shown) to manage the power supply of the entire electronic camera. Further, the syscon 40 drives and controls the lens group 11 via the lens driving circuit 15.

FIG. 2 shows an example of the structure of the ND combined diaphragm 11a. As shown in FIG. 2A, the diaphragm unit 11b,
The ND filter 11c is arranged such that each light transmitting surface is perpendicular to the optical axis. Aperture unit 11b
Are always arranged on the optical path of the optical system. The diaphragm unit 11b is a well-known iris diaphragm composed of a plurality of thin plates (diaphragm blades) whose central portion has a polygonal shape (or a substantially circular shape), and has an aperture diameter (that is,
Aperture value) is designed to change. ND filter 1
As shown in FIG. 2B, 1c is movable about a fulcrum O (in the direction of the arrow in the figure), and when used,
It is arranged on the optical path, is removed from the optical path when not in use, and is controlled to be located in the vicinity thereof.

In the above arrangement, when the aperture value (hereinafter also referred to as "F value") is small, the aperture diameter of the aperture unit 11b is large, so that the diffraction of the optical image by the aperture unit 11b does not occur. Therefore, since the exposure adjustment only needs to be performed by the aperture unit 11b, the ND filter 1
1c is not used (off state). However, when the aperture value becomes smaller, the influence of diffraction due to the opening of the aperture unit 11b cannot be ignored, so the ND filter 11c is inserted in the optical path (ND filter 11c is turned on), and the aperture unit 11b and the ND filter 11c Used together. In addition,
As the ND filter 11c, a filter that diminishes the amount of transmitted light by two steps (2 EV) (that is, a filter that has a transmittance τ = 0.25) is used. FIG. 3 shows how the aperture value of the aperture unit 11b changes according to exposure and how the ND filter 11c is turned on / off. The vertical axis of FIG. 3A indicates the F value by controlling the aperture, and the horizontal axis indicates the aperture and ND.
The imaginary F value (referred to as an “equivalent F value”) when the extinction rate obtained as a result of the combination of the filters is converted into the extinction by the diaphragm (only) is shown. Note that FIG. 3 (b)
FIG. 6 is a diagram showing an ON / OFF control condition of the ND filter 11c.

In FIG. 3, the F value from 2 to 8 is ND.
Although the filter 11c is not used, the aperture diameter of the diaphragm becomes small when the F value is larger than 8, so the ND filter 11c is turned on in order to avoid the influence of diffraction by the diaphragm unit 11b. In addition, in FIG.
In order to avoid an abnormal operation such as hunting, the ND filter 11 is closed when the F value exceeds 8 when the diaphragm is closed.
When c is inserted and the diaphragm is opened, hysteresis control is employed to remove (turn off) the ND filter 11c from the optical path when the F value becomes smaller than 8.

In the above structure, if only the F value and the shutter speed by the aperture of the camera are displayed, as in the case of the conventional camera without the ND filter,
When the ND filter 11c is used together with the aperture unit 11b, it is impossible to sufficiently display information necessary for exposure. Further, it is not known whether the ND filter 11c is used. Therefore, in the embodiment of the present invention, for example,
Items such as those shown in the following Table 1 are displayed on an image display LCD, for example.
Displayed on a part of 30. (Note that, in the present invention, the shutter speed display is assumed to be performed in the same manner as in the conventional case, and in the following, only the display related to the aperture and ND will be described.)

[Table 1]

In each display example of Table 1, in display example 1,
When the ND filter 11c is not used, only the F value (actual diaphragm value) by the diaphragm unit is displayed, and when the ND filter 11c is inserted, the equivalent F value and the actual diaphragm value are displayed together. ing. The actual aperture value is shown in parentheses.

In the second display example, the diaphragm unit 11b.
The actual aperture value by and the degree of dimming by the ND filter 11c (that is, the transmittance) are also displayed. In this display example, ND0 indicates that dimming by the ND filter 11c is 0, that is, the ND filter 11c is not inserted, and ND2 has dimming increased by two stages (2EV) by the ND filter 11c. That is, ND
This shows that the filter 11c is inserted. At this time, in order to display the transmittance (degree of dimming) of the ND filter, a numerical value of the transmittance (25% in this example) or a "density value" which is a logarithm thereof is displayed, or a reciprocal of the transmittance (exposure). It is also called a multiple: it goes without saying that 4) may be indicated in this example.

According to the display examples 1 and 2, the user can know the information regarding the exposure amount accurately, and since the actual aperture value information is displayed, the user can accurately obtain the information including the depth of field information. Exposure control information can be obtained.

Further, like the display example 3, only the equivalent F value may be shown regardless of whether the ND filter 11c is inserted. In the case of the display example 3, whether or not the ND filter 11c is used cannot be accurately grasped, but since the equivalent F value is displayed, the accurate F value can be grasped at least for the exposure amount information, and the display parameter Since the number of is not increased compared to the conventional one, the user can easily understand and the usability of the camera is improved.

Each parameter displayed in the above embodiment may be based on the control state of the diaphragm or ND filter that is actually controlled at that time depending on the specifications of the camera, or may be used before actual control. Of course may be based on an assumed control state.

The present invention is not limited to the above embodiments of the invention. In the above embodiment, only three display examples are shown, but any display method may be used as long as the display allows the accurate F value to be understood. Further, although the display portion is not particularly described in the above-mentioned embodiment, it is not particularly limited and may be a place which can be visually recognized by the user. Further, in the above embodiment, an example in which the number of ND filters is one is shown, but the present invention is not limited to this, and a plurality of ND filters may be prepared. Also, ND
The light transmittance of the filter is not limited to that in the above embodiment, and any light transmittance can be used. Of course, various modifications can be made without departing from the scope of the present invention.

[0024]

According to the present invention, when the ND filter and the diaphragm are used together, the information on the exposure amount can be accurately known, and by displaying the actual diaphragm value information, the depth of field information can also be obtained. It is possible to obtain accurate exposure adjustment information including the information. Further, by displaying only the equivalent F value, the information can be easily grasped and the usability of the camera is improved.

[Brief description of drawings]

FIG. 1 is a schematic block diagram of an electronic camera according to the present invention.

FIG. 2 is a diagram showing a configuration example of an ND combined diaphragm.

FIG. 3 is a diagram showing a change in aperture value of an aperture unit according to exposure and a state of on / off control of an ND filter.

[Explanation of symbols]

11 ... Lens group 11a ... ND combination diaphragm 11b ... Aperture unit 11c ... ND filter 12 ... CCD 13 ... Imaging circuit 14 ... A / D converter 15 ... Lens driving circuit 20 ... removable memory 21 ... Image processing circuit 22 ... Compression / expansion section 25 ... Built-in memory 30 ... LCD for image display 31 ... LCD driver 40 ... Syscon 41 ... Nonvolatile memory 46 ... Operation unit

─────────────────────────────────────────────────── ─── Continuation of front page (51) Int.Cl. ⁷ Identification code FI theme code (reference) H04N 5/238 H04N 5/238 Z F term (reference) 2H002 CC00 CC21 CC23 FB53 JA07 2H083 AA05 AA26 AA29 AA32 AA35 AA53 2H102 AA03 5C022 AA00 AB01 AB12 AB14 AC11 AC55 AC69 CA00

Claims (6)

[Claims] 1. An extinction ratio control unit configured to combine an aperture stop and a transmissivity control unit provided in an imaging optical system to control an extinction ratio of an image in the imaging optical system, and an exposure to an object. In order to control, the exposure control unit that controls the extinction ratio control unit and the extinction ratio applied by the exposure control unit are numerical values obtained by converting the extinction ratio into extinction by the aperture stop. Display means for displaying the equivalent aperture value and the actual aperture value which is the actual aperture aperture value when the extinction ratio is controlled using the extinction ratio control means. Image pickup device. 2. An extinction ratio control means for controlling an extinction ratio for an image in the imaging optical system, which is configured as a combination of an aperture stop and a transmittance control means provided in the imaging optical system, and an exposure for a subject. In order to control, the exposure control means for controlling the extinction rate control means, and the extinction rate is controlled by using the extinction rate control means corresponding to the extinction rate applied by the exposure control means. An image pickup apparatus comprising: an actual aperture value that is an actual aperture aperture value at that time; and a display unit that also displays the transmittance of the transmittance control unit at that time. 3. An extinction ratio control unit configured to combine an aperture stop and a transmissivity control unit provided in an image pickup optical system to control an extinction ratio of an image in the image pickup optical system, and an exposure to an object. In order to control, the exposure control unit that controls the extinction ratio control unit and the extinction ratio applied by the exposure control unit are numerical values obtained by converting the extinction ratio into extinction by the aperture stop. An image pickup apparatus comprising: a display unit that displays an equivalent aperture value as an aperture value. 4. A method of displaying exposure of an image pickup device, comprising an aperture stop and an ND filter, wherein the exposure of an object is controlled by controlling the aperture of the stop and the transmittance of the ND filter to perform exposure. The equivalent aperture value corresponding to the exposure and the actual aperture value used corresponding to the exposure are displayed together. 5. An exposure display method of an image pickup apparatus, comprising an aperture stop and an ND filter, wherein the exposure of an object is controlled by controlling the aperture of said stop and the transmittance of said ND filter to perform exposure. An image pickup apparatus, which displays the actual aperture value and the transmittance, which are used in correspondence with the selected exposure. 6. A method of displaying exposure of an image pickup apparatus, comprising: an aperture stop and an ND filter, and controlling the aperture of the stop and the transmittance of the ND filter to control exposure to a subject. An image pickup apparatus, which displays an equivalent aperture value corresponding to a given exposure as an aperture aperture value.