JP2006235351A - Autofocus device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a hybrid type autofocus device capable of accurately performing focusing at high speed. <P>SOLUTION: A distance component calculation part 101 calculates a target distance on the basis of the range-finding data of a range-finding device 9 and further calculates a distance component. In the case of performing external light system autofocus, a focus lens driving amount is calculated by totaling a back focus component calculated on the basis of a back focus adjusting amount stored in a storage device 11 and the distance component. Then, the back focus adjusting amount is corrected so that the focus lens driving amount may coincide with the focus lens driving amount by contrast detection autofocus. The back focus adjusting amount stored in the storage device 11 is replaced with the corrected back focus adjusting amount. As a result, the lowering of the accuracy of the external light system autofocus caused by time change or the like is prevented. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to an autofocus device used for a photographing apparatus such as a camera.

  Conventionally, an electronic camera such as a digital still camera evaluates the sharpness of an image picked up by a photographing image sensor, and determines a state where the sharpness reaches a peak as a focused state. It has been known. When this method is adopted, there is no need to provide a separate focus detection sensor, which is advantageous for reducing the cost and size of the camera, but on the other hand, it takes the time to focus. Have.

  Therefore, in order to improve the speeding up of focusing, a hybrid autofocus including a contrast detection autofocus and an external light autofocus using a distance measuring device has been proposed (for example, see Patent Document 1). . In the hybrid autofocus, first, external light autofocus is performed, the focus lens is moved to the vicinity of the in-focus point, and then contrast detection autofocus is performed in the vicinity of the in-focus point, thereby achieving high-speed focusing.

  By the way, in the case of external light autofocus, since the subject distance obtained by the distance measuring device is converted into a focus lens drive amount and the focus lens is moved, the accuracy of focusing due to a change with time or a temperature change is prevented. For this purpose, it is necessary to correctly calibrate the relationship between the subject distance and the focus lens drive amount to be actually driven. Therefore, in the camera described in Patent Document 1 described above, the focusing result of the external light autofocus is corrected based on the focusing result according to the subject distance measured by the ranging device and the focusing result by contrast detection autofocus. Like to do.

JP 2003-107333 A

  However, since the conversion relationship of the focus lens drive amount with respect to the object distance is not a simple linear expression but a polynomial including a quadratic or higher term, a complicated calculation is required to obtain the correction coefficient, and the linear expression If the correction is simplified by such means, there is a drawback that the correction accuracy is lowered.

The first focus adjustment operation based on the subject distance measured by the distance measuring means and the second focus adjustment based on the focus evaluation value calculated from the image pickup signal of the image pickup device that picks up the subject. Storage means for storing a back focus adjustment amount obtained based on a focus lens driving amount of a photographing optical system when focused on a subject at a predetermined distance, and a distance measurement A drive amount calculating means for calculating a focus lens drive amount in the first focus adjustment operation based on the subject distance detected by the means and the back focus adjustment amount stored in the storage means; Compensation for correcting the back focus adjustment amount so that the focus lens drive amount matches the focus lens drive amount calculated by the drive amount calculation means. Characterized by comprising a means.
According to a second aspect of the present invention, in the autofocus device according to the first aspect, the back focus adjustment amount stored in the storage unit is replaced with the back focus adjustment amount corrected by the correction unit each time correction is performed by the correction unit. Means are provided.
According to a third aspect of the present invention, in the autofocus device according to the first or second aspect, the magnitude of the difference between the focus lens drive amount in the second autofocus and the focus lens drive amount calculated by the drive amount calculation means is small. When the predetermined amount is exceeded, the back focus adjustment amount is not corrected.
According to a fourth aspect of the present invention, in the autofocus device according to any one of the first to third aspects, selection means for selecting an operation mode for performing the focus adjustment operation of the photographing optical system only by the second focus adjustment operation, and selection And a control means for detecting the subject distance by the distance measuring means, calculating the focus lens drive amount by the drive amount calculating means, and correcting the back focus adjustment amount by the correcting means when the operation mode is selected by the means. Is.
According to a fifth aspect of the present invention, in the autofocus device according to any one of the first to fourth aspects of the present invention, the autofocus device further comprises a temperature detection means for detecting the device environment temperature, and the correction means corrects according to the temperature detected by the temperature detection means I tried to do it.
According to a sixth aspect of the present invention, in the autofocus device according to any one of the first to fifth aspects, the photographing optical system is a zoom lens having a variable focal length, and the correcting means is in accordance with the focal length of the photographing optical system. I corrected it.

  According to the present invention, the back focus adjustment amount is corrected so that the focus lens drive amount in the second autofocus based on the focus evaluation value matches the focus lens drive amount calculated in the first autofocus. Therefore, the focus lens drive amount in the first autofocus can be calculated with high accuracy.

  Hereinafter, the best mode for carrying out the present invention will be described with reference to the drawings. FIG. 1 shows an embodiment of the present invention, and is a block diagram of a digital still camera equipped with an autofocus device. In the block diagram of FIG. 1, only components related to the invention are shown. The photographing lens 2 provided in the camera includes a zoom lens 22 having a variable focal length and a focus lens 21 for performing focus adjustment.

  The zoom lens 22 is driven in the optical axis direction by the zoom lens driving device 3. The position of the zoom lens 22 in the optical axis direction is detected by the zoom lens position detection device 4. The focus lens 21 is driven in the optical axis direction by the focus lens driving device 5, and the position of the focus lens 21 in the optical axis direction is detected by the focus lens position detection device 6. A subject image is formed by the photographing lens 2 on the imaging surface of the imaging device 7, but the focused subject image is formed on the imaging surface by driving the focus lens 21 and performing focus adjustment. . A CCD image pickup device, a MOS type image pickup device, or the like is used for the image pickup device 7, and an image signal output from the image pickup device 7 is input to the control device 1 and converted there to image data.

  The digital still camera of this embodiment includes both a contrast detection autofocus with high focusing accuracy and an external light autofocus with a fast focusing operation. Then, by operating the shooting mode selection switch 13, (a) a contrast AF control mode using only contrast detection autofocus, (b) an external light AF control mode using only external light autofocus, (c) ) One of the hybrid AF control modes using both the contrast detection autofocus and the external light autofocus can be selected.

  The contrast evaluation value calculation unit 100 of the control device 1 extracts a predetermined high frequency component from the spatial frequency of the image data in the AF area, and calculates the contrast evaluation value by integrating the absolute values of the extracted high frequency components. . In contrast detection autofocus, focusing is performed by driving the focus lens 21 to a focus lens position where the contrast evaluation value reaches a peak. Reference numeral 12 denotes a half-push switch that is turned on by half-pressing a release button (not shown). When the half-push switch 12 is turned on, an AF operation is started.

  The distance measuring device 9 is an external light AF type distance measuring device that performs known passive distance measurement and active distance measurement. The distance measuring device 9 receives subject light through the light receiving lens 8 according to a command from the control device 1 and corresponds to the distance to the subject. Ranging data is output to the control device 1. The distance component calculation unit 101 of the control device 1 calculates a subject distance based on the acquired distance measurement data, and further converts the calculated subject distance into a driving amount of the focus lens 21. Reference numeral 10 denotes a temperature detection device that detects the temperature inside the camera. The camera control program, adjustment values necessary for camera control, and the like are stored in the storage device 11.

<< Explanation of correction for back focus component >>
In the external light autofocus, first, the subject distance calculated based on the distance measurement data of the distance measuring device 9 is converted into a driving amount DA of the focus lens 21 (hereinafter, this driving amount is referred to as a distance component) by a predetermined conversion formula. Call). This distance component is the driving amount from the lens position where the object at infinity is in focus, and the feed amount DT which is the driving amount from the reference lens position of the focus lens 21 is the position where the object at infinity is in focus. The feed amount DB (hereinafter referred to as the back focus component) and the distance component DA are totaled.

  The back focus component varies from camera to camera due to component dimensional errors and assembly errors. Therefore, adjustment is performed for each camera in the inspection adjustment process at the time of camera shipment. For example, the focal length of the photographic lens 2 is set to the minimum fmin, the focus lens 21 is driven to a position where a subject at a predetermined distance (for example, infinity) is in focus, and the driving amount DB (fmin at that time) , T0) is stored in the storage device 11 as the initial value of the back focus adjustment amount. T0 is the temperature at the time of inspection. This back focus adjustment amount corresponds to the back focus component DB in the camera state (focal length fmin, temperature T0) at the time of inspection.

  Note that the back focus adjustment amount DB (fmin, T0) is a value in the case of the focal length fmin, and this value changes according to the focal length f of the photographing lens 2. Therefore, the value DB (f, T) for each focal length may be calculated based on the value DB (fmin, T0) actually measured by the inspection, and stored as a table, or the value DB (fmin, T0). And a correction coefficient α (f) related to the focal length may be stored. In that case, DB (f, T0) is represented by their product DB (fmin, T0) · α (f). Hereinafter, a case where the correction coefficient α (f) is used will be described as an example.

Further, since the back focus adjustment amount DB (fmin, T0) changes depending on the temperature T of the camera, the temperature correction coefficient β (ΔT) based on the temperature T0 is stored in advance in the storage device 11 together with the temperature T0. deep. However, ΔT = T−T0. That is, in the camera at the time of shipment, the back focus component DB at the focal length f and the temperature T is expressed by the following equation (1) using the back focus adjustment amount DB (fmin, T0). When the inspection conditions are f = fmin and T = T0, α (fmin) = 1 and β (ΔT = 0) = 1, and DB = DB (fmin, T0) as described above.
DB = DB (fmin, T0) · α (f) · β (ΔT) (1)

  By the way, the back focus component DB changes not only with the camera temperature T but also with the temporal change in the positional relationship between components. Therefore, in this embodiment, the back focus adjustment amount DB (fmin, T0) is set so that the focus lens extension amount calculated by the external light autofocus and the focus lens extension amount when autofocusing is performed by contrast detection match. ) Was corrected.

When the corrected back focus adjustment amount is expressed as DBC (fmin, T0), the back focus adjustment amount DB (fmin, T0) stored in the storage device 11 in advance is corrected to the back focus adjustment amount DBC (fmin, T0). ). Then, from the next external light autofocus, the back focus component DB is calculated by Expression (1) ′ using the corrected back focus adjustment amount DBC (fmin, T0) instead of Expression (1). After correction, the feed amount DT of the focus lens 21 is calculated by the following equation (2).
DB = DBC (fmin, T0) · α (f) · β (ΔT) (1) ′
DT = DA + DBC (fmin, T0) · α (fmin) · β (ΔT) (2)

  When the back focus adjustment amount is stored as a table for each focal length without using the correction coefficient α (f), the back focus adjustment amount DB (corresponding to a plurality of focal lengths f1, f2, f3,... f1, T0), DB (f2, T0), DB (f3, T0),... are stored in the storage device 11. If DT and DT0 are acquired at the focal length f1, the back focus adjustment amount DB (f1, T0) related to the focal length f1 is corrected to DBC (f1, T0) based on them.

  FIG. 2 is a flowchart showing a series of processes of the AF operation by half-pressing the release button. The above-described back focus component correction is performed during the AF operation. When the release button is half-pressed while the camera is turned on, the half-press switch 12 in FIG. 1 is turned on, and the half-press process in FIG. 2 is started. In step S201, it is determined whether or not the above-described contrast AF control mode is selected by the shooting mode selection switch 13. If it is determined in step S201 that the contrast AF control mode is selected, the process proceeds to step S300 in FIG. 3, and if it is determined that the contrast AF control mode is not selected, the process proceeds to step S202.

  In step S202, it is determined whether the external light AF control mode is selected by the shooting mode selection switch 13. If it is determined in step S202 that the external light AF control mode is selected, the process proceeds to step S400 in FIG. 4, and if it is determined that it is not selected, that is, if the hybrid AF control mode is selected. Proceed to step S500 in FIG.

(When contrast AF control mode is selected)
When the process proceeds to step S300 in FIG. 3, a ranging process is executed in step S300. That is, the control device 1 acquires distance measurement data based on subject light received through the light receiving lens 8 from the distance measurement device 9. Then, the distance component calculation unit 101 calculates the subject distance based on the distance measurement data. In step S301, it is determined whether the subject distance has been obtained by the distance measuring process in step S300. If it is determined in step S301 that the subject distance has not been obtained, the process proceeds to step S308, and the focus lens 21 is driven to a position where the contrast evaluation value reaches a peak by well-known contrast detection autofocus to perform focusing. End the half-press process. In this case, since the subject distance is not acquired, the back focus adjustment amount correction process described later is not performed.

  On the other hand, if it is determined in step S301 that the subject distance has been obtained, the process proceeds to step S302. In step S302, the distance component calculation unit 101 converts the subject distance into the driving amount of the focus lens 21 to calculate the distance component DA. In step S303, based on the focal length f of the photographing lens 2, the temperature T detected by the temperature detection device 10, and the back focus adjustment amount stored in the storage device 11, the equation (1) or the equation (1 ) ′ To calculate the back focus component DB. Here, when the initial value DB (fmin, T0) is stored as the back focus adjustment amount, Expression (1) is used, and a corrected value DBC (fmin, T0), which will be described later, is stored as the back focus adjustment amount. If this is the case, equation (1) ′ is used.

  In step S304, the distance component DA obtained in step S02 and the back focus component DB obtained in step S303 are summed to calculate a focus lens extension amount DT which is a total driving amount of the focus lens 21. In the subsequent step S305, the focus lens 21 is driven to a position where the contrast evaluation value reaches a peak by well-known contrast detection autofocus, and focusing is performed.

  In step S306, a difference ΔDT = DT−DT0 between the focus lens extension amount DT0 and the focus lens extension amount DT calculated in step S304 in the contrast detection autofocus performed in step S305 is obtained, and the magnitude | ΔDT | It is determined whether or not it is equal to or less than a predetermined value a. This process determines whether or not the focus lens extension amount DT calculated by the external light autofocus is reliable. If “| ΔDT |> a” is determined, it is determined that the focus lens feed amount DT calculated in step S304 is not reliable, and step S307 for correcting the back focus adjustment amount is skipped. A series of half-press processes is terminated.

  On the other hand, if “| ΔDT | ≦ a” is determined in step S306, it is determined that the focus lens feed amount DT calculated in step S304 is reliable, so the process proceeds to step S307 to adjust the back focus. Amount correction processing is performed. Here, a case where the back focus adjustment amount correction process is performed for the first time after camera shipment, that is, a case where DB (fmin, T0) is stored as the back focus adjustment amount in the storage device 11 will be described.

  In step S307, (a) the focus lens extension amount DT0 when the focus is actually in focus in the contrast detection autofocus in step S305, and (b) the focus lens extension amount DT calculated by the external light autofocus in step S304. And (c) The back focus adjustment amount DB (fmin, T0) is corrected based on the difference ΔT = T−T0 between the temperature T during the half-pressing process and the above-described inspection temperature T0.

Although DT is calculated by the following equation (3), it may deviate from the actual focus lens feed amount DT0 due to, for example, a change over time. Therefore, the back focus adjustment amount DB (fmin, T0) is corrected so that the calculated value DT by the external light formula is equal to the actually measured value DT0. The corrected back focus adjustment amount is DBC (fmin, T0). That is, the corrected back focus adjustment amount DBC (fmin, T0) is set so as to satisfy the following equation (4). Therefore, the corrected back focus adjustment amount DBC (fmin, T0) is calculated by the following equation (5).
DT = DA + DB (fmin, T0) · α (f) · β (ΔT) (3)
DT0 = DA + DBC (fmin, T0) · α (f) · β (ΔT) (4)
DBC (fmin, T0) = (DT0−DA) / {α (f) · β (ΔT)} (5)

  The back focus adjustment amount DB (fmin, To) stored in the storage device 11 is replaced with the calculated corrected back focus adjustment amount DBC (fmin, To), and the series of half-press processes ends. Next, half-press processing is performed, and when the back focus component DB is calculated in step S303, the corrected back focus adjustment amount DBC (fmin, To) stored in the storage device 11 and the above-described formula (1) ) 'And the operation is performed.

In the above-described example, the back focus adjustment amount DB (fmin, T0) is corrected to DBC (fmin, T0). However, instead of correcting the back focus adjustment amount DB (fmin, T0) itself, a correction coefficient h is introduced. You may do it. That is, the correction coefficient h is calculated by the following equation (6), and the corrected back focus adjustment amount is DB (fmin, T0) · h. The correction coefficient h is stored in the storage device 11. In this case, the stored back focus adjustment amount DB (fmin, T0) is not rewritten, and only the correction coefficient h is rewritten every time correction is performed.
h = (DT0−DA) / {DB (fmin, T0) · α (f) · β (ΔT)} (6)

  In FIG. 3, the processing from step S300 to step S304 related to the calculation of the focus lens extension amount DT by external light autofocus and the contrast detection autofocus processing in step S305 are described as synchronization processing. Asynchronous processing is also acceptable. That is, the contrast detection autofocus itself does not have to wait for a series of processes related to distance measurement to end, and it is sufficient that both pieces of information DT and DT0 are prepared before the process of step S307.

(When external light AF control mode is selected)
Next, a case will be described in which it is determined in step S202 in FIG. 2 that the external light AF control mode is selected and the process proceeds to step S400 in FIG. In step S400, a distance measurement process similar to that in step S300 in FIG. 3 is executed, and the subject distance is calculated based on the distance measurement data. In step S401, it is determined whether or not the subject distance has been obtained by the distance measuring process in step S400. If the subject distance is obtained, the process proceeds to step S402. If the subject distance cannot be obtained, the process proceeds to step S406. move on.

  When the process proceeds from step S401 to step S406, since the subject distance cannot be obtained and focusing cannot be performed by the external light AF, focusing is performed by contrast detection autofocus even in the external light AF control mode. Then, a series of half-press processes are completed.

  On the other hand, when the process proceeds from step S401 to step S402, the same processes as those in steps S302, S303, and S304 in FIG. 3 are executed in order in steps S402 to S404. That is, the subject distance is converted into the distance component DA in step S402, the back focus component DB is calculated by equation (1) ′ or equation (1) in step S403, and the focus lens extension amount DT = DA + DB is calculated in step S404. .

  In step S405, the focus lens driving device 5 is controlled based on the focus lens feed amount DT calculated in step 404, focusing by external light autofocus is performed, and the series of half-press processes is terminated. As described above, in the external light AF control mode, only one of the calculation of the focus lens extension amount DT based on the distance measurement or the lens driving by contrast detection autofocus is performed. The focus adjustment amount is not corrected.

(When hybrid AF control mode is selected)
The case where the external light AF control mode is not selected in step S202 of FIG. 2, that is, the case where it is determined that the hybrid AF control mode is selected and the process proceeds to step S500 of FIG. 45 will be described. In step S500, a distance measurement process similar to that in step S300 in FIG. 3 is executed, and the subject distance is calculated based on the distance measurement data. In step S501, it is determined whether or not the subject distance has been obtained by the distance measuring process in step S500. If the subject distance is obtained, the process proceeds to step S502. If the subject distance cannot be obtained, the process proceeds to step S509. move on.

  When the process proceeds from step S501 to step S509, the subject distance cannot be obtained, and focusing cannot be performed by the external light AF, and focusing is performed by contrast detection autofocus. Then, a series of half-press processes are completed.

  On the other hand, when the process proceeds from step S501 to step S502, the same processes as those in steps S402, S403, S404, and S405 in FIG. 4 are sequentially executed in steps S502 to S505. That is, the subject distance is converted into the distance component DA in step S502, the back focus component DB is calculated by equation (1) ′ or equation (1) in step S503, and the focus lens feed amount DT = DA + DB is calculated in step S504. . In step S505, the focus lens driving device 5 is controlled based on the focus lens feed amount DT calculated in step 504, and focusing by external light autofocus is performed.

  In step S506, focusing is performed by contrast detection autofocus. Thus, in the hybrid AF control mode, the focus lens 21 is first moved to the vicinity of the focus position by external light autofocus, and the scan range is limited to a narrow range including the moved lens position. Contrast detection autofocus is used. As a result, high-precision focusing can be performed at higher speed.

  As described above, in this embodiment, the back focus adjustment amount DBC (fmin, T0) is corrected every time DT0 and DT are calculated, so that even when the camera changes with time, accuracy is not reduced. Contrast detection autofocus can be performed. Therefore, the scan range in step S506 can be set narrower than in the case of the conventional hybrid AF, and the hybrid AF operation can be made faster.

  In subsequent steps S507 and S508, processing similar to that in corresponding steps S306 and S307 in FIG. 3 is performed. That is, in step S507, it is determined whether the magnitude | ΔDT | of the difference between the focus lens extension amount DT0 in step S506 and the focus lens extension amount DT calculated in step S504 is equal to or less than a predetermined value a. If it is determined that “| ΔDT |> a”, it is determined that the calculated focus lens extension amount DT is not reliable, and step S508 for correcting the back focus adjustment amount is skipped. End the half-press process.

  On the other hand, if “| ΔDT | ≦ a” is determined in step S507, it is determined that the calculated focus lens extension amount DT is reliable, and the process proceeds to step S508 to perform back focus adjustment amount correction processing. Do. The correction process is the same as that in step S307 described above, and a description thereof is omitted here. If the corrected back focus adjustment amount DBC (fmin, T0) is calculated, the new back focus adjustment amount DBC (fmin) calculated from the back focus adjustment amount DB (fmin, To) stored in the storage device 11 is calculated. , To), and the series of half-press processes is completed.

The above-described embodiment can provide the following effects.
(A) The back focus adjustment amount is corrected every time the focus lens drive amount DT by the external light autofocus and the focus lens drive amount DT0 by the contrast detection autofocus are acquired. It is possible to prevent a decrease in accuracy of the external light autofocus.
(B) Since the distance measurement is performed in parallel even in the contrast AF control mode, the correction frequency of the back focus adjustment amount increases, and the back focus adjustment amount of the storage device 11 deviates greatly from the appropriate value. Can be prevented.
(C) In the case of “| ΔDT |> a”, since the back focus adjustment amount is not corrected, it is possible to prevent inappropriate correction from occurring.

  As described above, the present invention can be applied to various types of focus devices as long as the focus device includes autofocus by distance measurement and autofocus that can actually obtain the focus lens driving amount, such as contrast detection autofocus. Can be applied.

  In the correspondence between the embodiment described above and the elements of the claims, the distance measuring device 9 and the distance component calculation unit 101 use the distance measuring unit, the external light autofocus uses the first focus adjustment operation, and the contrast detection. Auto-focusing constitutes the second focus adjustment operation, the control device 1 constitutes drive amount calculation means, correction means, replacement means and control means, and the shooting mode selection switch 13 constitutes selection means. The above description is merely an example, and when interpreting the invention, there is no limitation or restriction on the correspondence between the items described in the above embodiment and the items described in the claims.

1 is a block diagram of a digital still camera equipped with an autofocus device according to an embodiment of the present invention. It is a figure which shows a part of flowchart explaining the AF operation | movement by half-pressing a release button. It is a flowchart which shows a series of processes at the time of selecting contrast AF control mode. It is a flowchart which shows a series of processes at the time of selecting external light type AF control mode. It is a flowchart which shows a series of processes at the time of selecting hybrid AF control mode.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Control apparatus 2 Shooting lens 3 Zoom lens drive device 4 Zoom lens position detection apparatus 5 Focus lens drive apparatus 6 Focus lens position detection apparatus 7 Imaging device 8 Light receiving lens 9 Distance measuring device 10 Temperature detection device 11 Storage device 12 Half-press switch 13 Shooting mode selection switch 21 Focus lens 22 Zoom lens 100 Contrast evaluation value calculation unit 101 Distance component calculation unit

Claims (6)

The first focus adjustment operation based on the subject distance measured by the distance measuring means and the second focus adjustment operation based on the focus evaluation value calculated from the imaging signal of the image sensor that images the subject can be performed. In autofocus device,
Storage means for storing a back focus adjustment amount obtained based on a focus lens drive amount of the photographing optical system when focusing on a subject at a predetermined distance;
A drive amount calculating means for calculating a focus lens drive amount in the first focus adjustment operation based on the subject distance detected by the distance measuring means and the back focus adjustment amount stored in the storage means;
And a correction unit that corrects the back focus adjustment amount so that the focus lens drive amount during the second focus adjustment operation matches the focus lens drive amount calculated by the drive amount calculation unit. Autofocus device. The autofocus device according to claim 1,
An autofocus device comprising a replacement unit that replaces the back focus adjustment amount stored in the storage unit with the back focus adjustment amount corrected by the correction unit each time correction is performed by the correction unit. The autofocus device according to claim 1 or 2,
The correction unit is configured to adjust the back focus adjustment amount when the magnitude of the difference between the focus lens drive amount in the second autofocus and the focus lens drive amount calculated by the drive amount calculation unit exceeds a predetermined amount. The autofocus device is characterized in that no correction is performed. In the autofocus device according to any one of claims 1 to 3,
Selection means for selecting an operation mode for performing the focus adjustment operation of the photographing optical system only by the second focus adjustment operation;
When the operation mode is selected by the selection unit, the distance measurement unit detects the subject distance, the drive amount calculation unit calculates the focus lens drive amount, and the correction unit corrects the back focus adjustment amount. And an autofocus device characterized by comprising control means. In the autofocus device according to any one of claims 1 to 4,
Equipped with temperature detection means for detecting the device ambient temperature,
The auto-focus device according to claim 1, wherein the correction means corrects the temperature according to the temperature detected by the temperature detection means. In the autofocus device according to any one of claims 1 to 5,
The photographing optical system is a zoom lens having a variable focal length,
The auto-focus device according to claim 1, wherein the correction unit corrects the correction according to a focal length of the photographing optical system.

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