JP6977559B2 - Imaging device and imaging method - Google Patents

Description

The present technology relates to an image pickup apparatus and an image pickup method, and more particularly to an image pickup apparatus and an image pickup method capable of F-drop correction.

Conventionally, it is known that even if the size of the aperture (iris) does not change in the image pickup apparatus, the brightness drops from the middle when the zoom position is moved to the telephoto side (hereinafter referred to as "F drop"). .. It is believed that this is because vignetting occurs somewhere in the lens due to the structure of the lens, which causes strain when approaching the telephoto end. For example, Patent Document 1 describes a technique for performing F-drop correction using F-drop characteristic data measured for each lens.

Japanese Unexamined Patent Publication No. 6-70229

An object of the present technology is to enable accurate F-drop correction without using F-drop characteristic data.

The concept of this technology is
A correction gain calculation unit that obtains the correction gain according to the zoom position information and aperture value information from the lens,
It is equipped with a gain correction unit that performs F-drop correction by multiplying the image pickup signal from the image sensor by the correction gain obtained by the correction gain calculation unit.
The correction gain calculation unit is
It is in an image pickup device that obtains the correction gain by using a parameter for approximating the F drop characteristic of the lens.

In the present technology, the correction gain calculation unit obtains the correction gain according to the zoom position information and the aperture value information from the lens. Then, the gain correction unit applies the correction gain obtained by the correction gain calculation unit to the image pickup signal from the image sensor to perform F-drop correction. In this case, the correction gain calculation unit obtains the correction gain using a parameter for approximating the F drop characteristic of the lens.

For example, the parameters may be configured to include a first parameter indicating the drop gain at the tele end of the F drop characteristic and a second parameter indicating the position of the break point when the F drop characteristic is approximated by a polygonal line. .. In this case, for example, the parameters may be configured to further include a third parameter indicating the drop gain at the break point of the F-drop characteristic.

As described above, in the present technology, the correction gain is obtained by using the parameter for approximating the F drop characteristic of the lens. Therefore, the F drop correction can be performed accurately without using the F drop characteristic data.

In the present technology, for example, a parameter acquisition unit for acquiring parameters may be further provided. In this case, for example, the parameter acquisition unit may be configured to acquire parameters based on the user's parameter adjustment operation. Further, in this case, for example, the parameter acquisition unit may acquire parameters based on an automatic parameter adjustment operation. By providing the parameter acquisition unit in this way, it is possible to acquire and use the parameters suitable for the type of the mounted lens.

Further, in the present technology, for example, a parameter holding unit for holding parameters may be further provided. In this case, for example, the parameter holding unit holds parameters for each lens type, and the correction gain calculation unit receives the corresponding parameter supply from the parameter holding unit based on the lens type information from the lens to obtain the correction gain. You may ask for it. By providing the parameter holding unit in this way, it is possible to efficiently acquire and use the parameters suitable for the type of the mounted lens.

Here, when the parameter corresponding to the parameter holding unit does not exist, a notification unit for notifying the user to that effect may be further provided. By providing the notification unit in this way, it is possible to urge the user to perform an operation of acquiring a parameter suitable for the type of the mounted lens.

According to this technique, F-drop correction can be performed accurately without using F-drop characteristic data. It should be noted that the effects described in the present specification are merely exemplary and not limited, and may have additional effects.

It is a block diagram which shows the configuration example of the camera system as an embodiment. It is a figure which shows an example of the parameter held in the parameter holding part. It is a figure which shows the change characteristic of the brightness (level) of an image pickup signal when the zoom position is moved from a wide side to a tele side with an aperture open. It is a figure which shows an example of the F drop characteristic of a lens at a plurality of aperture values (F value). It is an example of the F drop characteristic of a lens at a plurality of aperture values (F value), and is a figure which shows the case where the brightness is plotted logarithmically. It is a figure for demonstrating the maximum gain Gmax, the bending point position Xp, and the roundness R which are three parameters which approximate the F drop characteristic of a lens. It is a figure for demonstrating the calculation formula for obtaining the correction gain y (= CG) using three parameters, the maximum gain Gmax, the bending point position Xp, and the roundness R. It is a figure for demonstrating that the bending point position is changed according to the diaphragm value F when the diaphragm is not in the open state. It is a figure which shows the adjustment order of three parameters (maximum gain Gmax, bending point position Xp, roundness R). It is a figure for demonstrating an example of the procedure of a user's parameter adjustment operation. It is a block diagram which shows the other configuration example of a camera system.

Hereinafter, embodiments for carrying out the invention (hereinafter referred to as “embodiments”) will be described. The explanations will be given in the following order.
1. 1. Embodiment 2. Modification example

<1. Embodiment>
[Camera system configuration example]
FIG. 1 shows a configuration example of the camera system 10 as an embodiment. The camera system 10 includes a camera device 100, a lens device 200, a monitor 300, a waveform monitor 400, and a remote controller 500. The lens device 200 is attached to a lens mount portion (not shown) on the front portion of the camera device 100.

The lens device 200 has a zoom function and an aperture (iris) function. The user can change the zoom position and the aperture value (F value) by operating the operation unit of the camera device 100 or the remote controller 500. The change of the zoom position may be operated by a remote controller (not shown) directly connected to the lens device 200.

The camera device 100 includes an image sensor 101, a gain circuit 102, an image processing unit 103, an output terminal 104, an F drop correction gain calculation unit 105, a parameter setting unit 106, a parameter holding unit 107, and a display / operation. It has a part 108.

The image sensor 101 is composed of a CMOS image sensor or the like, and outputs an image pickup signal corresponding to the subject. The lens device 200 described above forms an image of a subject on the image pickup surface of the image sensor 101. The gain circuit 102 performs F-drop correction by multiplying the image pickup signal output from the image sensor 101 by the correction gain CG.

The image processing unit 103 performs camera signal processing such as white balance adjustment and gamma correction, which are well known in the past, on the image pickup signal output from the gain circuit 102, and outputs the image pickup signal as the output of the camera device 100 to the output terminal 104. do. The monitor 300 displays an image based on the image pickup signal output to the output terminal 104. The waveform monitor 400 is well known in the past. In this embodiment, the waveform monitor 400 processes the image pickup signal output to the output terminal 104 to display the brightness at each position in the horizontal direction. As will be described later, this display of the waveform monitor 400 is used when manually acquiring parameters for approximating the F drop characteristics of the lens.

The F-drop correction gain calculation unit 105 calculates the correction gain CG corresponding to the zoom position (x) and the aperture value (F) by using a parameter for approximating the F-drop characteristic of the lens. The F drop correction gain calculation unit 105 is given information on the zoom position (x) and the aperture value (F) from the lens device 200, and is also given information on the open (maximum) aperture value (Fo).

The parameter setting unit 106 provides the F drop correction gain calculation unit 105 with parameters for approximating the F drop characteristics of the lens in the open aperture state. This parameter includes the maximum gain (MAX GAIN) Gmax indicating the drop gain at the telephoto end of the F drop characteristic, the break point position (DROP POINT) Xp when the F drop characteristic is approximated by a polygonal line, and the above break point of the F drop characteristic. Three of the roundness (ROUNDNESS) R of the F drop characteristic curve indicating the decrease gain are included.

Depending on the type of lens, the F drop characteristic may be approximated by two parameters, the maximum gain Gmax and the break point position Xp. In that case, the parameter of roundness R becomes unnecessary. In the following description, a case where three parameters of maximum gain Gmax, bending point position Xp, and roundness R are required will be described.

The parameter holding unit 107 holds parameters for approximating the F-drop characteristics of the lens for each lens type (including the combination type when the lens and the extender are used in combination). The parameter holding unit 107 may be configured to store parameters in a semiconductor memory, for example, and the semiconductor memory may be detachable at that time.

FIG. 2 shows an example of the parameters held in the parameter holding unit 107. For example, the maximum gain = 6.0 dB, the bending point position = 85%, and the roundness = 1.0 dB are maintained corresponding to the combination of the lens type = lens A and the extender type = x1. Further, for example, the maximum gain = 10.6 dB, the bending point position = 72%, and the roundness = 0.8 dB are maintained corresponding to the combination of the lens type = lens B and the extender type = x2.

Information on the lens type (including the combination type when the lens and the extender are used in combination) is given to the parameter setting unit 106 from the lens device 200. The parameter setting unit 106 determines whether the parameter holding unit 107 holds the parameter of the lens type indicated by the lens type information given by the lens device 200. When holding, the corresponding parameter is taken out from the parameter holding unit 107 and given to the F drop correction gain calculation unit 105.

When not held, the parameter setting unit 106 displays, for example, on the display / operation unit 108 or the display unit of the remote controller 500 to notify the user, and acquires a parameter suitable for the type of the mounted lens. Prompt the user to adjust the parameters for this. This notification can be given not only by displaying an image but also by outputting voice. The details of this parameter adjustment operation will be described later.

"F drop characteristic approximation parameter of lens and correction gain calculation"
A parameter that approximates the F drop characteristic of the lens and the calculation of the correction gain CG using the parameter will be described. FIG. 3 shows the change characteristic of the brightness (level) of the image pickup signal when the zoom position is moved from the wide side to the tele side with the aperture open. As shown in the figure, the brightness drops from the middle. This phenomenon is F drop. In this sense, the brightness change characteristic as shown in FIG. 3 is referred to as an F drop characteristic. In addition, even when the aperture is in a state other than the open state, F drop occurs in the same manner.

FIG. 4 shows an example of the F-drop characteristic of the lens at a plurality of aperture values (F-numbers). Here, Fa is, for example, an F value when the aperture is open, and has a relationship of Fa <Fb <Fc <Fd <Fe <Ff <Fg. The brightness decreases as the aperture value increases, but F-drop occurs on the telephoto end side regardless of the F-number.

FIG. 5 shows the case where the brightness is logarithmically plotted with the F-drop characteristics of the lens at the plurality of aperture values (F-numbers) of FIG. From this figure, it can be seen that the brightness decreases linearly regardless of the F value. From this, it is expected that the zoom value is originally a logarithmic value. Further, from this figure, it can be seen that the roundness of the F drop characteristic curve is constant regardless of the magnitude of the F value.

From the above-mentioned tendency, as shown in FIG. 6, the F drop characteristic of the lens can be approximated by three parameters. As described above, the three parameters are the maximum gain (MAX GAIN) Gmax, which indicates the drop gain at the telephoto end of the F drop characteristic, the break point position (DROP POINT) Xp when the F drop characteristic is approximated by a polygonal line, and the F drop characteristic. It is the roundness (ROUNDNESS) R of the F drop characteristic curve which shows the drop gain at the said break point.

As described above, the parameter setting unit 106 to the F drop correction gain calculation unit 105 are provided with parameters for approximating the F drop characteristics of the lens in the open aperture state. The F drop correction gain calculation unit 105 obtains the correction gain y (= CG) by using the calculation formula shown in FIG. 7 according to the zoom position x in the aperture open state.

That is, the calculation formula in which the zoom position is between the zoom wide end position Xw = 0 and (Xp-4R / k) is y = 0. The calculation formula for the zoom position between (Xp-4R / k) and (Xp + 4R / k) is y = k ² {x− (Xp-4R / k)} ² / 16R. Further, the calculation formula for the zoom position between (Xp + 4R / k) and the zoom tele end position Xt is y = k (x−Xp). In addition, k = Gmax / (Xt-Xp).

Further, when the aperture is not open, the F drop correction gain calculation unit 105 changes the bending point position according to the aperture value F, as shown in FIG. In this case, the bending point position at the aperture value F is Xp + {40 (log ₁₀ F-log ₁₀ Fo) / k}, where Fo is the open aperture value. The F drop correction gain calculation unit 105 uses Xp + {40 (log ₁₀ F-log ₁₀ Fo) / k} instead of Xp in the calculation formula shown in FIG. 7, so that the correction gain y (correction gain y at the aperture value F) ( = CG) can be obtained.

"Parameter adjustment operation"
As described above, when the parameter setting unit 106 does not hold the parameter corresponding to the type of the lens to which the parameter holding unit 107 is mounted, the parameter setting unit 106 displays to that effect on the display / operation unit 108 or the display unit of the remote controller 500. Notifies the user and prompts the user to perform a parameter adjustment operation to acquire a parameter suitable for the type of the attached lens.

An example of the procedure of the parameter adjustment operation will be described. Here, the display / operation unit 108 is used as an example, but the same can be performed by using the remote controller 500. The user (operator) sequentially adjusts the three parameters while referring to the luminance display of the waveform monitor 400, the menu display of the display / operation unit 108, and the like. In this case, as shown in FIG. 9, adjustments are made in the order of (1) maximum gain Gmax, (2) break point position Xp, and (3) roundness R.

At the beginning of the adjustment start, as shown in FIG. 10A, the user operates the display / operation unit 108 to turn off the “F drop correction”. In this case, the correction gain CG given to the gain circuit 102 by the F drop correction gain calculation unit 105 is set to 0.0 dB. This F-drop correction off command is given to the F-drop correction gain calculation unit 105 through the parameter setting unit 106. The initial values of each parameter before adjustment are, for example, a maximum gain Gmax of 0.0 dB, a break point position Xp of 50%, and a roundness R of 0.0 dB.

Next, the user operates the display / operation unit 108 to open the aperture of the lens device 200, set the zoom position to the wide end, and image a white or gray object arranged at the center of the angle of view of the camera. do. At this time, as shown in FIG. 10B, the central luminance B in the luminance display of the waveform monitor 400 is maintained. This holding operation can be performed by the user operating the waveform monitor 400.

Next, the user operates the display / operation unit 108 to turn on (ON) "F drop correction" as shown in FIG. 10 (c). At this time, the F drop correction gain calculation unit 105 obtains the correction gain y (= CG) using the initial value of each parameter before adjustment given from the parameter setting unit 106, and gives it to the gain circuit 102.

Next, the user operates the display / operation unit 108 to set the zoom position to the telephoto end, and adjusts the maximum gain Gmax as shown in FIG. 10 (d). In this case, the F drop correction gain calculation unit 105 obtains the correction gain y (= CG) using the maximum gain Gmax that is sequentially adjusted and gives it to the gain circuit 102. The user adjusts the maximum gain Gmax so that the central brightness in the brightness display of the waveform monitor 400 matches the brightness B. In the illustrated example, the maximum gain Gmax is adjusted to 8.5 dB.

Next, the user operates the display / operation unit 108 to move the zoom position slightly (for example, about 10%) from the telephoto end to the wide end, and at the same time, as shown in FIG. 10 (e), the bending point position Xp is set. The adjustment is made as the state to be adjusted. In this case, the F drop correction gain calculation unit 105 obtains the correction gain y (= CG) using the break point position Xp that is sequentially adjusted and gives it to the gain circuit 102. In this case, the above-mentioned adjusted one is used as the maximum gain Gmax. The user adjusts the bending point position Xp so that the central brightness in the brightness display of the waveform monitor 400 matches the brightness B. In the illustrated example, the break point position Xp is adjusted to 79%.

Next, the user operates the display / operation unit 108 to move the zoom position from the wide end to the tele end, and determines the zoom position where the central brightness in the brightness display of the waveform monitor 400 is farthest from the brightness B. After finding it, as shown in FIG. 10 (f), the roundness R is adjusted as a state to be adjusted. In this case, the F drop correction gain calculation unit 105 obtains the correction gain y (= CG) using the roundness R that is sequentially adjusted and gives it to the gain circuit 102. In this case, the above-mentioned adjusted ones are used as the maximum gain Gmax and the break point position Xp. The user adjusts the roundness R so that the central brightness in the brightness display of the waveform monitor 400 matches the brightness B. In the illustrated example, the roundness R is adjusted to 2.5 dB.

Next, the user operates the display / operation unit 108 to hold each parameter of the maximum gain Gmax, the bending point position Xp, and the roundness R adjusted as described above in the parameter holding unit 107, and ends the adjustment. do. In this case, the parameter holding unit 107 holds each parameter in association with the type of the mounted lens. As a result, when the same type of lens is attached, it can be taken out from the parameter holding unit 107 and used.

The operation of the camera system 10 shown in FIG. 1 will be briefly described. A subject is imaged on the image pickup surface of the image sensor 101 of the camera device 100 by the lens device 200. Then, an image pickup signal corresponding to the subject can be obtained from the image sensor 101. This image pickup signal is supplied to the gain circuit 102.

Information on the lens type (including the combination type when the lens and the extender are used in combination) is given to the parameter setting unit 106 of the camera device 100 from the lens device 200. In the parameter setting unit 106, the lens type parameters (maximum gain Gmax, bending point position Xp, roundness R) indicated by the lens type information given by the lens device 200 are taken out from the parameter holding unit 107 or adjusted by the user. It is acquired by the operation and given to the F drop correction gain calculation unit 105.

The F drop correction gain calculation unit 105 of the camera device 100 is given information on the zoom position (x) and the aperture value (F) from the lens device 200, and also has information on the open (maximum) aperture value (Fo). Given. In the F drop correction gain calculation unit 105, the parameters (maximum gain Gmax, bending point position Xp, roundness R) given by the parameter setting unit 106 are used to correct the zoom position (x) and the aperture value (F). The gain CG is obtained and given to the gain circuit 102.

In the gain circuit 102, the correction gain CG is applied to the image pickup signal output from the image sensor 101 to perform F drop correction. The image pickup signal subjected to the F drop correction in this way is supplied to the image processing unit 103. The image processing unit 103 performs camera signal processing such as white balance adjustment and gamma correction, which are well known in the past, on the image pickup signal, obtains an output image signal from the camera device 100, and outputs the output image signal to the output terminal 104.

As described above, in the camera system 10 shown in FIG. 1, the camera device 100 uses the parameters (maximum gain Gmax, bending point position Xp, roundness R) for approximating the F drop characteristic of the lens, and the zoom position (roundness R). The correction gain CG corresponding to x) and the aperture value (F) is obtained, and F drop correction is performed. Therefore, the F drop correction can be performed accurately without using the F drop characteristic data.

Further, in the camera system 10 shown in FIG. 1, the camera device 100 acquires parameters (maximum gain Gmax, bending point position Xp, roundness R) suitable for the type of the lens to be mounted, based on the parameter adjustment operation of the user. can. Therefore, even if the parameters (maximum gain Gmax, bending point position Xp, roundness R) suitable for the type of lens mounted on the parameter holding unit 107 are not held, the parameters matched with the type of lens mounted. The correction gain CG can be obtained and used, and F-drop correction can be performed with high accuracy.

Further, in the camera system 10 shown in FIG. 1, the camera device 100 includes a parameter holding unit that holds parameters (maximum gain Gmax, bending point position Xp, roundness R) for each type of lens. Therefore, the parameters (maximum gain Gmax, bending point position Xp, roundness R) suitable for the type of the mounted lens can be efficiently acquired and used.

Further, in the camera system 10 shown in FIG. 1, when the camera device 100 does not have parameters (maximum gain Gmax, bending point position Xp, roundness R) suitable for the type of the mounted lens in the parameter holding unit 107, for example. , The display / operation unit 108 or the display unit of the remote controller 500 is displayed to that effect to notify the user. Therefore, it is possible to prompt the user to perform a parameter adjustment operation for acquiring a parameter suitable for the type of the mounted lens.

<2. Modification example>
In the above-described embodiment, the camera device 100 shows an example in which the maximum gain Gmax, the bending point position Xp, and the roundness R are used as parameters for approximating the F drop characteristic of the lens. However, instead of the two parameters of the maximum gain Gmax and the break point position Xp, it is also possible to use the two parameters of the slope k and the maximum gain Gmax, or the two parameters of the slope k and the break point position Xp. This is because there is a relationship of k = Gmax / (Xt-Xp).

Further, in the above-described embodiment, the user refers to the luminance display of the waveform monitor 400, the menu display of the display / operation unit 108, the remote controller 500, and the like, and three parameters (maximum gain Gmax, bending point position Xp, roundness R). By sequentially adjusting the above, it was configured to acquire the parameters suitable for the type of mounted lens.

A configuration in which this parameter adjustment operation is automatically performed is also conceivable. FIG. 11 shows a configuration example of the camera system 10A in that case. In this camera system 10A, the camera device 100 in the camera system 10 shown in FIG. 1 is replaced with the camera device 100A. In the camera device 100A, the display / operation unit 108 in the camera device 100 is replaced with the parameter automatic adjustment unit 109 and the brightness detection unit 110.

The luminance detection unit 110 processes the image pickup signal output to the output terminal 104 to detect the luminance (brightness) at each position in the horizontal direction, and sends the detection output to the parameter automatic adjustment unit 109. The parameter automatic adjustment unit 109 starts the adjustment operation based on the adjustment start instruction from the user (operator), and while referring to the detected luminance, sequentially performs the same operation as the user's parameter adjustment operation described above, and mounts the lens. The parameter corresponding to the type of the attached lens is acquired, and is held in the parameter holding unit 107 in association with the type of the mounted lens.

In addition, this technology can also have the following configurations.
(1) A correction gain calculation unit that obtains a correction gain according to the zoom position information and aperture value information from the lens.
It is equipped with a gain correction unit that performs F-drop correction by multiplying the image pickup signal from the image sensor by the correction gain obtained by the correction gain calculation unit.
The correction gain calculation unit is
An imaging device that obtains the correction gain using parameters for approximating the F-drop characteristics of the lens.
(2) The above parameters include
The image pickup apparatus according to (1) above, which includes a first parameter indicating a drop gain at the telephoto end of the F drop characteristic and a second parameter indicating a break point position when the F drop characteristic is approximated by a polygonal line.
(3) The above parameters include
The image pickup apparatus according to (2) above, further including a third parameter indicating a reduction gain at the break point of the F drop characteristic.
(4) The image pickup apparatus according to any one of (1) to (3) above, further comprising a parameter acquisition unit for acquiring the above parameters.
(5) The parameter acquisition unit is
The image pickup apparatus according to (4) above, which acquires the above parameters based on a user's parameter adjustment operation.
(6) The parameter acquisition unit is
The image pickup apparatus according to (4) above, which acquires the above parameters based on an automatic parameter adjustment operation.
(7) The image pickup apparatus according to any one of (1) to (6) above, further comprising a parameter holding unit for holding the above parameters.
(8) The parameter holding unit holds the above parameters for each type of lens.
The correction gain calculation unit is
The image pickup apparatus according to (7) above, wherein the correction gain is obtained by receiving the supply of the corresponding parameter from the parameter holding unit based on the information of the lens type from the lens.
(9) The image pickup apparatus according to (8), further comprising a notification unit for notifying the user when the corresponding parameter does not exist in the parameter holding unit.
(10) A correction gain calculation step for obtaining a correction gain according to the zoom position information and the aperture value information from the lens, and
It has a gain correction step that performs F-drop correction by multiplying the image pickup signal from the image sensor by the correction gain obtained in the correction gain calculation step.
In the above correction gain calculation step,
An imaging method for obtaining the correction gain using a parameter for approximating the F drop characteristic of the lens.

10,10A ... Camera system 100,100A ... Camera device 101 ... Image sensor 102 ... Gain circuit 103 ... Image processing unit 104 ... Output terminal 105 ... F drop correction gain calculation Unit 106 ・ ・ ・ Parameter setting unit 107 ・ ・ ・ Parameter holding unit 108 ・ ・ ・ Display / operation unit 109 ・ ・ ・ Parameter automatic adjustment unit 110 ・ ・ ・ Brightness detection unit 200 ・ ・ ・ Lens device 300 ・ ・ ・ Monitor 400・ ・ ・ Wave monitor 500 ・ ・ ・ Remote control

Claims (8)

A correction gain calculation unit that obtains the correction gain according to the zoom position information and aperture value information from the lens,
It is equipped with a gain correction unit that performs F-drop correction by multiplying the image pickup signal from the image sensor by the correction gain obtained by the correction gain calculation unit.
The correction gain calculation unit is
Obtain the correction gain using the parameters for approximating the F-drop characteristics of the lens.
The above parameters are
Two parameters of the drop gain at the tele end of the F drop characteristic and the break point position when the F drop characteristic is approximated by a polygonal line, the slope of the straight line on the telephoto end side when the F drop characteristic is approximated by the polygonal line, and the F drop. It includes two parameters of the drop gain at the tele end of the characteristic, or two parameters of the slope of the straight line on the tele end side and the position of the polygon when the above F drop characteristic is approximated by a polygonal line.
An image pickup apparatus including a parameter indicating a reduction gain at the break point of the F drop characteristic. The image pickup apparatus according to claim 1, further comprising a parameter acquisition unit for acquiring the above parameters. The above parameter acquisition unit
The image pickup apparatus according to claim 2 , wherein the above parameters are acquired based on a user's parameter adjustment operation. The above parameter acquisition unit
The image pickup apparatus according to claim 2 , wherein the above parameters are acquired based on an automatic parameter adjustment operation. The image pickup apparatus according to any one of claims 1 to 4 , further comprising a parameter holding unit for holding the above parameters. The parameter holding unit holds the above parameters for each type of lens.
The correction gain calculation unit is
The image pickup apparatus according to claim 5 , wherein the correction gain is obtained by receiving the supply of the corresponding parameter from the parameter holding unit based on the information of the lens type from the lens. The image pickup apparatus according to claim 6 , further comprising a notification unit for notifying the user when the corresponding parameter does not exist in the parameter holding unit. A correction gain calculation step for obtaining a correction gain according to the zoom position information and aperture value information from the lens, and
It has a gain correction step that performs F-drop correction by multiplying the image pickup signal from the image sensor by the correction gain obtained in the correction gain calculation step.
In the above correction gain calculation step,
Obtain the correction gain using the parameters for approximating the F-drop characteristics of the lens.
The above parameters are
Two parameters of the drop gain at the tele end of the F drop characteristic and the break point position when the F drop characteristic is approximated by a polygonal line, the slope of the straight line on the telephoto end side when the F drop characteristic is approximated by the polygonal line, and the F drop. It includes two parameters of the drop gain at the tele end of the characteristic, or two parameters of the slope of the straight line on the tele end side and the position of the polygon when the above F drop characteristic is approximated by a polygonal line.
An imaging method including a parameter indicating a reduction gain at the break point of the F drop characteristic.

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