Optical instrument and its control method

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 device having two optical systems arranged in parallel.

Background Art

[0002] High Dynamic Range (HDR) image data can be obtained by synthesizing under-exposed image data and over-exposed image data. However, in the conventional method of obtaining under-exposed image data and over-exposed image data by continuous imaging, HDR still image data can be obtained, but it is difficult to obtain video data.

[0003] Patent Document 1 discloses a method of obtaining frame image data of proper exposure, under-exposure, and over-exposure by changing the ISO sensitivity in video imaging through three consecutive imaging operations, and obtaining HDR video data including a frame image synthesized from these three frame image data.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] However, in the method disclosed in Patent Document 1, since three frame image data with different exposures are obtained by multiple imaging operations, the frame rate of the synthesized HDR video data becomes lower than the frame rate of video data obtained by normal imaging.

[0006] The present invention provides an optical device capable of obtaining a plurality of video data to be synthesized with each other so that the frame rate of the synthesized video data does not decrease.

Means for Solving the Problems

[0007] An optical instrument as one aspect of the present invention is a first aperture and the lens that moves during focusing A first optical system including and a second aperture and the lens that moves during focusing A second optical system including the first and second apertures Aperture value It has control means for controlling the first and second optical systems. The optical axes of the first and second optical systems are aligned with each other. not present. The control means is, The aperture value of one of the first and second optical systems, which is used as the focusing reference, is set smaller than the aperture value of the other optical system, so that the depth of field of the first optical system is shallower than the depth of field of the other optical system. It is characterized by doing so.

[0008] Another aspect of the present invention is the control method, A first optical system including a first aperture and a lens that moves during focusing, and a second optical system including a second aperture and a lens that moves during focusing. This is applied to optical instruments having the following: The control method is first and second Aperture value Control step The optical axes of the first and second optical systems do not coincide with each other. In the above step, the aperture value of one of the first and second optical systems, which is used as the focusing reference, is set to be smaller than the aperture value of the other optical system, so that the depth of field of the first optical system is shallower than the depth of field of the other optical system. The present invention is characterized by the fact that it causes a computer to execute a process according to the above control method. [Effects of the Invention]

[0009] According to the present invention, By using the optical system with the shallower depth of field (smaller aperture value) as the focusing reference, the focusing accuracy can be improved. It is possible. [Brief explanation of the drawing]

[0010] [Figure 1] A block diagram showing the configuration of the camera system including the interchangeable lens of Example 1. [Figure 2] A flowchart illustrating the process in Example 1. [Figure 3] A diagram illustrating the aperture setting and focus operation in Example 1. [Figure 4] A flowchart illustrating the focus process in Example 1. [Modes for carrying out the invention]

[0011] Hereinafter, embodiments of the present invention will be described with reference to the drawings. [Examples]

[0012] Figure 1 shows a camera system (imaging system) 10 comprising a lens device (hereinafter referred to as interchangeable lens) 100 as an optical instrument, which is an embodiment of the present invention, and an imaging device (hereinafter referred to as camera body) 200 to which the interchangeable lens 100 is attached in a way that allows for attachment and communication.

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

[0014] The variable magnification lens group 102a moves in the optical axis direction when a zoom ring (not shown) provided on the interchangeable lens 100 is rotated. As a result, the spacing between adjacent lens groups within the first optical system 120a changes, and magnification is achieved 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 aperture 103a is driven by an aperture actuator 106a, which is composed of a stepping motor or a DC motor, to change its aperture diameter (aperture value). The aperture drive circuit 107a supplies a drive signal to the aperture actuator 106a to drive it. The light intensity adjustment unit 116a is composed of the aperture 103a, the aperture actuator 106a, and the aperture drive circuit 107a.

[0016] The correction lens group 104a is driven in the shift direction orthogonal to the optical axis by an anti-shake actuator 108a such as a stepping motor or a voice coil motor, and reduces (corrects) image blur caused by camera shake such as hand shake. The anti-shake drive circuit 109a supplies a drive signal to the anti-shake actuator 108a. The 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 composed of a stepping motor, a voice coil motor, a vibration type motor, etc., moves in the optical axis direction, and performs focusing to bring the focus state closer to the in-focus state. The 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 labeled with the symbol obtained by changing the symbol a attached to the components of the first optical system 120a to b. Note that the aperture 103a and the focus lens 105a arranged in the first optical system 120a correspond to the first optical member that can be driven. Also, the aperture 103b and the focus lens group 105b, which are optical members having the same functions as the aperture 103a and the focus lens group 105a respectively, arranged in the second optical system 120b correspond to the second optical member.

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

[0019] The camera body 200 is provided with an imaging element 201 composed of a photoelectric conversion element such as a CCD sensor or a CMOS sensor. The imaging element 201 photoelectrically converts (images) optical images (subject images) respectively formed by the first optical system 120a and the second optical system 120b on its imaging surface. Specifically, an optical image is formed in the right region of the imaging element 201 for the light that has passed through the first optical system 120a, and an optical image is formed in the left region of the imaging element 201 for the light that has passed through the second optical system 120b. Thereby, two optical images can be imaged by the imaging element 201 without interfering the light that has passed through the first optical system 120a and the second optical system 120b with each other. The charges accumulated in the imaging element 201 are read out as analog imaging signals at a predetermined timing and input to the video signal processing circuit 202.

[0020] The video signal processing circuit 202 as image processing means converts the analog imaging signal read from the imaging element 201 into a digital imaging signal, performs various signal processes such as amplification and gamma correction on the digital imaging signal, and generates a digital video signal (moving image data). The digital video signal is output to a display device 205 composed of a camera control CPU 206, a liquid crystal display panel, etc. and a storage device 204 composed of an optical disk, a semiconductor memory, etc.

[0021] An AF signal processing circuit 203 is provided within the video signal processing circuit 202. The AF signal processing circuit 203 extracts high-frequency components and luminance components from the pixel group within the AF area, which is the focus detection area, 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 of the image (imaging contrast), that is, the sharpness, and changes as the focus lens groups 105a and 105b move. The focus position where the value of the focus evaluation value signal, that is, the focus evaluation value, is at its maximum (peak) becomes the focus position in that AF area.

[0022] Furthermore, an image synthesis processing circuit 209 is provided within the video signal processing circuit 202. 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 it into a video compatible with the VR180 video format, which has a field of view of 180°. The optical axes of the first optical system 120a and the second optical system 120b are spaced apart from each other by the baseline length in a direction perpendicular to each other, and the video signals obtained through the first optical system 120a and the second optical system 120b have parallax. By utilizing this parallax, a VR180 video that can be viewed in 3D can be generated. By observing the VR180 video through an observation device such as a head-mounted display, the user can see a three-dimensional image.

[0023] The image synthesis processing circuit 209 can also obtain VR180 video as a single, parallax-free video signal by separately converting multiple video signals obtained through the first optical system 120a and the second optical system 120b into VR180 format video signals and then synthesizing these video signals. For example, HDR video data can be generated by generating an overexposed video signal and an underexposed video signal through the first optical system 120a and the second optical system 120b, respectively, and then synthesizing these video signals. The image synthesis processing circuit 209 is not necessarily 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 memory device (storage means) 114. The internal memory device 114 stores table data indicating the amount of focus movement in relation to the amount of aperture stopping down from the wide-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 within 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 an AE (automatic exposure) unit (not shown) that measures the amount of light received from the subject.

[0026] The control unit 208 consists of multiple buttons, dials, and other operating elements. 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 equipped with operating elements for setting the image capture mode, issuing image capture instructions, and setting the HDR effect amount.

[0027] Figure 2 shows the processing (control method) that the lens control CPU 112 performs during video capture. The lens control CPU 112 performs this processing according to a computer program. In this embodiment, the case in which the lens control CPU 112 of the interchangeable lens 100 performs the processing is described, but the CPU of a lens-integrated imaging device (optical instrument) may also perform the same processing. In other words, 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 the first and second drive amounts for the apertures (first aperture, second aperture) 103a and 103b. The aperture drive amount here refers to the drive amount from the open position, which is the reference position of the aperture, and can be rephrased as the aperture value as the drive position. The first and second drive amounts may be directly input by the user in the camera body 200, or they 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 receives input regarding the first and second drive amounts (drive positions that have a difference from each other). The information regarding the first and second drive amounts may be the first and second drive amounts themselves, or it may be information that can be converted into the first and second drive amounts.

[0029] In the next step S102, it is determined which of apertures 103a and 103b the first and second drive values ​​are assigned to. For the second drive value, the CPU may receive the second drive value itself, or it may receive the difference between it and the first drive value. Here, the lens control CPU 112 receives the first drive value and also receives the difference between it and the first drive value as the second drive value.

[0030] The difference between the first and second drive amounts is proportional to the HDR effect amount in the HDR video data obtained by image synthesis. This is because the larger the difference in the drive amounts of 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 consequently, the greater the difference in brightness (i.e., the HDR effect amount) between the two video data corresponding to these optical images.

[0031] In step S102, the lens control CPU 112 determines which of the apertures 103a and 103b to assign the first and second drive amounts to. At this time, the lens control CPU 112 also corrects the position of the focus lens group 105a or focus lens group 105b, as will be explained later with reference to Figure 4.

[0032] In step S103, the lens control CPU 112 calculates the drive amount (first or second drive amount) for the aperture 103a. In order to obtain HDR video data through subsequent image synthesis, the drive amount of the aperture 103a is set to be either underexposed or overexposed 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) for the aperture 103b. Here, the drive amount for the aperture 103b is calculated to correspond to an aperture value that results in underexposure.

[0034] In step S105, the lens control CPU 112 drives the apertures 103a and 103b with the drive amounts calculated in steps S103 and S104 to change their aperture diameters. In this way, the light passing through apertures 103a and 103b forms an overexposed optical image and an underexposed optical image on the image sensor 201.

[0035] In step S106, the lens control CPU 112 communicates with the camera control CPU 206 to determine whether there is a change in the first drive amount and the second drive amount (the difference from the first drive amount) for apertures 103a and 103b. If there is a change, the process returns to step S102; otherwise, it proceeds to step S107. Changes in the first and second drive amounts occur when the brightness of the subject changes during video recording, or when the exposure conditions or HDR effect amount settings are changed by user operation. If the brightness of the subject changes, the first and second drive amounts 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 performing HDR video capture by making the drive amounts (aperture values) of apertures 103a and 103b different. In this embodiment, by creating a difference in the drive amounts of 103a and 103b without using a neutral density filter, the exposure of the two video signals obtained by imaging through the first optical system 120a and the second optical system 120b is made different. As mentioned above, the amount of HDR effect is proportional to the difference in the drive amounts of apertures 103a and 103b. Unlike neutral density filters, which require attachment to the interchangeable lens 100 before imaging and have a fixed amount of light reduction, apertures 103a and 103b do not require attachment before imaging, and the difference in their drive amounts can also be changed during video capture. Therefore, the amount of HDR effect can be dynamically changed during video capture, enabling a wider range of video expressions compared to conventional methods.

[0037] In step S107, the lens control CPU 112 communicates with the camera control CPU 206 to determine whether video recording has finished. If video recording has not yet finished, the process returns to step S106 and continues to change the difference in the drive amount of apertures 103a and 103b according to user operation until video recording is finished in step S107. If video recording is finished, this process ends.

[0038] Thus, 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] Furthermore, the two video signals obtained through the first and second optical systems 120a and 120b do not necessarily have to be overexposed and underexposed; any exposure difference that allows for the synthesis of HDR video data is sufficient. For example, an overexposed video signal and a properly exposed video signal would suffice.

[0040] Next, using Figures 3 and 4, the assignment of aperture values ​​and focusing operation for the first and second optical systems 120a and 120b in this embodiment will be explained. In this embodiment, different aperture values ​​are set for the first and second optical systems 120a and 120b, resulting in a difference in the depth of field of the first and second optical systems 120a and 120b.

[0041] Generally, focusing by driving the focusing lens of an optical system has the characteristic that focusing accuracy improves with a shallower depth of field. For this reason, it is desirable to perform focusing with the optical system of the first and second optical systems 120a and 120b that has a smaller aperture value and a shallower depth of field.

[0042] Furthermore, when the aperture values ​​of the two optical systems differ, it is desirable to determine which optical system to use for photometering. In this case, if the optical system used for focusing is not matched with the optical system used for photometering, the accuracy of photometering and focusing will decrease.

[0043] Therefore, by assigning a smaller aperture value to the optical system that serves as the focusing reference (hereinafter referred to as the focus reference optical system) among the first and second optical systems 120a and 120b, good photometric accuracy and focusing accuracy can be obtained.

[0044] Next, we will explain the correction of the focus lens position (focus position) in relation to the aperture value. Generally, changes in the aperture value cause a shift in focus and change the point of focus. For this reason, if the focus position of the optical system that is not used as the focusing reference (hereinafter referred to as the non-focus reference optical system) is set to be the same as the focus position of the focus reference optical system, the focusing accuracy of the non-focus reference optical system will decrease due to the difference in their aperture values.

[0045] Therefore, in this embodiment, the amount of focus shift in relation to the drive amount (change in aperture value) of 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 prevents a decrease in the focusing accuracy of the non-focus reference optical system.

[0046] Figure 3 summarizes the above explanation in a table format. Here, the first optical system 120a is used as both a photometric reference optical system for photometry and a focus reference optical system, and a drive amount is assigned to its aperture 103a to make it smaller than the aperture 103b of the second optical system 120b. In addition, the focus position of the non-focus reference optical system is corrected according to the difference in aperture value with that of the focus reference optical system.

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

[0048] In step S201, the lens control CPU 112 reads the data on the amount of focus shift in response to the change in aperture value stored in the internal memory device 114 and calculates the amount of focus shift caused by the difference in aperture values ​​between 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. If it is the first optical system 120a, the process proceeds to step S203; otherwise, it 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 in steps S103 and S104 of Figure 2 is calculated according to the assignment of drive amounts here.

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

[0052] Meanwhile, in step S205, the lens control CPU 112 assigns 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 again, 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, it calculates the amount of drive for the focus lens group 105a based on the amount of focus shift calculated in step S201, and controls the focus drive circuit 111a so that the focus lens group 105a moves by that amount. Then this process ends.

[0054] According to this embodiment, by making the aperture values ​​of the first and second optical systems 120a and 120b different from each other, two video data with different exposures can be acquired simultaneously. Therefore, the frame rate of the combined HDR video data can be obtained without lowering the frame rate of the two video data that are combined. (Other examples) The present invention can also be realized by supplying a program that implements one or more of the functions of the above-described embodiments to a system or device via a network or storage medium, and by having one or more processors in the computer of that system or device read and execute the program. It can also be realized by a circuit (e.g., an ASIC) that implements one or more functions.

[0055] The embodiments described above are merely representative examples, and various modifications and changes can be made to each embodiment when implementing the present invention. [Explanation of Symbols]

[0056] 100 Lens Device (Interchangeable Lenses) 120a First optical system 120b Second optical system 103a, 103b aperture 105a, 105b Focusing 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 and a lens that moves during focusing, A second optical system including a second aperture and a lens that moves during focusing, It has control means for controlling the aperture values ​​of the first and second apertures, The optical axes of the first and second optical systems do not coincide with each other. The control means is characterized by making the aperture value of one of the first and second optical systems, which is used as a focusing reference, smaller than the aperture value of the other optical system, so that the depth of field of the first optical system is shallower than the depth of field of the other optical system.

2. The optical device according to claim 1, characterized in that the control means changes the difference between the aperture values ​​of the first and second apertures during video capture.

3. The optical instrument according to claim 1 or 2, characterized in that the control means corrects the position of the lens in the other optical system based on data relating to the amount of focus shift in response to the change in aperture value.

4. The optical apparatus according to any one of claims 1 to 3, characterized in that the control means controls the movement of the lens so that the positions of the lens in each of the first and second optical systems are different from each other.

5. The optical instrument according to any one of claims 1 to 4, characterized in that it is detachable from an imaging device.

6. The optical device according to any one of claims 1 to 5, characterized in that it has an image sensor that performs imaging via the first and second optical systems.

7. A control method for an optical instrument having a first optical system including a first aperture and a lens that moves during focusing, and a second optical system including a second aperture and a lens that moves during focusing, The process includes a step of controlling the aperture values ​​of the first and second apertures, The optical axes of the first and second optical systems do not coincide with each other. A control method characterized in that, in the above step, the aperture value of one of the first and second optical systems used as a focusing reference is made smaller than the aperture value of the other optical system, such that the depth of field of the first optical system is shallower than the depth of field of the other optical system.

8. A program characterized by causing a computer to execute a process according to the control method described in claim 7.

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