JP2783553B2 - Automatic focusing device, lens unit and camera device - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a camera device including a camera body and a lens system detachable from the camera body, and optimizes control contents according to lenses having different characteristics. Accordingly, the present invention relates to an automatic focusing device (hereinafter, referred to as an AF system) configured to obtain substantially the same distance measurement performance for any lens.

(Background art) Conventional video camera AF systems have an AF sensitivity and AF sensitivity that can provide sufficient distance measurement performance in accordance with the holding properties (for example, focal length, aperture value, etc.) of the shooting lens mounted on the camera. , The details of the speed control of the AF motor (of the driving means of the lens group for focus adjustment) were determined. However, in the case of a system in which the lens is interchangeable, various characteristics are different for each lens, so that optimization according to some lens characteristics is required. If this point is not realized well, (1) AF performance deteriorates due to changes in various characteristics of the lens.
Specifically, there is a concern about an operation such as an extremely slow operation for focusing, or an inability to stop the hunting operation in the vicinity of focusing.

(2) Problems such as the inability to realize a system that can respond to different types of AF methods occur, and eventually the system lacks versatility.

As a means for solving the above problems, Japanese Patent Application No. 63-189815 has been filed by the same applicant. Japanese Patent Application No. 63-18
In 9815, microcomputers are provided on both the lens side and camera side, and they are configured to communicate data with each other, and then drive means for moving the lens group for focus adjustment, such as an AF motor The microcomputer calculates a change amount ΔZ of a circle of confusion that changes by a predetermined rotation (for example, rotation of one pulse of a detection pulse board such as a rotation phase) based on the focal length f and the aperture value F. Transmission from the camera side to the camera side is performed via a mount selection contact. The microcomputer on the camera reads this value, and controls the operation of the AF signal processing circuit according to the degree of blur (focus, large blur, medium blur, small blur, etc.) determined by the AF signal processing circuit. Select the optimal confusion circle expansion speed. Then, an instruction for the AF motor rotation speed is given to the driving means on the lens side based on ΔZ so that the speed becomes the selected speed. In other words, in order for the AF system to function properly even when the lens characteristics change, the relationship between the speed of change of the circle of confusion and the degree of blurring must always be constant, not the rotational speed of the driving means. There is.

However, as shown in Japanese Patent Application No. 63-189815, when the focal length is short and the aperture value is large (smaller aperture value), the speed of change of the circle of confusion is constant as in other conditions. If used as is, very high-speed movement may be required. In such a case, the maximum speed in a practically acceptable range is substituted.

Let's show the above idea as an equation. In the case of a normal four-unit zoom lens, the first lens unit and the front lens unit are used for focus adjustment. Assuming that the focal length of the first group is f _F , the position sensitivity of the front lens at the telephoto end (focal length f _T )
S ₀ is represented by S ₀ = (f _T / f _F ) ² . The position sensitivity S at an arbitrary f is S = S × ₀ (f / f _T ) ² . Assuming that the lens group for focus adjustment moves by ΔA in the optical axis direction and the aperture value at this time is F, the change amount ΔZ of the circle of confusion changed by ΔA is ΔZ = ΔA × S ₀ × (f / f _T ) 2 / F. That is, to make the expansion speed of the circle of confusion constant according to the state of the blur means to make ΔZ a certain value at a certain time t. For that purpose, S ₀ and f _T Is a constant, so that ΔA is variable in accordance with the focal length f and the aperture value F. That is, ΔA = f (ΔZ, f, F), where ΔZ is a value defined by the AF signal processing circuit according to the degree of the blur.

As described above, ΔA at t (sec), that is, ΔA / t (mm
/ sec), it is necessary to change the moving speed of the lens group for focus adjustment depending on the focal length f, the aperture value F, and the degree of blurring on an AF system in a camera or the like employing an interchangeable lens.

(Problems to be Solved by the Invention) However, the method of Japanese Patent Application No. 63-189815 described above
Further research and development has indicated that there is still room for improvement. That is, Japanese Patent Application No. 63-189815
In the reference, the amount of change in the circle of confusion due to the predetermined rotation of the motor according to the focal length f and the aperture value F is calculated by the lens microcomputer.

However, in consideration of an interchangeable lens system, it is generally considered that a plurality of lens units are attached to and detached from a camera body.

Therefore, it is not preferable to provide the lens side with various arithmetic functions, and it is desirable that the lens side control means be simple.In such an interchangeable lens system, many functions are provided to the camera microcomputer. It should be focused.

(Means for Solving the Problems) The present invention has been made to solve the above problems, and according to the invention described in claim (1), the lens unit is attached to and detached from the camera body. In a possible camera device, focus detection means for detecting a focus state of a subject image formed by the lens unit, and characteristic detection for detecting optical property information on sensitivity of a position of a focus lens in the lens unit Means, and control means for moving the focus lens in the lens unit to a focal point based on the output of the focus detection means and the optical property information of the property detection means, wherein the control means comprises:
The confusion circle change speed accompanying the movement of the focus lens is determined based on the optical characteristic information, a plurality of speed control information of the focus lens is defined based on the confusion circle change speed, and the speed control information is defined based on the speed control information. An automatic focus adjustment device configured to drive a focus lens is featured.

According to the invention described in claim (2), in a camera device to which a lens unit is detachable, focus detection means for detecting a focus state of a subject image formed by the lens unit, and the lens unit From the side, a characteristic detecting means for detecting optical characteristic information relating to the sensitivity of the position of the focus lens in the lens unit, and an inside of the lens unit based on an output of the focus detecting means and optical characteristic information of the characteristic detecting means. And control means for calculating control information for moving the focus lens to a focal point and supplying the control information to the lens unit, wherein the control means controls the movement of the focus lens based on the optical characteristic information. The speed of change of the circle of confusion is determined, and a plurality of pieces of speed control information of the focus lens are defined based on the speed of change of the circle of confusion. Wherein the configured camera device so as to drive the focus lens on the basis of the control information.

According to the invention described in claim (3), a lens unit detachable from the camera unit, wherein the characteristic output means outputs optical characteristic information relating to the sensitivity of the position of the focus lens in the lens unit; The focus lens is focused on the basis of control information calculated from the degree-of-focus information detecting the focus state of the subject image formed by the lens unit and the optical characteristic information output by the characteristic output means. A control output for moving to the focal point, wherein the control information obtains a speed of change of a circle of confusion associated with the movement of the focus lens based on the optical characteristic information, and a plurality of the focus lenses based on the speed of change of the circle of confusion. Lens unit which is information for driving the focus lens based on the speed control information. And it features.

According to the invention described in claim (4), in a camera system including a camera main body and a lens unit detachable from the camera main body, a focus state of a subject image formed by the lens unit is detected. Focus detection means for detecting, a characteristic detection means for detecting optical characteristic information on the sensitivity of the position of the focus lens in the lens unit, and an output of the focus detection means and optical characteristic information of the characteristic detection means. Control means for moving the focus lens in the lens unit to a focal point,
The control means obtains a confusion circle change speed accompanying the movement of the focus lens based on the optical characteristic information, defines a plurality of speed control information of the focus lens based on the confusion circle change speed, and performs the speed control. A camera system configured to drive the focus lens based on information is characterized.

(Operation) By this, the driving speed of the predetermined optical system for performing the focus adjustment is defined by the change speed of the circle of confusion of the lens unit. Drive speed control can be commonly performed.

(Embodiment) Hereinafter, an automatic focusing apparatus according to the present invention will be described in detail with reference to the drawings, taking as an example a case where the apparatus is applied to a video camera or the like.

1 to 11 show an embodiment of the present invention.

FIG. 1 is a block diagram showing a case where the AF system of the present invention is applied to a video camera.

In the figure, reference numeral 1 denotes a lens unit including a lens system, 2 denotes a camera unit including an automatic focusing circuit according to the present invention, 3 denotes a focusing lens,
4 is an aperture, 5 is a zooming lens, 6 is an encoder that detects the position of a focusing lens, 7 is an encoder that detects the value of the aperture, 8 is an encoder that detects the position of the zooming lens, and 9, 10, and 11 are focusing lenses, respectively. , Aperture, transmission path for transmitting the output of encoders 6, 7, 8 for detecting the position of the zooming lens to a microcomputer 12 for control in the lens.
A microcomputer 13 which correctly drives the focusing 3 and the zooming lens 5 and the aperture 4 according to a driving command transmitted from the camera (to be described later), and transmits a driving result and various data of the lens to the camera microcomputer 16; A transmission path for transmitting each information from the lens microcomputer 12 to the camera microcomputer 16, a transmission path 14 for transmitting each information from the camera microcomputer 16 to the lens microcomputer 12, and a camera 15 2 shows a mount section for connecting the lens section and the lens section. 16 is to form a focused image of the subject on the imaging surface,
A camera microcomputer 17 having an automatic focus (AF) control function for issuing a drive command to the lens microcomputer 12, and a focusing lens 3, an aperture 4, and a driving unit 20, 21, A transmission path for transmitting a drive command from the lens microcomputer 12 to 22. Each of the drive circuits 20, 21, and 22 respectively, according to a drive command from the lens microcomputer 12,
The focusing lens 3, the diaphragm 4 and the zooming lens 5 are driven. Reference numeral 23 denotes an imaging device that has an imaging surface, converts an object image formed on the imaging surface by a lens into an electric signal, 24 denotes a transmission path that transmits a video signal obtained by the imaging device 23, and 25 denotes an imaging device. The signal output from 23 is
For example, a signal processing block for focus detection (AF) that converts the amount of high-frequency components and the number of edges into a content suitable for automatic focus detection processing, 26 is a zoom switch for moving a zooming lens, 27 is a subject, 28 Is a fixed relay lens, 29
Reference numeral denotes an aperture control circuit that controls an aperture value such that the luminance signal level becomes constant based on information from the image sensor 23, for example, information on the luminance signal level, to an optimum value.

Reference numeral 30 denotes a signal output from the image sensor 23, for example, gamma correction, blanking processing, addition of a synchronization signal, etc.
This is a video signal processing circuit that performs predetermined signal processing and outputs a standard television signal from a video output terminal Vout.

With the above configuration, the image of the subject 27 passes through the focusing lens 3 and is formed on the imaging surface of the imaging element 23 via the zooming lens group 5, the diaphragm 4, and the relay lens. At this time, the zooming lens 5 is set by the photographer using the zoom switch 26.
Can be set to a desired position within the movable range. The position of the zooming lens 5 is detected by the zoom encoder 8 and supplied to the lens microcomputer 12 via the transmission path 11 as position information.

The aperture 4 is controlled so that the light amount in the image sensor 23 is constant.
That is, as described above, the aperture control circuit 29 controls the signal output from the image sensor 23 so that the level of the signal becomes constant. This control signal is sent to the camera microcomputer 16 and translated, communicated to the lens microcomputer 12 via the transmission path 14, and the aperture drive circuit 21 performs automatic exposure adjustment. The aperture value is always detected by the encoder 7, read by the lens microcomputer 12 via the transmission path 10, and the above control is repeated.

Now, the video signal corresponding to the subject image output from the imaging element 23 is converted into a signal corresponding to the degree of focus by the AF signal processing circuit 25, for example, a signal indicating the amount of high frequency components in the video signal,
It is determined whether the object is in focus or out of focus. The level of the signal corresponding to the degree of focusing, that is, the level of the high-frequency component, has a maximum at the focal point and decreases as the distance from the focal point increases. In the present invention, the threshold level is set at a plurality of levels with respect to the level of the high-frequency component corresponding to the degree of focus,
If it is out of focus, how much it is deviated from the in-focus point, that is, the amount of blur is detected by comparing the plurality of threshold levels with the level of a high-frequency component corresponding to the degree of focus. I have.

FIG. 2 shows an AF signal processing circuit for performing such an operation.
25 shows an example of the internal configuration of 25. In the figure,
For example, the output of an image sensor 23 such as a CCD is output from an AF signal processing circuit 25.
After being amplified to a predetermined level by the preamplifier 251 in the above, a high-pass filter HPF252 (a band-pass filter may be used)
A predetermined high frequency component is extracted by the gate circuit 253.
Supplied to. The Kate circuit 253 is provided to form a window pulse from the vertical and horizontal synchronization signals output from the video signal processing circuit, and to extract only a video signal corresponding to a predetermined distance measurement area on the imaging surface of the imaging device 23. I have. Then, the high frequency component corresponding to the distance measurement region extracted by the gate circuit 253 is detected by the detection circuit 254, and then converted into a DC level according to the amount of the high frequency component by the integration circuit 255. This DC level is a signal that changes according to the degree of focusing, and is nothing but a focal voltage. This focus voltage is converted into a digital signal by the A / D converter 256 and supplied to the camera microcomputer 16. The microcomputer 16 stores the focus voltage in the memory, compares the newly input focus voltage level with the focus voltage previously input and stored in the memory in one field cycle, and reduces the difference. Command to drive the focusing lens in the direction, and adjust the focus voltage level that is input at the same time
Compared with Vr1 and Vr2, how much the current lens position deviates from the focal point, that is, the amount of blur is detected, and is used to determine the driving speed of the focusing lens 3 as described later. ing. In other words, the automatic focus detection system of the present invention is a control system that sequentially detects the above-described blur amount, reduces the speed when the blur amount is reduced, and stops at the focal point.

FIG. 3 shows an example of the contents determined as the driving contents of the lens group driving means for adjusting the focus on the lens side when the present invention is carried out. n is defined by 9 levels of numbers from 0 to 8, and each content is defined as defining the confusion circle expanding speed of ΔZn under the condition of opening the tele (telephoto) end. Therefore, basically, when there is an instruction of n from the camera side, the driving means moves at the speed of the enlargement speed ΔZn of the circle of confusion corresponding to the number (tele end / open). That is, for example, the speed of n = 1 is ΔZn = 0.
It is not necessary to be 32. At that time, even if the speed of n = 1 is the same, the speed of the arithmetic expression of ΔZn = ΔZn × (f / f _T ) ² × (F / F ₀ ) is obtained, which is small. Conversely, if n is the same, the rotation speed of the distance ring is the same for that lens regardless of the focal length f and the aperture value F. Therefore,
Of the lens specifications, the focal length f _T at the telephoto end and the open F-number F ₀
When a lens with a different distance comes, the value of ΔZn is constant, so that the rotation time required for, for example, ∞ to 1.2 m of the distance ring is different.

Figure 4 is an open F value _{1.4, f T = 100, f} T at close range 1.2m
= 1.2 mm for each lens of = 72 mm, f _T = 54 mm, showing the moving speed of the lens group for focus adjustment as a rough estimate of the required time. The shorter the focal length, the shorter the ∞-1.2m travel time and the faster the speed. This is a matter of course because the longer the focal length, the shallower the depth of field. Here, assuming that the speed is f = 54 mm and the speed of n = 8, the ∞-1.2 m moves in 0.6 sec, which is not general for a video camera lens. Therefore, the value of n marked with a circle on each lens, if f _T = 100 mm, n = 8, f
If n = 72 mm, n = 7, if f = 54 mm, n = 5 is the maximum value n _MAX
So that no higher speed can be achieved. How to handle n _MAX will be described with an example in the description of the flowchart below.

FIG. 5 shows how ΔZn fluctuates as the aperture is reduced while the telephoto end is fixed with a lens having an open F value of 1.4, for example. With respect to the aperture value F, the numerical value decreases with the first order ratio.

FIG. 6 shows an encoder for detecting the F value and the focal length f (mm).
Is an example in which numbers such as coefficients K _F and K _f are assigned to each region when 10 to 110 are divided into seven steps in a √2 series, and communication from the lens side to the camera side is performed. Then
The f (mm) and F values are not the values as they are, but may be transmitted as the values of the coefficients K _F and K _f .

FIG. 7 shows a duty ratio and a driving pattern when the variable speed of n = 1 to 8 is realized by, for example, duty control of a driving pulse of a lens driving pulse motor. In addition, as a method of changing the speed of the motor, voltage control or the like can be considered. When the motor has a rotation detecting means such as a pulse board, it is possible to perform fine adjustment of the rotation by applying feedback to the set duty ratio or voltage. Above, the coefficient K _F of Figure 6, the K _f, When K = K _F + K _f, for example, when you are taken with f = 54 mm, F2.8 _{is, K f = 3, K F} = 2 And K = 3 + 2 =
It becomes 5. Further, assuming that the value of K at the telephoto end and open state of each lens is Kt, this value is an immovable value unique to each lens, and can be stored in advance by the lens microcomputer. For example, f _T
Kt = 4 in the case of a lens having an F = 1.4 mm and an aperture value of F ₀ 1.4. For a lens with f _T = 72 mm and an open aperture of F ₀ 1.4,
Kt = 3. For a lens with f _t = 100 mm and an open aperture value of F ₀ 1.2, Kt = 2.

FIG. 8 shows that ΔK = K for a lens with f _T = 100 mm and an open aperture value of F ₀ 1.4 by a combination of each focal length and the aperture value.
It shows the value of -Kt. That is, Kt = 2 from the value of the lens at the telephoto end. For example, f = 54mm, F2.8
When photographing is performed at K, since K = 5, ΔK
= 5-2 = 3.

FIG. 10 shows the same value of ΔK for a lens with f _T = 54 mm and an open aperture value of F ₀ 1.4. As is apparent from the above description, the lens shown in FIG.
= 30mm, F5.6, ΔK = 5,
In the illustrated lens, ΔK = 3 for the same 30 mm and F5.6. In this manner, the value of ΔK differs for lenses having different focal lengths at the telephoto end and different aperture values F ₀ even when photographing at the same focal length and F value. Now, in this embodiment,
It is assumed that the AF device can determine small blur, medium blur, large blur, and focus as described above. Among these, the confusion circle expansion speed required for small blur and medium blur is 0.32 mm / sec for small blur and 0.45 mm / sec for medium blur in this AF device. FIG. 3 shows that the speed of the AF motor moves at n = 1 for small blur and n = 2 for medium blur during tele-opening. That is, when ΔK = 0, n is 1 for small blur and 2 for medium blur. Also, as shown in FIG. 5, when the aperture value F is opened in two steps from 1.4 to 2.8, the same 0.32 mm / sec
And 0.45 mm / sec, n = 3 for small blur and n = 4 for medium blur. At this time, ΔK = 1. Such ΔK
FIG. 9 shows the values of n for small blur and medium blur. The table for selecting n is constant regardless of the specifications of the lens.

In the embodiment described above, the focal length f
(Mm), detection of aperture value F, F value is × 2 series (1.4,2.8,
5.6, ... // two steps at a time), the focal length f Therefore, as shown in FIG. 9, for example, even if the value of n at the time of small blurring is a number such as 1, 3, 5, or 7, it is not limited to the values in these figures. . Depending on the design, a definition of a magnification different from that of the present embodiment can be made.

FIG. 11 is a flowchart for explaining the control operation of the camera microcomputer of the present invention. When starting in step 1, in steps 2 and 3,
The the lens unit as a data communication at the initial operation when mounted on the camera body, the outermost fastest degree n _MAX and Kt of the AF motor is read from the lens side to the camera side. As described above, n _MAX indicates the maximum speed that can be actually realized by the lens driving means among the speed Nos. n = 0 to 8. Step 4 and subsequent steps are, for example, a flow that is repeated in a cycle of 1/30 second in synchronization with the frame cycle. Step 4
In are loading the values of K _f and K _F from the lens. this is,
Loading focal length f (mm), the F value directly, in the camera-side microcomputer, may be converted into K _f and K _F. In step 5, it calculates the K = K _f + K _F. Conversely, the microcomputer on the lens side can perform this calculation and then read on by the microcomputer on the camera side. However, in this case, step 4 is omitted. In step 6, ΔK = K−Kt is calculated.
In Steps 7 to 9, in the case of focusing, out of focus, or out of focus, it is determined whether the blur is small, medium, or large. As a result, if focus is achieved, n = 0 (stop), and if the subject is largely out of focus, the maximum speed n _MAX is set to n. In the case of small blur and medium blur, an optimum value of n is set according to ΔK according to the conversion table of FIG. 9 (step 1).
0,15). In step 11, n set in steps 10 and 15
Is greater than or equal to the maximum speed n _MAX . n ≧ n _MAX
If you don't have that speed, step 16
, N = n _MAX . In this way, in each case n
In step 12, the information of n is transmitted from the camera side to the lens side.

The lens microcomputer drives the lens group for focus adjustment in accordance with the drive pattern shown in FIG. 7, for example, based on the n information.

In the above embodiment, the focal length f and the aperture value F are set to K _f , K _F
And the optimal speed No is selected. by the way,
To change the value of K by one, the focal length Alternatively, this is a case where the aperture value F changes by x2. So K _f ,
Even without conversion such as K _F From equation (2), 1, m can be calculated to make ΔK = m + 1. For example, f = 5 for a lens with f _T = 110 and F ₀ = 1.4.
When m = 6 and F = 5.6, m and 1 are given by
2,1 = 2 and ΔK = 4. Therefore, similar results can be obtained even if the system is constructed in this way.

(Effects of the Invention) As described above, in the AF system applied to the interchangeable lens camera, the predetermined movement of the focusing lens is defined as a common definition between the respective lenses regarding the driving speed of the lens group for focusing. Under the condition that the change of the circle of confusion with the amount is the maximum (in many cases, the tele end is open),
A driving speed is used such that the speed of change of the circle of confusion has a predetermined value. This speed is defined for a plurality of types. Under such a definition, the microcomputer on the camera side selects the optimum speed from the above-mentioned plurality of speeds based on the information on the blur of the subject and the information on the focal length f and the aperture value F. , The speed is determined, so the content of the calculation for the speed can be greatly reduced.In particular, the size of the microcomputer on the lens side can be greatly reduced, making it extremely practical as an AF system in an interchangeable lens system. Is big.

[Brief description of the drawings]

FIG. 1 is a block diagram of an embodiment of an automatic focusing apparatus of the present invention, FIG. 2 is a block diagram of an AF device suitable for implementing the present invention, and FIG. 3 is a diagram of an interchangeable lens of an embodiment of the present invention. FIG. 4 is a diagram for explaining the definition of the speed of the driving means, FIG. 4 is a diagram showing the time required for moving the lens having a different focal length at the telephoto end from ∞ to 1.2 m, and FIG. FIG. 6 is a diagram showing a relationship between n of each speed No and a confusion circle expansion speed. FIG. 6 shows conversion of K _f , K _{F applied} to each region when an aperture value F and a focal length f (mm) are detected in the region. FIG. 7 is a diagram showing a table, FIG. 7 is a diagram showing a duty ratio pattern when the speed is varied by duty control of a pulse motor, and FIG. 8 is a diagram when the focal length at the telephoto end is f _T = 100 mm and F1.4 is open. FIG. 9 is a diagram for explaining a value of ΔK based on a combination of a focal length and an F value. FIG. Shows a table, Fig. 10, the focal length and by a combination of F values, diagram for explaining the value of ΔK when the _{f T = 50mm, F 0 1.4} , the embodiment of FIG. 11 the present invention 4 is a flowchart for explaining the control operation of the camera-side microcomputer of the first embodiment.

Claims (4)

(57) [Claims] 1. A camera device in which a lens unit can be attached to and detached from a camera body, wherein: a focus detection means for detecting a focus state of a subject image formed by the lens unit; and a focus lens in the lens unit. A characteristic detecting unit that detects optical characteristic information relating to position sensitivity; and moving the focus lens in the lens unit to a focal point based on an output of the focus detecting unit and optical characteristic information of the characteristic detecting unit. Control means, wherein the control means obtains a confusion circle change speed accompanying the movement of the focus lens based on the optical characteristic information, and calculates a plurality of speed control information of the focus lens based on the confusion circle change speed. Wherein the focus lens is driven based on the speed control information. Dynamic focus adjustment device. 2. A camera device to which a lens unit is detachable, wherein: a focus detection means for detecting a focus state of a subject image formed by the lens unit; and a focus in the lens unit from the lens unit side. A characteristic detecting unit that detects optical characteristic information regarding the sensitivity of the position of the lens; and, based on an output of the focus detecting unit and optical characteristic information of the characteristic detecting unit, sets the focus lens in the lens unit to a focal point. Control means for calculating control information for movement and supplying the control information to the lens unit, wherein the control means obtains a confusion circle change speed accompanying the movement of the focus lens based on the optical characteristic information, A plurality of speed control information of the focus lens is defined based on the speed of change of the circle of confusion, and the focus control information is defined based on the speed control information. A camera device configured to drive an focusing lens. 3. A lens unit detachable from a camera unit, wherein: a characteristic output unit for outputting optical characteristic information relating to sensitivity of a position of a focus lens in the lens unit; and a subject imaged by the lens unit. Control means for moving the focus lens to a focal point based on control information calculated from the degree-of-focus information detecting the in-focus state of the image and the optical characteristic information output by the characteristic output means. Wherein the control information obtains a confusion circle change speed associated with the movement of the focus lens based on the optical characteristic information, and defines a plurality of speed control information of the focus lens based on the confusion circle change speed, A lens unit, which is information for driving the focus lens based on speed control information. 4. A camera system comprising a camera body and a lens unit detachable from the camera body, wherein focus detection means for detecting a focus state of a subject image formed by the lens unit; A characteristic detecting unit that detects optical characteristic information regarding the sensitivity of the position of the focus lens in the unit; and the focus lens in the lens unit based on the output of the focus detecting unit and the optical characteristic information of the characteristic detecting unit. Control means for moving to the focal point, wherein the control means obtains a speed of change of a circle of confusion associated with the movement of the focus lens based on the optical characteristic information, and determines a speed of change of the focus lens based on the speed of change of the circle of confusion. It is configured to define a plurality of speed control information and drive the focus lens based on the speed control information. A camera system.