Optical instrument and method for controlling the same

Abstract

To obtain a plurality of pieces of moving image data to be composited with each other so as not to reduce the frame rate of the moving image data after the composition.SOLUTION: An optical instrument 100 has: a first optical system 120a and a second optical system 120b that are arranged in parallel; first optical members 103a, 105a that can be driven and are provided in the first optical system; second optical members 103b, 105b that are provided in the second optical system and are optical members having the same function as the first optical members; and control means 112 that controls the drive of the first and second optical members. The control means controls the drive of the first and second optical members so as to provide the difference in the position of drive between the optical members.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to an optical instrument having two optical systems arranged side by side. [Background technology]

[0002] High Dynamic Range (HDR) image data can be obtained by combining underexposed image data and overexposed image data. However, with the conventional method of obtaining underexposed image data and overexposed image data by capturing images consecutively, HDR still image data can be obtained, but it is difficult to obtain video data.

[0003] Patent Document 1 discloses a method for capturing video by changing the ISO sensitivity to capture frame image data with proper exposure, underexposure, and overexposure three times in succession, and then obtaining HDR video data that includes a frame image synthesized from these three frame image data. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Patent No. 5574792 Summary of the Invention [Problem to be solved by the invention]

[0005] However, in the method disclosed in Patent Document 1, three frame image data sets with different exposures are obtained by capturing images multiple times, so the frame rate of the synthesized HDR video data is lower than the frame rate of video data obtained by normal capturing.

[0006] The present invention provides an optical device capable of obtaining a plurality of moving image data to be combined together without lowering the frame rate of the combined moving image data. [Means for solving the problem]

[0007] An optical device according to one aspect of the present invention includes a first optical system and a second optical system arranged in parallel, a driveable first optical member provided in the first optical system, a second optical member provided in the second optical system and having the same function as the first optical member, and a control means for controlling the drive of the first and second optical members, wherein the control means controls the drive of the first and second optical members so as to provide a difference between the drive positions of the first and second optical members.

[0008] Another aspect of the present invention relates to a control method applied to an optical device having a first optical system and a second optical system arranged in parallel, a driveable first optical element provided in the first optical system, and a second optical element provided in the second optical system, the first optical element being the same optical element as the first optical element. The control method includes a step of controlling the drive of the first and second optical elements, and is characterized by controlling the drive of these optical elements so as to provide a difference between the drive positions of the first and second optical elements. Note that a program for causing a computer to execute processing in accordance with the control method also constitutes another aspect of the present invention. [Effects of the Invention]

[0009] According to the present invention, a plurality of moving image data to be combined with each other can be obtained without lowering the frame rate of the combined moving image data. [Brief explanation of the drawings]

[0010] [Figure 1] FIG. 1 is a block diagram showing the configuration of a camera system including an interchangeable lens according to a first embodiment. [Figure 2] 3 is a flowchart showing a process in the first embodiment. [Figure 3] 10A to 10C are diagrams for explaining aperture value setting and focus operation in the second embodiment. [Figure 4] 11 is a flowchart showing a focus process in the third embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0011] Hereinafter, an embodiment of the present invention will be described with reference to the drawings. [Example]

[0012] FIG. 1 shows a camera system (imaging system) 10 comprising a lens device (hereinafter referred to as an interchangeable lens) 100 as an optical device which is an embodiment of the present invention, and an imaging device (hereinafter referred to as a camera body) 200 to which the interchangeable lens 100 is detachably and communicably attached.

[0013] Interchangeable lens 100 is a twin-lens type interchangeable lens having a first optical system 120a and a second optical system 120b arranged in parallel. First optical system 120a includes, arranged in order from the object side to the image side, a fixed front lens group 101a, a variable magnification lens group 102a, an aperture 103a, a correction lens group 104a, and a focus lens group 105a. Note that although each lens group is shown as a single lens in the figure, in reality it is made up of one or more lenses.

[0014] The variable magnification lens group 102a moves in the optical axis direction by rotating a zoom ring (not shown) provided on the interchangeable lens 100. This changes the spacing between adjacent lens groups in the first optical system 120a, thereby varying the magnification from the wide-angle end to the telephoto end. The variable magnification lens group 102a may be driven in the optical axis direction by a zoom actuator such as a stepping motor or a DC motor.

[0015] The diaphragm 103a is driven by an diaphragm actuator 106a, which is configured using a stepping motor, a DC motor, or the like, to change its aperture diameter (aperture value). An diaphragm drive circuit 107a supplies a drive signal to the diaphragm actuator 106a to drive it. The light amount adjustment unit 116a is configured by the diaphragm 103a, the diaphragm actuator 106a, and the diaphragm drive circuit 107a.

[0016] The correction lens group 104a is driven in a shift direction perpendicular to the optical axis by an anti-shake actuator 108a, such as a stepping motor or a voice coil motor, to reduce (correct) image blur caused by camera shake such as hand shake. An anti-shake drive circuit 109a supplies a drive signal to the anti-shake actuator 108a. An anti-shake unit 117a is composed of the correction lens group 104a, the anti-shake actuator 108a, and the anti-shake drive circuit 109a.

[0017] The focus lens group 105a is driven by a focus actuator 110a, which is composed of a stepping motor, a voice coil motor, a vibration motor, etc., to move in the optical axis direction and perform focusing to bring the focal state closer to the in-focus state. A focus drive circuit 111a supplies a drive signal to the focus actuator 110a. The focusing unit 118a is composed of the focus lens group 105a, the focus actuator 110a, and the focus drive circuit 111a. The components of the second optical system 120b are designated by symbols obtained by replacing the symbols "a" with "b" used for the components of the first optical system 120a. The diaphragm 103a and the focus lens 105a arranged in the first optical system 120a correspond to a drivable first optical element. The diaphragm 103b and the focus lens group 105b arranged in the second optical system 120b, which have the same functions as the diaphragm 103a and the focus lens group 105a, respectively, correspond to a second optical element.

[0018] When the interchangeable lens 100 is attached to the camera body 200, power supply contacts and communication contacts 113a, 113b, and 113c (not shown) provided on the interchangeable lens 100 are connected to power supply contacts and communication contacts 207a, 207b, and 207c (not shown) provided on the camera body 200, respectively. By connecting the power supply contacts, power is supplied to the interchangeable lens 100 from a secondary battery (not shown), such as a lithium-ion battery, mounted in the camera body 200. By connecting the communication contacts, various types of information can be communicated between a lens control CPU (control means) 112 provided in the interchangeable lens 100 and a camera control CPU 206 provided in the camera body 200. While FIG. 1 shows a case where three-wire serial communication is performed, communication may be performed using other communication methods.

[0019] The camera body 200 is provided with an image sensor 201 configured with a photoelectric conversion element such as a CCD sensor or a CMOS sensor. The image sensor 201 photoelectrically converts (captures) an optical image (subject image) formed on its imaging surface by the first optical system 120a and the second optical system 120b. Specifically, light passing through the first optical system 120a forms an optical image in a region on the right side of the image sensor 201, and light passing through the second optical system 120b forms an optical image in a region on the left side of the image sensor 201. This allows the image sensor 201 to capture two optical images without mutual interference between the lights passing through the first optical system 120a and the second optical system 120b. The electric charges accumulated in the image sensor 201 are read out as analog image signals at predetermined timing and input to the video signal processing circuit 202.

[0020] A video signal processing circuit 202 serving as image processing means converts the analog image signal read from the image sensor 201 into a digital image signal, and performs various signal processing such as amplification and gamma correction on the digital image signal to generate a digital image signal (moving image data). The digital image signal is output to a camera control CPU 206, a display device 205 constituted by a liquid crystal display panel or the like, and a storage device 204 constituted by an optical disk, semiconductor memory or the like.

[0021] The video signal processing circuit 202 includes an AF signal processing circuit 203. The AF signal processing circuit 203 extracts high-frequency components and luminance components obtained from a group of pixels in an AF area, which is a focus detection region, from the digital imaging signal (or digital video signal), and generates a focus evaluation value signal as focus information. The focus evaluation value signal indicates the contrast state (imaging contrast), or in other words, sharpness, of the image, and changes as the focus lens groups 105a and 105b move. The focus position at which the value of the focus evaluation value signal, or in other words, the focus evaluation value, reaches its maximum (peak), is the in-focus position for that AF area.

[0022] The video signal processing circuit 202 also includes an image synthesis processing circuit 209. The image synthesis processing circuit 209 performs specific processing on the digital video signal obtained from the output of the image sensor 201 to convert the signal into a video compatible with the VR180 video format, which has a 180° angle of view. The optical axes of the first optical system 120a and the second optical system 120b are spaced apart from each other by the base length in a direction perpendicular to the optical axes, and the video signals obtained through the first optical system 120a and the second optical system 120b have parallax. This parallax can be used to generate VR180 video that allows stereoscopic viewing. By viewing the VR180 video through a viewing device such as a head-mounted display, the user can see a stereoscopic image.

[0023] The image synthesis processing circuit 209 can also convert multiple video signals obtained through the first optical system 120a and the second optical system 120b into VR180 format video signals separately and synthesize these video signals to obtain VR180 video as a single video signal without parallax. For example, it can generate overexposed and underexposed video signals through the first optical system 120a and the second optical system 120b, respectively, and synthesize these video signals to generate HDR video data. Note that the image synthesis processing circuit 209 does not necessarily have to be built into the camera body 200, but may also be located outside the camera body 200.

[0024] The lens control CPU 112 includes an internal storage device (storage means) 114. The internal storage device 114 stores table data indicating the focus movement amount relative to the aperture stop amount from the fully open position when the aperture actuators 106a and 106b are driven.

[0025] The camera control CPU 206 includes an ISO sensitivity adjustment unit 210. The ISO sensitivity adjustment unit 210 is implemented in the camera control CPU 206 and determines the ISO sensitivity. The ISO sensitivity adjustment unit 210 determines the ISO sensitivity based on the output value of a photometry unit (AE) (not shown) that measures the amount of light received from a subject.

[0026] The operation unit 208 is composed of operation members such as multiple buttons and dials. By pressing buttons or rotating dials, the ISO sensitivity, shutter speed, and aperture value, which determine the exposure conditions during image capture, can be set. In addition, the camera body 200 is provided with operation members for setting the image capture mode, issuing image capture instructions, setting the HDR effect level, etc.

[0027] 2 shows the processing (control method) executed by the lens control CPU 112 when capturing video. The lens control CPU 112 executes this processing in accordance with a computer program. Note that, although this embodiment describes a case in which the lens control CPU 112 of the interchangeable lens 100 executes the processing, the same processing may also be executed by a CPU of a lens-integrated imaging device (optical equipment). In other words, the embodiments of the present invention include not only lens devices but also lens-integrated imaging devices.

[0028] In step S101, the lens control CPU 112 communicates with the camera control CPU 206 and receives first and second drive amounts for the apertures (first and second apertures) 103a and 103b. The drive amount of the aperture here refers to the drive amount from the open position as the aperture's reference position, and can be rephrased as the aperture value as a drive position. The first and second drive amounts may be directly input by the user to the camera body 200, or may be determined by the camera control CPU 206 based on the HDR effect amount specified by the user. In this way, the lens control CPU 112 accepts input of information regarding the first and second drive amounts (drive positions that are different from each other). The information regarding the first and second drive amounts may be the first and second drive amounts themselves, or may be information that can be converted into the first and second drive amounts.

[0029] In the next step S102, it is determined whether the first and second drive amounts are allocated to aperture 103a or aperture 103b. Regarding the second drive amount, the second drive amount itself may be received, or the difference from the first drive amount may be received. In this example, the lens control CPU 112 receives the first drive amount and also receives the difference from the first drive amount as the second drive amount.

[0030] The difference between the first and second drive amounts is proportional to the HDR effect level in the HDR video data obtained by image synthesis. This is because the greater the difference between the drive amounts of the apertures 103a and 103b, the greater the difference in brightness between the two optical images formed by the first optical system 120a and the second optical system 120b, and the greater the difference in brightness between the two video data corresponding to these optical images (i.e., the HDR effect level).

[0031] In step S102, the lens control CPU 112 determines whether to allocate the first drive amount and the second drive amount to the aperture 103a or 103b. At this time, the lens control CPU 112 also corrects the position of the focus lens group 105a or 105b, as will be described later with reference to FIG.

[0032] In step S103, the lens control CPU 112 calculates the drive amount (first or second drive amount) of the aperture 103a. To obtain HDR video data through subsequent image synthesis, the drive amount of the aperture 103a is set to result in underexposure or overexposure relative to the correct exposure. Here, the drive amount of the aperture 103a is calculated to correspond to an aperture value that results in overexposure.

[0033] In step S104, the lens control CPU 112 calculates the drive amount (second or first drive amount) of the diaphragm 103b. Here, the drive amount of the diaphragm 103b is calculated so as to correspond to an aperture value that results in underexposure.

[0034] In step S105, the lens control CPU 112 drives the diaphragms 103a and 103b by the drive amounts calculated in steps S103 and S104 to change their aperture diameters. In this way, an overexposed optical image and an underexposed optical image are formed on the image sensor 201 by the light that has passed through the diaphragms 103a and 103b.

[0035] In step S106, the lens control CPU 112 communicates with the camera control CPU 206 and determines whether there has been a change in the first drive amount and the second drive amount (the difference from the first drive amount) for the apertures 103a and 103b. If there has been a change, the process returns to step S102; if there has been no change, the process proceeds to step S107. Examples of cases in which there has been a change in the first drive amount and the second drive amount include when the brightness of the subject changes during video capture and when the exposure conditions or HDR effect amount settings are changed by user operation. If the brightness of the subject changes, the first drive amount and the second drive amount change in the same way, and the difference between the first and second drive amounts does not change. On the other hand, if the exposure conditions or HDR effect amount settings are changed, the difference between the first and second drive amounts changes.

[0036] Here, we will explain the effect of capturing HDR video by differentiating the drive amounts (aperture values) of the apertures 103a and 103b. In this embodiment, by providing a difference in the drive amounts of the apertures 103a and 103b without using a neutral density filter, the exposures of the two video signals obtained by capturing video through the first optical system 120a and the second optical system 120b are made different. As described above, the HDR effect amount is proportional to the difference in the drive amounts of the apertures 103a and 103b. Unlike neutral density filters that must be attached to the interchangeable lens 100 before capturing video and have a fixed amount of light reduction, the apertures 103a and 103b do not require attachment before capturing video, and the difference in their drive amounts can be changed during video capture. Therefore, the HDR effect amount can be dynamically changed during video capture, enabling a wider variety of video expression than ever before.

[0037] In step S107, the lens control CPU 112 communicates with the camera control CPU 206 to determine whether video capture has ended. If video capture has not ended, the process returns to step S106, and the difference in the drive amounts of the diaphragms 103a and 103b continues to be changed in response to user operations until video capture ends in step S107. If video capture has ended, the process ends.

[0038] In this way, the overexposed video signal (first video data) obtained through the first optical system 120a and the underexposed video signal (second video data) obtained through the second optical system 120b are combined by the image synthesis processing circuit 209 and converted into HDR video data.

[0039] The two video signals obtained through the first and second optical systems 120a and 120b do not necessarily have to be overexposed and underexposed, but rather may have an exposure difference sufficient to combine HDR video data. For example, the video signals may be overexposed and properly exposed.

[0040] Next, the allocation of aperture values ​​to the first and second optical systems 120a and 120b and the focus adjustment operation (focusing) in this embodiment will be described with reference to Figures 3 and 4. In this embodiment, different aperture values ​​are set for the first and second optical systems 120a and 120b, which results in a difference in the depth of field between the first and second optical systems 120a and 120b.

[0041] Generally, focusing by driving a focus lens in an optical system has the characteristic that the shallower the depth of field, the better the focusing accuracy, so it is desirable to perform focusing using the optical system with the smaller aperture value and shallower depth of field between the first and second optical systems 120a and 120b.

[0042] Furthermore, when the aperture values ​​of the two optical systems are different, it is desirable to determine which optical system to use for metering. In this case, if the optical system that performs focusing is not the same as the optical system that performs metering, the metering accuracy and focusing accuracy will decrease.

[0043] Therefore, by assigning a smaller aperture value to the optical system that serves as the reference for focusing (hereinafter referred to as the focus reference optical system) out of the first and second optical systems 120a and 120b, it is possible to obtain good photometry accuracy and focusing accuracy.

[0044] Next, we will explain how to correct the position of the focus lens (focus position) relative to the aperture value. Generally, a change in aperture value causes focus movement, resulting in a change in the in-focus position. For this reason, if the focus position of the optical system that is not used as the reference for focusing (hereinafter referred to as the non-focus reference optical system) of the two optical systems is made the same as the focus position of the focus reference optical system, the difference in their aperture values ​​will reduce the focusing accuracy of the non-focus reference optical system.

[0045] For this reason, in this embodiment, the focus movement amount relative to the drive amount (change in aperture value) of the apertures 103a and 103b is stored as data in advance. Then, the focus position of the non-focus reference optical system is corrected according to the difference between the drive amount of the aperture of the non-focus reference optical system and the drive amount of the aperture of the focus reference optical system. This makes it possible to prevent a decrease in the focusing accuracy of the non-focus reference optical system.

[0046] 3 summarizes the above description in table form. Here, the first optical system 120a is used as both the photometry reference optical system for photometry and the focus reference optical system, and a drive amount is assigned to its aperture 103a to set a smaller aperture value than the aperture 103b of the second optical system 120b. The focus position of the non-focus reference optical system is corrected according to the difference in aperture value from the focus reference optical system.

[0047] The flowchart in FIG. 4 shows the process for allocating aperture values ​​to the apertures 103a and 103b and correcting the focus position of the non-focus reference optical system.

[0048] In step S201, the lens control CPU 112 reads out data on the amount of focus movement relative to changes in aperture value stored in the internal storage device 114, and calculates the amount of focus movement caused by the difference in aperture values ​​between the apertures 103a and 103b.

[0049] In step S202, the lens control CPU 112 determines whether the focus reference optical system is the first optical system 120a, and if it is the first optical system 120a, proceeds to step S203, and if it is the second optical system 120b, proceeds to step S205.

[0050] In step S203, the lens control CPU 112 assigns a first drive amount to the aperture 103a of the first optical system 120a, which is the focus reference optical system, and a second drive amount to the aperture 103b of the second optical system 120b, which is the non-focus reference optical system. The aperture value obtained with the first drive amount is smaller than the aperture value obtained with the second drive amount. The number of drive pulses is calculated in steps S103 and S104 of FIG. 2 according to the allocation of the drive amounts here.

[0051] In step S204, the lens control CPU 112 corrects the focus position of the second optical system 120b. Specifically, the lens control CPU 112 calculates the drive amount of the focus lens group 105b based on the focus movement amount calculated in step S201, and controls the focus drive circuit 111b so that the focus lens group 105b is moved by the drive amount. Then, this process ends.

[0052] On the other hand, in step S205, the lens control CPU 112 allocates a first drive amount to the aperture 103b of the second optical system 120b, which is the focus reference optical system, and a second drive amount to the aperture 103a of the first optical system 120a, which is the non-focus reference optical system. Here too, the aperture value obtained with the first drive amount is smaller than the aperture value obtained with the second drive amount.

[0053] In step S206, the lens control CPU 112 corrects the focus position of the first optical system 120a. Specifically, the lens control CPU 112 calculates the drive amount of the focus lens group 105a based on the focus movement amount calculated in step S201, and controls the focus drive circuit 111a so that the focus lens group 105a moves by the drive amount. Then, this process ends.

[0054] According to this embodiment, two pieces of video data with different exposures can be simultaneously acquired by setting different aperture values ​​for the first and second optical systems 120a and 120b. This allows the two pieces of video data to be combined together to be obtained without reducing the frame rate of the combined HDR video data. (Other Examples) The present invention can also be realized by supplying a program that realizes one or more functions of the above-described embodiments to a system or device via a network or a storage medium, and having one or more processors in the computer of the system or device read and execute the program.The present invention can also be realized by a circuit (e.g., ASIC) that realizes one or more functions.

[0055] The embodiments described above are merely representative examples, and various modifications and alterations are possible to each embodiment when implementing the present invention. [Explanation of symbols]

[0056] 100 Lens device (interchangeable lens) 120a First optical system 120b Second optical system 103a, 103b Aperture 105a, 105b Focus lens group 112 Lens control CPU 200 Imaging device (camera body) 202 Video signal processing circuit 209 Image synthesis processing circuit

Claims

1. A first optical system including a first aperture; a second optical system including a second aperture; a control means for controlling the driving of the first and second diaphragms; the optical axes of the first and second optical systems do not coincide with each other; 4. The optical device according to claim 1, wherein the control means controls the driving so as to make the aperture values ​​of the first and second apertures different from each other.

2. 2. The optical device according to claim 1, wherein the control means changes the difference in aperture value during video capture.

3. An optical device as described in claim 1 or 2, characterized in that each of the first and second optical systems includes a lens that moves during focusing.

4. The optical instrument described in Claim 3, characterized in that the control means determines whether or not the first optical system is a reference for focusing.

5. An optical device as described in claim 3 or 4, characterized in that the control means controls the drive so that the aperture value of one of the first and second optical systems, which is the basis for focusing, is smaller than the aperture value of the other optical system.

6. 6. The optical device according to claim 5, wherein the control means corrects the position of the lens in the other lens on the basis of data relating to a focus movement amount in response to a change in the aperture value.

7. An optical instrument described in any one of claims 3 to 6, characterized in that the control means controls the movement of the lens so as to make the positions of the lens in the first and second optical systems different from each other.

8. An optical device described in any one of claims 1 to 7, characterized in that it is detachable from an imaging device.

9. An optical device as described in any one of claims 1 to 7, characterized in that it has an imaging element that captures images via the first and second optical systems.

10. The optical device as described in Claim 9, characterized in that it has a processing means for generating video data having a wider dynamic range than each of the first and second video data generated by imaging via the first optical system and the second video data generated by imaging via the second optical system.

11. A method for controlling an optical device having a first optical system including a first aperture and a second optical system including a second aperture, comprising: A step of controlling the driving of the first and second diaphragms, the optical axes of the first and second optical systems do not coincide with each other; A control method comprising the steps of: controlling the driving so that the aperture values ​​of the first and second apertures are made different from each other.

12. A program characterized by causing a computer to execute processing in accordance with the control method described in claim 11.

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