JP2012108243A - Image pickup apparatus and method for controlling image pickup apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To easily confirm a focus under a bright focus range when performing a manual focus by automatically setting a non-focus range into a blurred image and facilitating an acquisition of a focal peak.SOLUTION: The image pickup apparatus includes: manual focus determination means 38 for determining that a manual focus is performed; a reticle 4 capable of changing a diffusivity; diffusivity control means 32 for changing the diffusivity of the reticle; focal point detecting means 16 for detecting the focus state of the whole imaging surface of image pickup means 3; and spectroscopic means for diffracting light from a lens unit into the reticle and the focal point detecting means. When the manual focus determination means determines that the manual focus is performed, the focal point detecting means detects the focus state, and the diffusivity control means sets higher the diffusivity of a part of the reticle that corresponds to the non-focus range than the diffusivity of a part of the reticle that corresponds to the focus range, according to the focus state from the focal point detecting means.

Description

  The present invention relates to an imaging apparatus having a focusing screen whose diffusivity can be changed and a method for controlling the imaging apparatus.

  Conventionally, an optical viewfinder of a single-lens reflex camera used as an image pickup apparatus is required to have a brightness of a viewfinder image and easy to grasp a focus mountain. Here, the ease of grasping the focus mountain means that the greater the blurring of the unfocused portion such as the background, the clearer the difference from the focused portion and the easier it is to confirm the focus. For this reason, the aperture of the taking lens is generally opened during viewfinder observation, and the viewfinder image is brightened by passing a large amount of light. In addition, by passing light with an angle, the depth of field, which is the focus range, is narrowed, the out-of-focus part such as the background is easily blurred, and the focus mountain is easily grasped.

  By the way, the viewfinder image of a single-lens reflex camera reflects light from the photographic lens by a main mirror, forms an image on a focusing screen, and the photographer observes the finder image through a pentaprism and an eyepiece. The focusing screen has irregularities and diffuses light to change the direction of the light beam at an angle and reach the photographer's pupil so that a blurred image can be seen. The diffusion characteristics of the focusing screen are expressed as a diffusivity (transmittance) as a ratio of transmitted light and diffusing light. As the diffusivity of the focusing screen is higher, the blurred image becomes more prominent, and the viewfinder image is easy to grasp the focus mountain. On the other hand, the higher the diffusivity, the darker the viewfinder image. Conversely, the lower the diffusivity, the brighter the viewfinder image is, but the blurred image is not visible, and the viewfinder image is difficult to grasp. A single focusing screen balances the brightness of the viewfinder image with the ease of grasping the focus mountain. It was difficult to do.

  With single-lens reflex cameras, there are many users who fine-tune the focus with manual focus (MF) after focusing with autofocus (AF), and many users use a manual focus dedicated shooting lens, and the viewfinder image is dark, making it easy to grasp the focus mountain. The viewfinder has a problem that it is difficult to focus manually.

  Therefore, for example, Japanese Patent Laid-Open No. 6-258893 (Patent Document 1) has a brightness priority mode in which the brightness of the finder is prioritized, and the depth of field in the finder is the largest by a focusing screen that can change the diffusivity using liquid crystal. A technique is disclosed in which a photographer arbitrarily switches a shallow focus priority mode or a depth priority mode in which priority is given to expression of depth of field at the time of shooting.

JP-A-6-258893

  However, in the prior art disclosed in Patent Document 1 described above, when switching to the focus priority mode or the depth priority mode that prioritizes the expression of the depth of field at the time of shooting, the entire finder image becomes dark and the subject is difficult to see. . For this reason, there is a problem that it is difficult to focus on the MF because the subject image that is the in-focus portion is difficult to look dark even if the blur of the out-of-focus portion such as the background is increased. In addition, in the prior art, each mode must be switched by the user with the operation member. For example, when the focus is finely adjusted with MF after AF in the brightness priority mode, the operation member changes to the focus priority mode. And you may miss a photo opportunity.

(Object of invention)
An object of the present invention is to make it possible to automatically see a blurred image so that a focus mountain can easily grasp the out-of-focus range when performing manual focus, and to make it easy to confirm the focus range brightly. An imaging device and a method for controlling the imaging device are provided.

  In order to achieve the above object, an imaging apparatus according to the present invention includes manual focus determination means for determining that manual focus is performed by a manual focus operation member provided in the lens unit, and light from the lens unit. An imaging means for receiving light, a focusing plate whose diffusivity can be changed, a diffusivity control means for changing the diffusivity of the focusing screen, and a focus detection means for detecting the focus state of the entire imaging surface by a signal from the imaging means And a spectroscopic unit that splits the light from the lens unit into the focusing screen and the focus detection unit, and when the focus detection unit determines that manual focus is performed by the manual focus determination unit, the focus state The diffusivity control means detects the out-of-focus range according to the focus state from the focus detection means. Was spreading factor of the portion of the focusing screen, it is characterized in that higher than the diffusion rate of the portion of the focusing screen which corresponds to the focusing range.

  According to the present invention, when manual focusing is performed, a blurred image can be automatically seen so that the out-of-focus area can be easily grasped by the focus mountain, and the in-focus area can be brightened and easily confirmed. .

1 is a block diagram illustrating a configuration of a camera as an imaging apparatus that is an embodiment of the present invention. It is a figure which shows the external appearance of the camera of an Example. It is a flowchart which shows operation | movement of the camera of an Example. It is the schematic which showed an example which changes the diffusivity of a focusing screen partially.

  The mode for carrying out the present invention is as described in the following examples.

  First, with reference to FIGS. 1 and 2, the main configuration of a camera as an imaging apparatus according to an embodiment of the present invention will be described. FIG. 1 is a block diagram showing the internal configuration of the camera 1. 2A and 2B are external views of the camera 1. FIG. 2A is a front perspective view, and FIG. 2B is a rear perspective view. A lens unit 2 is provided in front of the camera 1, and light incident from the lens unit 2 is configured to form an image on an imaging unit 3 in the camera 1 capable of focus detection and exposure detection. The imaging means 3 receives light from the lens unit 2 and can be photographed with an electronic shutter. Between the lens unit 2 and the imaging means 3, a spectroscopic means 5 which is a half mirror for reflecting light to the focusing screen 4 is arranged. The light reflected by the spectroscopic means 5 is focused on the focusing screen 4 and guided to the photographer's pupil through the pentaprism 6 and the finder 7. The focusing screen 4 can change the diffusivity. The light transmitted by the spectroscopic means 5 enters the image pickup means 3. When the photographer presses the release button 8 halfway (SW1), photometry and focus detection are started by the image pickup means 3, and the focus lens 10 is driven by the lens drive means 9 in the lens unit 2. Next, when the photographer fully presses the release button 8 (SW2), the image pickup means 3 runs the electronic shutter to perform photographing. Then, the imaging means 3 performs an exposure operation for starting charge accumulation and charge readout operations. Then, the captured image is recorded and stored in a recording medium 14 provided on the side surface of the camera 1 and attached to the image recording / reading means 11. The image stored in the recording medium 14 is displayed on the display device 27 when the image playback button 13 on the back of the camera 1 is pressed.

  Next, the camera 1 of the present embodiment includes a system control circuit 15 that controls the entire camera 1. The system control circuit 15 is composed of a CPU, an MPU, and the like, and controls the operation of each circuit described later. The system control circuit 15 includes a focus detection unit 16. When focus detection is started, the system control circuit 15 controls the lens driving unit 9 based on a signal from the imaging unit 3 and drives the focus lens 10 in the optical axis direction. To focus. In addition to the imaging pixel group, the imaging unit 3 includes a focus detection pixel group and a pupil division lens group disposed in front of the focus detection pixel group. The focus detection method includes imaging surface phase difference AF that performs focus detection based on a phase difference on the imaging surface, contrast AF that performs focus detection based on the contrast ratio of the captured image, or contrast by driving the imaging unit 3 back and forth in the optical axis direction. For example, a wobbling method for performing AF. The focus detection unit 16 can detect the focus state of the entire imaging surface. Since these are well-known, detailed description is abbreviate | omitted.

  Further, the system control circuit 15 includes an exposure detection means 17. When the photometry is started, the exposure detection unit 17 determines the aperture value of the aperture 18 in the lens unit 2 and the electronic unit of the imaging unit 3 in accordance with the imaging conditions set in advance by the photographer based on the signal from the imaging unit 3. Determine shutter speed and charge accumulation time. When the photographing operation is started by the release button 8 (SW2), the system control circuit 15 controls the exposure control unit 19 to drive the diaphragm 18 and the electronic shutter to the determined values. The system control circuit 15 causes the exposure control unit 19 to output a pulse signal necessary for driving the imaging unit 3 from the timing generator 20. The imaging means 3 performs charge accumulation and charge read operations according to the pulse signal output from the timing generator 20.

  The charges read from the image pickup means 3 are digitized by the A / D conversion circuit 21 and sent to the image processing circuit 22. The sent image is subjected to white balance adjustment, image compression processing, and the like by the image processing unit 23 in the image processing circuit 22, and is recorded and stored in the recording medium 14 through the image recording / reading unit 11 by the recording control unit 24. The recording medium 14 is a general SD card or CF card. The captured image stored in the recording medium 14 is read into the display control unit 25 in the image processing circuit 22 by the image recording / reading means 11 when the image reproduction button 13 is pressed, converted into an analog form by the D / A conversion circuit 26, and displayed. Displayed on the device 27. The display device 27 may be a general liquid crystal or organic EL.

  In the present embodiment, the lens unit 2 is described only with the focus lens 10, but it may be a lens having a zoom lens or the like, or may be of an integral type or a separate type that can be replaced. In addition to the fixed spectroscopic means 5, a main mirror and a sub mirror are rotatably arranged, and the focus by the phase difference AF is provided separately from the focus detection means 16 that performs focus detection based on a signal from the imaging means 3. Detection means may be provided. Since these configurations described above are publicly known, detailed description thereof will be omitted.

  Next, a method for setting shooting conditions will be described. The shooting mode setting means 28 which is a dial operation member can set the shooting mode. For example, automatic exposure mode, aperture priority exposure mode (Av), shutter speed priority exposure mode (Tv), manual mode (M), and valve mode (B) can be set. When the automatic exposure mode is set, the photographer arbitrarily sets an appropriate exposure value by the exposure setting means 29 which is a dial operation member, and the aperture value and the shutter speed are automatically determined so that the appropriate exposure is obtained at the time of shooting. The When the aperture priority exposure mode (Av), shutter speed priority exposure mode (Tv), and manual mode (M) are set, the aperture value setting means 30 and the shutter speed setting means 31 arbitrarily set the aperture value and the shutter speed. it can. When the bulb mode is set, shooting is started when the release button 8 (SW22) is pressed, exposure is continued while the release button 8 (SW2) is pressed, and exposure is ended when the release button 8 (SW2) is released, Shutter speed can be determined during shooting.

  Next, a method for changing the diffusivity of the focusing screen 4 will be described. In addition to the above-described configuration, the camera 1 has a diffusivity control unit 32 that changes the diffusivity of the focusing screen 4 entirely and partially, and a focus frame display unit that displays a focus range on the focusing screen 4 (also referred to as a focus area). 33. A focus range selection means 34 for moving the position of the focus frame is included. The focusing screen 4 is a dot-matrix liquid crystal in which pixel-like liquid crystal groups are arranged in a grid pattern. A charge is applied from the diffusivity controller 32 controlled by the system control circuit 15, and the molecules in each grid-aligned liquid crystal are displayed. The diffusion rate can be partially changed by changing the arrangement direction. For example, the diffusivity of the focusing screen 4 can be lowered by arranging the alignment direction of the liquid crystal molecules horizontally with respect to the optical axis direction of the light reflected from the spectroscopic means 5. The diffusivity of the focusing screen 4 can be partially increased by changing the charge applied from the diffusivity control section 32 only in a predetermined range of the focusing screen 4 and tilting the alignment direction of the liquid crystal molecules from the horizontal.

  The focus frame display means 33 displays the focus range arbitrarily selected by the photographer by the focus range selection means 34 on the focusing screen 4 under the control of the system control circuit 15. As a method for displaying the focus frame, there are a method of projecting LED illumination onto the focusing screen 4 and a method of separately stacking a focus frame display liquid crystal on the focusing screen 4. Space is required. For this reason, the focus range of the focusing screen 4 which is a dot matrix liquid crystal is displayed by the focus frame display means 33 so as to increase the diffusivity in a frame shape to a light shielding state.

  Next, the method of changing the diffusivity of the focusing screen 4 during MF, which is a feature of the present embodiment, is a schematic diagram showing an example of partially changing the diffusivity of the focusing screen 4 during MF in FIG. This will be described with reference to the drawings. In addition to the above-described configuration, the lens unit 2 includes a focus ring 35 that is a manual focus operation member for the photographer to manually adjust the focus, a lens position detection unit 36 that detects the position of the focus lens 10, and a focus mode. Focus mode switching means 37 that can switch between the AF mode and the MF mode is provided. The focus ring 35 is interlocked so that the focus lens 10 can be moved in the optical axis direction. When the focus mode is switched to the MF mode, the photographer rotates the focus ring 35 to perform MF. When the mode is switched to the AF mode, the lens driving unit 9 is interlocked with the focus lens 10 and the photographer performs an AF operation by pressing the release button 8 halfway (SW11). The lens driving means 9 includes an ultrasonic motor, and is configured to enable MF when the photographer rotates the focus ring 35 even in the AF mode. The system control circuit 15 includes an MF determination unit 38. When the photographer rotates the focus ring 35 and the focus lens 10 is driven, the photographer performs MF from the output of the lens position detection unit 36. Determine and automatically switch from AF mode to MF mode. Since the MF in the AF mode by the ultrasonic motor is known, detailed description thereof is omitted. The lens position detection unit 36 is a rotary encoder, an optical sensor, or the like, and detects the position of the focus lens 10 or the position of the focus ring 35 linked to the focus lens 10. The lens driving means 9 may be a servo motor or the like, or may have a lens structure dedicated to MF without the lens driving means 9.

  Next, there is a method for changing the diffusivity of the focusing screen 4 during MF. When the photographer turns on the power of the camera 1, the diffusivity of the entire surface of the focusing screen 4 is set to a predetermined value in STEP 1 of FIG. The diffusion rate D = X1. The diffusivity D = X1 is a value that gives priority to the brightness of the finder image and has a low diffusivity, and is set in the camera 1 in advance. When the photographer observes the finder 7, for example, as shown in FIG. 4A, a finder image with a bright subject and the entire background can be seen, so that the composition can be easily confirmed. Separately, a changing means may be provided so that the photographer can arbitrarily change the diffusion rate D = X1. In addition, the aperture 18 of the lens unit 2 is in an open state with priority given to the brightness of the finder image and the ease of grasping the focus mountain. The focus mode may be either auto focus mode (AF mode) or manual focus mode (MF mode).

  Next, in STEP 2, the system control circuit 15 detects the presence / absence of the lens position detection means 36. The system control circuit 15 reads information from the lens position detection means 36, and if the information can be read, it is determined that an AF-capable lens unit provided with the lens position detection means 36 is attached to the camera 1.

  If the information cannot be read from the lens position detecting means 36, it is determined that the MF dedicated lens unit not provided with the lens position detecting means 36 is attached to the camera 1. First, when it is determined that an AF-capable lens unit provided with the lens position detection means 36 is attached to the camera 1, manual focus determination (MF determination) is performed in STEP3. When the photographer rotates the focus ring 35, the linked focus lens 10 is driven. When the position information is output from the lens position detection unit 36 to the system control circuit 15, the system control circuit 15 determines that the photographer is performing MF by the MF determination unit 38. When the focus mode is the AF mode, when the focus mode switching unit 37 automatically switches to the MF mode, the MF determination unit 38 detects that the mode has been switched to the MF mode, and the photographer performs MF. You may make it the structure determined to be.

  Next, in STEP 4, the imaging unit 3 performs focus detection on the entire imaging surface, and determines the in-focus range and the out-of-focus range. For example, when focus detection is performed using the imaging surface phase difference AF described above, the in-focus range and the out-of-focus range are determined based on a phase difference threshold set in advance in the camera 1. In STEP5, the diffusivity of the portion corresponding to the out-of-focus range of the focusing screen 4 is changed to diffusivity D = X2 based on the focus information (focus state information) detected in focus. The diffusivity D = X2 has a high diffusivity so that the blur image can be seen well, giving priority to the ease of grasping the focus point of the finder image, and is set in the camera 1 in advance. The diffusivity of the portion corresponding to the focusing range of the focusing screen 4 maintains the diffusivity D = X1. At this time, the relationship of the diffusivity is X1 <X2. Separately, a changing means may be provided so that the photographer can arbitrarily change the diffusion rate D = X2. When the photographer observes the finder 7, for example, as shown in FIG. 4B, when the background is in the in-focus range, the background appears bright and unfocused, and the subject image in the out-of-focus range is darkly blurred. It appears as an image and it is clear that the subject is not in focus. When the photographer rotates the focus ring 35 and performs MF so as to focus on the subject image, the subject image gradually becomes brighter and blurred as shown in FIG. 4C, and the background becomes darker and blurred. Become a statue. When the subject image is brightest and looks clear, it is when the subject image is in focus, and the finder image is bright and easy to check the focus mountain even with MF. In STEP 6, the photographer fully presses the release button 8 (SW2) to perform photographing.

  If it is determined in STEP 2 that the MF dedicated lens unit not provided with the lens position detecting means 36 is attached to the camera 1, the focus detection of the entire imaging surface or a predetermined location by the imaging means 3 is started in STEP 4. When the photographer rotates the focus ring 35 to perform MF, and the phase difference of the entire imaging surface or a predetermined location output from the imaging means 3 changes uniformly, the MF determination means 38 indicates that the photographer is performing MF. judge. When it is determined that the MF is performed, the in-focus range and the out-of-focus range are discriminated, and the portion corresponding to the out-of-focus range of the focusing screen 4 based on the focus information (focus state information) detected by the focus. Is changed to a diffusion rate D = X2. In STEP 5, the photographer fully presses the release button 8 (SW2) to perform photographing.

  As described above, according to the present embodiment, when performing MF, the out-of-focus portion (out-of-focus range) is automatically converted into a finder image having a large blur so that the focus mountain can be easily grasped, and the in-focus portion ( It is possible to provide a camera that can switch to a finder image that is bright and easy to check in focus.

  As mentioned above, although the preferable Example of this invention was described, this invention is not limited to these Examples, A various deformation | transformation and change are possible within the range of the summary. For example, in STEP 1 of FIG. 3, the ease of composition confirmation is emphasized, and the diffusivity D = X1 of the focusing screen 4 is set low. However, if priority is given to focus confirmation, the diffusivity D = X1 is set high. May be. In this case, in STEP 5, the diffusivity of the portion of the focusing screen 4 corresponding to the in-focus range determined by the focus state information may be changed to diffusivity D = X2. At this time, the relationship between the diffusion rates is X1> X2.

2 lens unit 4 focusing screen 5 spectroscopic unit 15 system control circuit 16 focus detection unit 32 diffusivity control unit 35 focus ring 37 focus mode switching unit 38 MF determination unit

Claims (4)

Manual focus determination means for determining that manual focus is performed by a manual focus operation member provided in the lens unit;
Imaging means for receiving light from the lens unit;
A focusing screen with variable diffusivity;
Diffusivity control means for changing the diffusivity of the focusing screen;
A focus detection unit that detects a focus state of the entire imaging surface based on a signal from the imaging unit;
A spectroscopic unit that splits the light from the lens unit into the focus plate and the focus detection unit;
When the focus detection unit determines that manual focus is performed by the manual focus determination unit, the focus detection unit detects a focus state,
The diffusivity control means determines the diffusivity of the part of the focusing screen corresponding to the out-of-focus range according to the focus state from the focus detection means, and the diffusivity of the part of the focusing screen corresponding to the focus range. An imaging device characterized by being higher than that.   The imaging apparatus according to claim 1, wherein the manual focus determination unit determines that manual focus is performed by detecting a movement of the manual focus operation member. Focus mode switching means that can switch the focus mode to either auto focus mode or manual focus mode,
The imaging apparatus according to claim 1, wherein the manual focus determination unit determines that manual focus is performed when the focus mode switching unit switches to the manual focus mode. Manual focus determination means for determining that manual focus is performed by a manual focus operation member provided in the lens unit;
Imaging means for receiving light from the lens unit;
A focusing screen with variable diffusivity;
Diffusivity control means for changing the diffusivity of the focusing screen;
A focus detection unit that detects a focus state of the entire imaging surface based on a signal from the imaging unit;
An imaging apparatus control method comprising: a spectroscopic unit that splits light from the lens unit into the focusing plate and the focus detection unit;
When the focus detection unit determines that manual focus is performed by the manual focus determination unit, a step of detecting a focus state;
According to the focus state from the focus detection means, the diffusivity of the part of the focusing screen corresponding to the out-of-focus range is determined by the diffusivity control means, and the diffusivity of the part of the focusing screen corresponding to the focus range. And a step of making the height higher than that of the imaging device.

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