JP2000196953A - Camera system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To make a lens interchangeable type camera applicable to a camera body having an image pickup element of a different configuration without increasing the size of a memory and, in addition, to enable the system to reduce the deterioration of picture qualities caused by shading. SOLUTION: This camera system is composed of an attachable/detachable interchangeable lens 10 and a camera body 40 to and from which the lens 10 can be attached and detached and can electrically pick up the image of an object. The camera body 40 performs shading correction on the body 40 based on the data about the position of the exit pupil of the lens 10, the stop value at the time of exposure, and the correction data peculiar to the camera body 40 at least corresponding to the stop value and the position of exit pupil.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a camera system in which a plurality of lenses can be exchanged.

[0002]

2. Description of the Related Art Conventionally, an electronic still camera such as a so-called digital camera which forms a subject image on an electric image pickup device by a lens and electrically records a still image has been known. In such a camera, a solid-state image sensor such as a CCD or a CMOS is used as an electric image sensor.

[0003] These solid-state imaging devices are integrally formed with a photosensitive portion, a light-shielding portion, a color filter for color imaging, and a cover, which are composed of photodiodes arranged on a matrix on a substrate.

However, the image pickup device having such a configuration has a poor aperture ratio of the photosensitive section and lowers the sensitivity. On the other hand, as shown in FIG. 13, an on-chip lens structure having a so-called micro lens is provided. Solid-state imaging devices have been put to practical use.

That is, the light incident through the on-chip microlens 1 passes through the color filter 2 and the substrate 3
Is guided to the photodiode 4 formed on the surface portion.
Thereby, the aperture is widened, and the light is condensed on the photodiode 4 as the photosensitive portion, so that the sensitivity of the solid-state imaging device can be improved. In FIG. 13, 5 is a vertical CCD, 6 is a transfer electrode, and 7 is a light shielding film.

However, when an image of a subject is formed on a solid-state image pickup device having such a configuration through a photographic lens, there is a problem that the periphery becomes dark, that is, so-called shading occurs.

That is, the incident angle of light incident on the solid-state image pickup device is different between the vicinity of the optical axis of the photographing lens and the light receiving portion on the side farther from the optical axis, so that the on-chip microlens 1 Vignetting occurs in the incident light due to the light performance and the color filter 2 and the light shielding film 7 of the solid-state image pickup device. For this reason, shading occurs due to a decrease in the sensitivity of the light receiving portion at a portion distant from the optical axis.

Further, the angle of incidence of the incident light incident on the solid-state image sensor changes depending on the exit pupil position of the photographing lens for forming the subject image on the solid-state image sensor and the stop.
Inevitably, shading differs depending on the exit pupil position of the taking lens and the aperture. Specifically, the longer the exit pupil distance is, the smaller the light amount drop (shading) in the peripheral portion is, and the narrower the aperture is (the larger the F value), the more the exit pupil distance is.
Peripheral light drop (shading) is reduced.

In the above-described example, the solid-state image pickup device having a built-in microlens has been described. Although the level is different from the element, shading occurs.

Regarding the above-described shading and the relationship between the shading and the aperture of the taking lens and the exit pupil distance,
For example, since it is described in detail in JP-A-5-283661 or the like, a detailed description thereof is omitted here.

[0011] By the way, in order to solve the above-mentioned problem, generally, a digital camera or a video camera with an integrated lens has
The influence of shading is reduced by making the configuration of the photographing lens an optical system having a small exit angle, that is, a so-called telecentric configuration.

On the other hand, in such a digital camera, an imaging lens for forming an image of subject light on a solid-state imaging device is replaceable, and various lenses are attached to and detached from a camera body having an imaging device. A system capable of photographing has been proposed. In these systems, depending on the photographic lens used, the focal length of the lens and the aperture value (F value)
And a shooting lens having a different exit pupil position distance of the shooting lens is used accordingly. Therefore, as described above, there is a problem that the level of shading differs depending on the lens used, and correction is difficult.

In a digital camera system having an interchangeable lens as described above, for example, Japanese Patent Application Laid-Open No.
A technique according to Japanese Patent No. 5485 is proposed. In the above publication, the taking lens has a shading correction coefficient corresponding to the type of lens or the aperture, transmits the correction coefficient to the camera body, and the camera body performs shading correction using the correction coefficient. Accordingly, an image without peripheral light quantity drop can be obtained even with different interchangeable lenses.

[0014]

However, the above-mentioned known examples are as follows.
It has the following problems.

First, since the shading correction data is used to correct the image of the image sensor, a large memory is required for the lens because it has a large amount of memory. Also, it takes time to transmit to the camera body.

Second, since the shading correction coefficient in the lens is a value corresponding to a certain (specific) camera body, a camera body incorporating an image sensor having a different configuration (for example, a camera body having a different number of pixels of the image sensor). In addition, there is a problem that it is not possible to cope with a camera body in which the configuration of the microlens is different or the imaging device does not have the microlens.

Furthermore, when a camera body having an image sensor having a different configuration is devised and mounted after the lens is released, shading correction cannot be performed with the lens, and the expandability of the system is limited. Have the problem of

The present invention has been made in view of the above problems, and is applicable to a camera body having an image pickup device of a different configuration without increasing the size of a memory in a camera system of an interchangeable lens type. It is another object of the present invention to provide a camera system capable of reducing a decrease in image quality due to shading.

[0019]

Means for Solving the Problems That is, the first invention is:
In a camera system including a detachable interchangeable lens and a camera body capable of detachably attaching the interchangeable lens and electrically capturing a subject image, the camera body relates to an exit pupil position of the interchangeable lens. The shading correction of the camera body is performed based on data, an aperture value at the time of exposure, and at least correction data unique to the camera body corresponding to the aperture value and the exit pupil position.

According to a second aspect of the present invention, there is provided a camera system including a detachable interchangeable lens and a camera body capable of detachably mounting the interchangeable lens and electrically capturing a subject image. Has data relating to the exit pupil position, and communication means for transmitting the data from the interchangeable lens to the camera body, wherein the camera body comprises:
Corresponding to the exit pupil position and the aperture value, having correction data unique to the camera body, the exit pupil position transmitted from the interchangeable lens by the communication means, the aperture value at the time of exposure,
The shading correction of the camera body is performed based on the correction data.

According to a third aspect of the present invention, there is provided a camera system comprising: a detachable interchangeable lens; and a camera body capable of detachably mounting the interchangeable lens and electrically capturing a subject image. Has exposure calculation means for determining an aperture value and a shutter speed at the time of exposure, and a plurality of program lines used for the exposure calculation, wherein the exposure calculation means is at least an exit pupil position of the interchangeable lens, or The program line is changed according to the focal length.

[0022]

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 is a block diagram showing the configuration of a digital camera system according to an embodiment of the camera system of the present invention.

In FIG. 1, the camera system includes an interchangeable lens 10 and a camera body 4 as a digital camera.
0.

The interchangeable lens 10 is composed of a zoom lens that can be attached to and detached from the camera body 40. In this embodiment, a 28-80 mm zoom lens is assumed as an example of the interchangeable lens. However, various interchangeable lenses such as a single focus lens, a telephoto lens, and a macro lens are conceivable. A photographic lens for forming a subject image includes four groups of lenses 11, 12, 13, and 14. An aperture mechanism 15 is arranged in the taking lens. A light beam from a subject (not shown) is guided to a movable mirror 41, which will be described later, in the camera body 40 via the photographing lenses 11, 12, the aperture mechanism 15, the photographing lenses 13, 14, and the aperture operation ring 16.

The states of the photographing lens 12, aperture mechanism 15, photographing lens 13 and aperture operation ring 16 are input to a lens control circuit 21 via a zoom encoder 17, an aperture encoder 20, a focus encoder 18 and an aperture ring encoder 19, respectively. Is done. The lens control circuit 21 includes a lens motor 25 via a zoom drive circuit 24, a focus motor 27 via a focus drive circuit 26,
An aperture motor 29 is connected via an aperture drive circuit 28, and each operates under the control of the lens control circuit 21. The lens control circuit 21 is connected to a lens switch input circuit 30, a nonvolatile memory 31, and a communication contact 33 via a communication line 32.

The photographing lens 12 includes a zoom drive circuit 2
4 is driven and controlled by a lens motor 25 which operates according to the output of FIG. The initial position and the stop position of the taking lens 12 are
Detected by the zoom encoder 17. Then, the detected position information is input to the lens control circuit 21 and fed back to the zoom drive circuit 24.

The drive of the aperture mechanism 15 is controlled by an aperture motor 29 that operates according to the output of an aperture drive circuit 28. The initial position and the stop position of the aperture mechanism 15 are detected by the aperture encoder 20. The position information detected here is input to the lens control circuit 21 and fed back to the aperture drive circuit 28.

The aperture operation ring 16 is for the camera operator to set the aperture. This aperture operation ring 16
Is detected by the aperture ring encoder 19, and the aperture set by the camera operator is detected.

The photographing lens 13 is driven and controlled by a focus motor 27 which operates according to the output of a focus drive circuit 26. The initial position and the stop position of the photographing lens 13 that change according to the focus drive are detected by the focus encoder 18. Then, the detected position information is input to the lens control circuit 21 and fed back to the focus drive circuit 26.

The lens control circuit 21 controls the zoom drive circuit 24, the focus drive circuit 26, and the aperture drive circuit 28 on the basis of the outputs of the zoom encoder 17, the focus encoder 18 and the aperture encoder 20, and also controls the overall control. Performs various necessary operations such as calculations. The lens control circuit 21 communicates with the camera body 40 as needed via the communication line 32 and the communication contact 33 to reflect the control of various circuits in the lens and to transmit the state of the lens to the camera body 40. It has become.
Here, the state of the lens means a nonvolatile memory 31 described later.
, The aperture setting value set in the aperture operation ring 16, the state of various lens switches, the state of the lens obtained through the various encoders, and the like.

The nonvolatile memory 31 stores data unique to the lens, and in this embodiment, is constituted by an EEPROM which is a rewritable nonvolatile memory. The data stored in the EEPROM is, for example, as shown in the following in-lens EEPROM data. Although only the number and the data name are shown here, a value representing the content of the data name in the lens is actually stored at each address of the EEPROM corresponding to the number.

[0033]

[Table 1]

In addition to the above Table 1, the EEP in the lens
The ROM stores data for calculating an exit pupil distance, which will be described later.

The lens switch input circuit 30 inputs the state of a lens switch (not shown) and transmits it to the lens control circuit 21. As a lens switch,
A zoom switch (not shown) corresponding to tele and wide is formed in the lens. When the tele-zoom switch is turned on by the camera operator, the lens control circuit 2
In 1, the zoom drive circuit 24 and the focus drive circuit 26 are controlled so that the focal length of the lens is set to the long focal length side in accordance with the ON operation by the lens switch input circuit 30.

Here, the reason why the focus drive circuit 26 is simultaneously controlled to perform the focus drive is that the interchangeable lens 10 is a so-called inner focus lens. This is because a shift occurs. Similarly, when the wide zoom switch is turned on by the camera operator, the lens control circuit 21 detects that the wide zoom switch is turned on through the lens switch input circuit 30, and changes the focal length of the lens to the short focal length in accordance with the on operation. , The zoom drive circuit 24 and the focus drive circuit 26 are controlled.

Next, the configuration of the camera body 40 will be described.

The subject light that has passed through the interchangeable lens 10 has a movable mirror 41 whose central portion is a half mirror.
Is incident on. A sub-mirror 42 is provided on the central rear surface of the movable mirror 41 so as to reflect the subject light downward. In the direction of the reflection optical axis of the sub-mirror 42 and in the vertical direction in FIG. 1, a separator optical system 43 for separating two images, which is composed of two optical systems,
Are arranged. Further, a line sensor 44 is provided at a position where the subject image is formed by the separator optical system 43.

In the body control circuit 55, the interval between the two images is obtained based on the signal input via the line sensor drive circuit 57, and the amount of the focus shift is determined via the communication line 65 and the communication contact 66 described later. It is transmitted to the lens control circuit 21 of the interchangeable lens 10. The lens control circuit 21 calculates the drive amount of the photographing lens 13 in the interchangeable lens 10 from the focus shift amount transmitted from the camera body 40 in order to drive the lens to the proper position. Then, focus adjustment is performed.

The sub-mirror 42, the separator optical system 43, the line sensor 44 and the like constitute a focus detecting device by a known phase difference method.

On the reflection optical path of the movable mirror 41, a focusing plate 46, a pentaprism 47 and a finder eyepiece optical system 48 are arranged. Behind the movable mirror 41, a shutter 50 and an optical low-pass filter 5 are provided.
1 and an image pickup device 52 for picking up a subject image and converting it into an image signal. When the movable mirror 41 is raised and the shutter 50 is opened, a subject image is formed on the image sensor 52, and the imaging is started by a predetermined timing signal. When the imaging is completed, the shutter 50
Is closed. The image sensor 52 may be constituted by a CCD or a CMOS image sensor.

The camera control circuit 55 controls the entire operation of the camera body 40.
6. Line sensor drive circuit 57, shutter drive circuit 5
8, photometric sensor drive circuit 59, shutter detection circuit 61,
The image processing circuit 62, the strobe circuit 63, and the switch input circuit 64 are connected.

The mirror driving circuit 56 includes a movable mirror 4
1 is driven to move in and out of the optical path. When the movable mirror 41 is in the optical path, the photographic light beam is guided toward the finder eyepiece optical system 48, whereas when the movable mirror 41 is retracted from the optical path, it is guided in the direction of the image sensor 52.

The line sensor drive circuit 57 is for driving the line sensor 44, and the shutter drive circuit 58 is for driving the shutter 50. Further, a photometric sensor 60 for measuring the luminance of the subject is provided above the finder prism 47 and the finder eyepiece optical system 48, and a photometric sensor driving circuit 59 is provided.
And the brightness of the subject light is measured.

The shutter detection circuit 61 includes a shutter 50
The image processing circuit 62 controls the operation of the image sensor 52. The subject image formed on the image sensor 52 is converted into an analog video signal by the image sensor 52, converted into a digital signal by the image processing circuit 62, and stored after being subjected to various processes. The details of the image processing circuit 62 will be described later.

The strobe circuit 63 is a flash light emitting means for illuminating the object, and operates as auxiliary light when strobe light emission is required. Also, the switch input circuit 6
Reference numeral 4 is for detecting the states of a plurality of switches such as various operation switches and inputting them to the camera control circuit 55.

Here, the various operation switches include, for example, a release switch, a mode switch and the like.
When the release switch is turned on by the camera operator,
The camera control circuit 55 detects this through the switch input circuit 64, and starts an exposure operation on the image sensor 52. When the mode switch is turned on by the camera operator, the camera control circuit 55 causes the switch input circuit 64 to operate.
Through which it is detected. The exposure mode of the camera is controlled in accordance with the number of times the shutter is turned on. Is set to one of the determined program modes.

When the interchangeable lens 10 is mounted on the camera body 40, the communication contact 6 for communicating with the interchangeable lens 10 via the communication line 65.
6 are connected. Further, a power supply 68 is provided in the camera body 40. The power supply 68 supplies power to each circuit in the camera body 40 and can also supply power to the interchangeable lens 10 via a communication contact.

FIG. 2 is a block diagram showing the configuration of the image processing circuit 62 described above. The image processing circuit 62 controls operations related to image processing under the control of a control unit controlled by the camera control circuit 55.

In FIG. 2, the subject image formed by the image pickup device 52 is converted into an analog video signal and output to the image processing circuit 62.

The image processing circuit 62 has a control section 71, an A / D conversion section 72, an image processing section 73, a buffer memory 74, an external memory (memory) 75, and a correction value memory 76. It is composed. The image processing unit 73, the buffer memory 74, the external memory 75, and the correction value memory 76 are connected by a common data bus 77, and have a configuration in which data can be exchanged. Further, the A / D converter 72, the image processor 72, the buffer memory 74, the external memory 75, the correction value memory 76
Is controlled by the control unit 71 controlled by the body control circuit 55 together with the imaging element 52.

The analog signal from the image sensor 52 is
After being converted into a digital signal by the A / D converter 72, the digital signal is supplied to the image processor 73. In this image processing unit 73,
Various corrections such as shading correction and color correction, and predetermined image processing including image compression and the like are performed using predetermined correction data stored in the correction value memory 76 in advance. After the signal processed by the image processing unit 73 is stored in the buffer memory 74, the signal is further stored in the external memory 7.
5 and recorded. The external memory 75 is attachable to the camera main body, is electrically rewritable, and retains the storage of the electronic image even when the power of the camera main body is turned off, and is used for recording the electronic image. . Here, the details of the shading correction will be described later,
The outline is as follows.

From the camera control circuit 55 to the image processing circuit 62
When the instruction for calculating the shading correction value is sent to the image processing unit 73, the correction data in the correction value memory 76 is used by the image processing unit 73 to execute the shading correction. Will be

When the program mode is used, the aperture value is determined on the camera body 40 side.
Is sent to the control unit 71 from the controller. On the other hand, in the aperture priority mode, since the interchangeable lens 10 has an aperture setting member, the set aperture value transmitted from the interchangeable lens 10 is sent from the camera control circuit 55 to the control unit 71. Similarly, the exit pupil distance transmitted from the interchangeable lens 10 is transmitted to the control unit 71. Details of these will be described later using each flowchart.

Next, the operation of the camera system will be described.

FIG. 3 is a flowchart for explaining the main operation of the camera system 40 on the camera body 40 side.

First, in step S1, initialization is performed by the camera control circuit 55, and in step S2, lens data is received. Then, in step S3, a display timer (not shown) is started. Thereafter, in step S4, it is determined whether the timer has expired. This timer is provided for shifting to the low power consumption mode when no operation of the camera is performed for a predetermined time.

If the timer has not expired, the flow shifts to step S5 to display the state of the camera on a display element such as an LCD (not shown). Next, step S6
It is determined whether or not the operation on the camera body 40 side has been performed. Then, when the operation is performed, the process proceeds to step S7, and the operation processing of the camera corresponding thereto is performed. If the camera is not operated in step S6, the process proceeds to step S8.

In step S8, it is determined whether or not a release button (not shown) of the camera has been operated. Then, when the release is operated, the flow shifts to step S9 to perform a release process. If the release process is not performed in step S8, and after the execution of step S9, the process returns to step S4.

On the other hand, if the timer has expired in step S4, the process proceeds to step S10 to enter the standby state of the low power consumption mode.

In the flowchart of FIG. 3, if there is communication from the lens after step S2, the latest lens data is always received because it is fetched at any time by interruption processing.

FIG. 4 is a flow chart for explaining the operation of the subroutine "release processing" in step S9 of the flow chart of FIG.

When the release process is performed, first, in step S21, focus detection is performed, and then, in step S2
At 2, the photographing lens is driven to the in-focus position. Further, in step S23, the lens state transmitted from the interchangeable lens 10 is received. The lens state is determined by the lens control circuit 21 based on inputs from the various encoders (the zoom encoder 17, the focus encoder 18, the aperture encoder 20, and the aperture ring encoder 19) in the lens described above and the input from the lens switch input circuit 30. This is data relating to the state of the lens, which is stored each time the state of the lens changes in a built-in RAM (not shown) which is a volatile memory. For example, as shown in the in-lens RAM data below, the exit pupil position, the set aperture value, the current focal length, and the current focus lens position are equivalent.

Here, the lens control circuit 21 derives and stores the exit pupil distance from the output of the zoom encoder 17 based on arithmetic or predetermined data. Similarly, the zoom encoder 17 and the focus encoder 18
, The current focal length and the current focus lens position are derived from the output of the aperture ring encoder 19, and stored as data.

[0065]

[Table 2]

Here, similarly to Table 1, in Table 2, the latest data corresponding to the contents of the data names in the order of the numbers in Table 2 are stored at predetermined addresses of the RAM incorporated in the lens control circuit 21 in the lens. Is stored.

Next, in step S24, photometry is performed to measure the luminance of the subject. And step S
At 25, it is determined whether the mode is the program mode or the aperture priority mode. Here, in the case of the program mode, the process proceeds to step S26, and in the case of the aperture priority mode, the process proceeds to step S26.
Move to 27.

If the process has proceeded to step S26, the program mode is set, so that the program diagram is obtained from the subject brightness obtained by the photometric processing in step S24 and the maximum aperture value, minimum aperture value received from the interchangeable lens 10, and the like. Is used to calculate the aperture and the shutter speed. The details will be described later.

On the other hand, when the process proceeds to step S27,
The shutter speed is calculated from the setting aperture already received from the interchangeable lens 10 and the subject luminance obtained in the photometry processing in step S24.

Next, at step S28, the exit pupil position and the aperture are transmitted to the image processing unit 73 in the image processing circuit 62. Here, in the case of the program mode, the exit pupil position transmitted from the interchangeable lens 10 side and the aperture value obtained by the exposure calculation are transmitted to the image processing unit 73.
Further, in the case of the aperture priority mode, the exit pupil position and the set aperture value transmitted from the interchangeable lens 10 side are stored in the image processing unit 7.
3 is sent.

After that, in step S29, the image processing unit 7 generates the data for shading correction.
The instruction for calculating the shading correction value is given to 3. Here, details of creation of shading correction data performed in the image processing circuit 62 using the transmitted exit pupil position and the diaphragm and shading correction using the shading correction data will be described later. Then, in step S30, the diaphragm is transmitted from the camera body 40 to the interchangeable lens 10 by communication. This is because in the program mode, the aperture is determined on the camera body 40 side.
The data is transmitted to the interchangeable lens 10 side.

Next, in step S31, the aperture driving is performed. In step S32, the movable mirror 41 is raised and retracted from the optical path.
When 0 is opened, an imaging instruction is issued. Then, in step S34, the process waits until the imaging is completed. When the imaging is completed and the shutter 50 is closed, the process proceeds to step S35. When the aperture is opened in step S35, the movable mirror 41 is lowered in the following step S36. Then, return.

FIG. 5 is a flowchart for explaining the operation of the subroutine "exposure calculation" in step S26 in the flowchart of FIG.

Since the above-described step S26 is executed in the program mode, first, step S4
At 1, an EV value, which is an exposure value obtained from the subject luminance and the characteristics of the image sensor 52, is calculated. Next, in step S42, the exit pupil distance is compared with a predetermined value.

Here, when the exit pupil distance is shorter than a predetermined value, that is, on the wide-angle side, peripheral dimming becomes extremely severe. In this case, when the aperture of the lens is opened, the peripheral dimming becomes more severe. Therefore, it is preferable to change the program diagram in a direction in which the aperture is further reduced in consideration of the exit pupil distance and the peripheral dimming. Therefore, in step S43, the aperture and the shutter speed are determined from the program diagram P2 shown in FIG.

On the other hand, if the exit pupil distance is larger than the predetermined value in step S42, the flow shifts to step S44 to determine the aperture and the shutter speed from the program diagram P1 shown in FIG. For example, if the EV value is 15
When the program diagram P1 is followed, the aperture is exposed at 5.6 at a shutter speed of 1/1000 sec. When the program diagram P2 is followed, the diaphragm is exposed at an aperture F8 and the shutter speed is 1/500 sec. Will be done.

The above-mentioned program diagrams P1, P2
Are set according to a general program diagram.

After the steps S43 and S44, the process returns.

As described above, by changing the aperture value at the time of exposure according to the exit pupil distance, an image with less influence of shading can be obtained.

Next, the main sequence of the interchangeable lens 10 will be described.

FIG. 7 is a flowchart for explaining the operation of the main sequence on the interchangeable lens 10 side.

First, when data is initialized in step S51, lens-specific data such as the maximum aperture value and minimum aperture value are transmitted from the interchangeable lens 10 to the camera body 40 in step S52. Is done.

Next, a timer is set in step S53, and the timer is started in step S54.
If the timer has expired in step S55, the process proceeds to step S69, in which standby preparation is performed, and then the device enters a standby state in which current consumption is reduced. On the other hand, if the timer has not expired in step S55,
In the following step S56, it is determined whether or not a lens operation has been performed.

If the lens operation has not been performed, the flow shifts to step S59. If the lens operation has been performed, the lens is driven according to the input from the lens switch input circuit 30 or the aperture ring encoder 19 in step S57, and the process proceeds to step S58. Now, the RAM where the lens status is stored
(Not shown) is updated.

In step S59, it is determined whether a communication request has been made from the camera body 40 side. Here, if there is no communication request, the process proceeds to step S68,
If there is a communication request, the process proceeds to step S60, where communication with the camera body 40 is performed.

Subsequently, in step S61, it is determined whether or not the communication content from the camera body 40 is a command. Here, if the communication content is a command, it is determined in step S62 whether the command is a lens operation command. The lens operation command is, for example, an operation command such as a focusing drive and an aperture drive.

At step S62, camera body 4
If the command transmitted from 0 is not a lens operation command, the process proceeds to step S63 and the corresponding command is executed. On the other hand, if it is determined in step S62 that the lens operation command has been transmitted, the process proceeds to step S62.
The flow shifts to 64, where the lens is driven in accordance with the command. After the above steps S63 and S64, step S65
Move to In this step S65, the above step S
Similarly to 58, the contents of the RAM in which the lens state is stored are updated.

Next, in step S66, the presence or absence of data transmission as a communication request from the camera body 40 is determined. If there is no data transmission, step S
Go to 68. On the other hand, if there is data transmission, the process proceeds to step S67, where the transmitted data is stored, and then proceeds to step S68.

Then, after the lens state transmission process is performed in step S68, the process returns to step S55.

FIG. 8 is a flowchart for explaining the operation of the subroutine "lens state transmission" in step S68 of the flowchart of FIG.

The above-described exit pupil distance is constant in the case of a single focus lens, but may vary depending on the zoom value in the case of, for example, a zoom lens. for that reason,
When the subroutine "lens state transmission" is entered, the exit pupil position is calculated in step S71 according to the state of the lens at that time. For example, in the case of a zoom lens, the exit pupil position is calculated from the focal length, lens-specific data, and the like.

In the present embodiment, the exit pupil position is
The nonvolatile memory 31 in the lens 10 (EEPRO
M) is obtained in accordance with a data table as shown in Table 3 below, which is stored unique to the lens. That is, the focusing lens position is Y1, and the set focal length is 35 to 50.
mm, the exit pupil distance is L2.

[0093]

[Table 3]

Next, in step S72, the RAM data of the lens state such as the calculated exit pupil position, set aperture value, current focal length, and current focus lens position is transmitted to the camera body 40 side. Then, return.

Here, a specific method of shading correction in this embodiment will be described in detail.

These operations are performed by the image processing section 62 in response to steps S28 and S29 in the flowchart of FIG. 4 described above, and are further performed in response to step S33 in the flowchart of FIG. Reference numeral 62 denotes a correction method performed in shading correction when imaging is performed.

In shading, as shown in FIGS. 9 and 10, the longer the exit pupil distance is, the smaller the drop in the amount of light in the peripheral area is. Less. That is, in the case of a short exit pupil distance, for example, in the case of a wide-angle lens, the peripheral dimming becomes large and the image becomes dark. (Here, the periphery is, for example, a point B that is farther from the optical axis than the point A corresponding to the optical axis O on the imaging surface, and the peripheral dimming increases as the distance D increases. .) The level of light intensity drop due to shading increases as the distance from the center of the optical axis on the imaging surface increases. In this embodiment, it is assumed that a plurality of shading correction curves are used with the distance d from the optical axis O as a variable as shown in FIG. 11 corresponding to each combination of the exit pupil distance and the stop. I have. In FIG. 10, only three curves are shown, but in reality, approximate curves exist for each combination of the exit pupil distance and the aperture.

In FIG. 10, the horizontal axis is the distance d from the optical axis, and the vertical axis is the shading in the form of the rate of decrease in the amount of light. In this embodiment, the approximate curve is
The equation is represented by f (d) = α + βd + γd ＾ 2, where the distance d is a variable, and α, β, and γ, which are coefficients of the approximate curve, are used as correction values corresponding to the respective approximate curves. The following correction value table 2 in the correction value memory 76 in advance
Is stored in Here, A to J are identification numbers corresponding to the respective approximate curves. At the time of the correction, first, in order to select an approximate curve, the approximate curve number corresponding to the exit pupil distance and the aperture transmitted in step S28 in the flowchart of FIG. Selected.

[0099]

[Table 4]

[0100]

[Table 5]

Here, the correction value table 1 stores the numbers of the approximate curves corresponding to each aperture and the exit pupil distance.
For example, when the aperture is F4 and the exit pupil distance is 55 mm, the approximate curve A33 is selected. It should be noted that the numerical values shown in the correction value table 1 are determined from design values, and are shown here by way of example.

Next, a correction value corresponding to the selected approximate curve is read from the correction value table 2. For example,
When the approximate curve A33 is selected, the correction values α33 and β3 corresponding to the approximate curve A33 are obtained from the correction value table 2.
3. γ33 is read.

Further, a correction value H corresponding to each pixel is created by the following approximate expression. Hxx = f (dxx) dxx: distance of the pixel located at the pixel position xx from the optical axis Hxx: correction value corresponding to the pixel whose distance from the optical axis is dxx As described above, each pixel is, as shown in FIG. Is generated as shown in the following correction value table 1 for each pixel.

[0104]

[Table 6]

Here, each pixel of the image pickup device 52 corresponds to FIG.
As shown in the figure, pixels 11 and 1
2, and so on. Then, in each pixel correction value table 1, for example, H001-001
, A correction value corresponding to the pixel 11 is stored in H001-002, and a correction value corresponding to each pixel is stored in H001-002.

The correction value table 1 of Table 6 contains 640
Each pixel correction value in a camera body having an image sensor of × 480 pixels is shown. However, in the case of a camera body having an image sensor having a different number of pixels or a camera body having a different image sensor, corresponding approximate curves, What is necessary is just to have the correction value table 1, the correction value table 2, and the correction value table corresponding to each pixel. As an example, Table 7 below shows the difference in the number of pixels (8
9 shows a correction value table in the case of (00 × 600 pixels).

[0107]

[Table 7]

In this embodiment, this correction value table is stored in the buffer memory 74, and when shading correction is performed on the output value of the image sensor 52 after the start of imaging, A / D conversion is performed on the output value of each pixel. After a predetermined process such as conversion is performed, correction is sequentially performed using a correction value corresponding to each pixel and a predetermined correction formula.

In the present embodiment, the correction value memory 7
In order to reduce the storage amount of No. 6, the correction is performed using the approximate curve as described above. For example, the correction value corresponding to the distance from each optical axis is separately stored without using the approximate curve. It is also possible to make a correction by storing as. In that case, more accurate correction can be made.

Further, when there is room in the capacity of the correction value memory 76, it is possible to perform correction by storing in advance the correction value of each pixel corresponding to each exit pupil distance and aperture. In that case, there is no need to calculate the correction value by calculation,
Time can be reduced.

Further, it is also possible to change the correction according to the image quality mode of photographing. For example, in the case of an image quality mode of low image quality, a method of simplifying the correction and the like can be considered.
In this case, unnecessary correction is not performed by changing the correction according to the image quality mode, so that the time required for the correction and the memory can be used efficiently.

According to the above embodiment of the present invention,
The following configuration can be obtained.

(1) In a camera system including a detachable interchangeable lens and a camera body capable of detachably mounting the interchangeable lens and electrically capturing an image of a subject, the camera body includes the interchangeable lens. The data relating to the exit pupil position of the lens, the aperture value at the time of exposure, the means for controlling the aperture of the interchangeable lens, a memory holding data unique to the camera body, and at least the aperture value and the exit pupil position, A first correction data unique to the camera body held in a memory, and correction data generating means for generating the second correction data used for correction calculation based on the first correction data; A camera system, wherein the generation unit generates the data while driving the aperture driving unit of the interchangeable lens.

(2) In a camera system including a detachable interchangeable lens and a camera body capable of detachably attaching the interchangeable lens and electrically capturing a subject image, the interchangeable lens has a focal length Detecting means, a focusing lens for focus adjustment, a second detecting means for detecting a position of the focusing lens, and at least an output of the first detecting means and an output of the second detecting means. Setting means for setting exit pupil distance data of the interchangeable lens, and communication means for transmitting the data from the interchangeable lens to the camera body,
A camera system, wherein the camera body performs shading correction of the camera body based on the exit pupil distance data transmitted from the interchangeable lens.

(3) A photographing lens that is interchangeable and can communicate with the mounted camera body, and a photographing lens on which the photographing lens can be mounted and which can communicate with the mounted photographing lens. In a camera system including a camera body that electronically captures a formed subject image, the camera body includes a camera body-specific correction data regarding an aperture value at the time of shooting and an exit pupil position of the shooting lens. By receiving the exit pupil position of the taking lens through communication with the taking lens, referring to the exit pupil position of the taking lens and the aperture value at the time of photographing, performing shading correction processing of the taken image based on the correction data. A camera system characterized in that it is performed.

(4) A camera having an image pickup element integrated with a photographing lens, comprising a storage means for storing image quality correction data unique to the image pickup element, a focal length of the photographing lens, an exit pupil position, and a photographing time. A camera comprising: image quality correction means for reading out appropriate image quality correction data from the storage means based on an aperture value and performing image quality correction processing of an output signal of the electronic imaging element.

(5) The camera according to (4), wherein the image quality correction processing is shading correction processing.

[0118]

As described above, according to the present invention, in a camera system of an interchangeable lens type, the present invention can be applied to a camera body having an image sensor having a different configuration without increasing the memory capacity. In addition, it is possible to provide a camera system capable of reducing a decrease in image quality due to shading.

[Brief description of the drawings]

FIG. 1 is an embodiment of a camera system according to the present invention;
FIG. 1 is a block diagram illustrating a configuration of a digital camera system.

FIG. 2 is a block diagram showing a configuration of an image processing circuit 62 of FIG.

FIG. 3 is a flowchart illustrating a main operation of a camera body 40 of the camera system.

FIG. 4 is a flowchart illustrating an operation of a subroutine “release process” in step S9 of the flowchart in FIG. 3;

FIG. 5 is a flowchart illustrating an operation of a subroutine “exposure calculation” in step S26 of the flowchart in FIG. 4;

FIG. 6 is a program diagram applied to an embodiment of the present invention.

FIG. 7 is a flowchart illustrating an operation of a main sequence on the interchangeable lens 10 side.

FIG. 8 is a flowchart illustrating an operation of a subroutine “lens state transmission” in step S68 of the flowchart in FIG. 7;

FIG. 9 is a characteristic diagram showing a relationship between an exit pupil distance and shading.

FIG. 10 is a characteristic diagram in a correction method according to the present embodiment using a relationship between a distance from an optical axis and shading.

FIG. 11 is a diagram illustrating a plurality of shading correction curves using a distance d from the optical axis O as a variable.

FIG. 12 is a diagram schematically showing an arrangement of each pixel in an image sensor 52.

FIG. 13 is a cross-sectional view showing a schematic configuration of a conventional solid-state imaging device having an on-chip lens structure to which a microlens is added.

[Explanation of symbols]

 Reference Signs List 10 interchangeable lens, 11, 12, 13, 14 lens, 15 aperture mechanism, 16 aperture operation ring, 17 zoom encoder, 18 focus encoder, 19 aperture ring encoder, 20 aperture encoder, 21 lens control circuit, 24 zoom drive circuit, 26 Focus drive circuit, 28 aperture drive circuit, 30 lens switch input circuit, 31 non-volatile memory, 40 camera body, 41 movable mirror, 42 sub-mirror, 43 separator optical system, 44 line sensor, 48 finder eyepiece optical system, 50 shutter, 52 Image sensor, 55 Camera control circuit 56 Mirror drive circuit, 57 Line sensor drive circuit, 58 Shutter drive circuit, 59 Photometry sensor drive circuit, 61 Shutter detection circuit, 62 Image processing circuit, 63 Strobe circuit, 64 Switch input times , 68 power supply, 71 control unit, 72 A / D conversion unit, 73 image processing unit, 74 buffer memory, 75 external memory (memory), 76 correction value memory, 77 data bus.

Continued on the front page F term (reference) 2H054 AA01 BB08 5C021 PA80 PA85 XA67 YC03 YC13 5C022 AA13 AB12 AB21 AB36 AB44 AB51 AC42 AC54 AC55 AC69 AC74 AC78 CA00 5C024 AA01 BA01 CA12 CA33 EA03 EA04 FA01 GA01 GA11 HA14 HA23

Claims (4)

[Claims] 1. A camera system comprising: a detachable interchangeable lens; and a camera body capable of detachably attaching the interchangeable lens and capable of electrically capturing a subject image, wherein the camera body includes the interchangeable lens. The shading correction of the camera body is performed based on the data on the exit pupil position, the aperture value at the time of exposure, and the camera body-specific correction data corresponding to at least the aperture value and the exit pupil position. Camera system. 2. A camera system comprising: a detachable interchangeable lens; and a camera body capable of detachably attaching the interchangeable lens and electrically capturing a subject image, wherein the interchangeable lens has an exit pupil position. And communication means for transmitting the data from the interchangeable lens to the camera body, wherein the camera body has camera body-specific correction data corresponding to the exit pupil position and the aperture value, A camera system for performing shading correction of the camera body based on the exit pupil position transmitted from the interchangeable lens by the communication means, an aperture value at the time of exposure, and the correction data. 3. The camera system according to claim 1, wherein the correction data is shading correction data according to characteristics of an image sensor of a camera body. 4. A camera system comprising: a detachable interchangeable lens; and a camera body, wherein the interchangeable lens is detachable, and which can electrically capture a subject image. An exposure calculation unit for determining an aperture value and a shutter speed; and a plurality of program lines used for the exposure calculation, wherein the exposure calculation unit is provided at least according to an exit pupil position or a focal length of the interchangeable lens. A camera system, wherein the program line is changed.