WO2008114888A1 - Focal point adjusting method and focal point adjusting device in imaging apparatus - Google Patents

Abstract

First and second test charts (CH1, CH2) each having an imaging pattern defined by white color and black color are set in front and rear of the target position (P) of an object, a focus lens (3) is moved in the direction of optical axis X, focal point evaluation value of the imaging pattern focused on an image element (5) is determined for each of the first and second test charts (CH1, CH2) in correspondence with the movement quantity of the focus lens (3), and the position of the focus lens (3) is set such that the focal point evaluation value in the first test chart (CH1) coincides with the focal point evaluation value in the second test chart (CH2).

Description

 Description Focus adjustment method and focus adjustment apparatus for imaging apparatus TECHNICAL FIELD

 The present invention relates to a focus adjustment method and a focus adjustment apparatus for setting an imaging lens at a focus position using an image signal obtained through an imaging element such as a CCD in an imaging apparatus. Background art

 Conventionally, as shown in FIG. 1 (a), the contrast of the image projection light to be picked up is detected by the image pickup device 20 1 such as a camera, and the contrast is detected. A focus adjustment method using a hill-climbing method is known in which the imaging optical system is moved so as to maximize the focus adjustment.

 The imaging device 20 1 guides the subject 20 3 image to an imaging device 20 4 such as a CCD through an imaging lens 2 0 2 and converts it into an electrical signal, and the focus detection unit 2 5 5 It is configured to detect the last.

 As shown in Fig. 1 (b), the hill-climbing focus adjustment method is such that the imaging optical system such as the imaging lens 20 2 and the imaging device 2 0 4 is at the in-focus position with respect to the subject 2 0 3. In this case, the image of the subject 20 3 becomes the maximum contrast, and the contrast is reduced when defocusing occurs, so the image is taken to aim for the top of the contrast characteristics. This is to adjust the position of lens 2 0 2.

In addition, when adjusting the focus, a method is known in which the focus is adjusted by measuring the MTF (Modulation 1 Transfer Function) of the captured subject image. For details, see M There is a focus adjustment method that measures the change in TF and sets the position of the imaging lens so that the MTF of a predetermined spatial frequency is maximized (see, for example, Patent Documents 1 and 2).

 Patent Document 1: Japanese Patent Application Laid-Open No. 6 2-2 8 4 3 14

 Patent Document 2: Japanese Patent Laid-Open No. 2 0 0 5 — 2 5 8 3 60 Disclosure of Invention

 However, according to the conventional focus adjustment method for obtaining the maximum value of the contrast and the maximum value of MTF by the hill-climbing method, generally, the imaging lens is reciprocated to both sides via the focusing position in the optical axis direction. Therefore, it is necessary to detect the best contrast position, which may impair the workability for focus adjustment (in other words, compared with the method of adjusting by moving the imaging lens in one direction). This may impair workability). In addition, if the contrast characteristics and MTF characteristics with respect to the defocus amount are almost flat near the peak point and the peak point does not appear clearly, the focus position of the imaging lens can be adjusted accurately. There was also a risk that it would be difficult to do.

rr 価値のピ ―ク点が不明瞭であつても精度よく合焦位置 を調整できる と と もに、 その 整を容易にできる焦点 整方法を提供す ることを目的とする In view of this, the present invention relates to the contrast 卜 characteristics and MTF characteristics obtained when the focusing position is adjusted by moving the fe image lens in the optical axis direction in the imaging apparatus.

rr The purpose is to provide a focusing method that can adjust the in-focus position with precision even if the peak point of the value is unclear, and that can be easily adjusted.

 The invention described in claim 1 made to achieve this object

 , ·

The image sensor that guides the subject image to the image sensor <the imaging lens and the optical image of the subject image guided through the self-image lens and outputs an image signal

 ,

And the imaging lens is moved along an optical axis connecting the subject and the δ self-image element, and is guided to the front image element. ■ / one

A point adjustment method for focusing on the subject image.

First and second test charts having an imaging pattern defined in white and black are set back and forth through the target position of the subject, and the imaging lens is set in the optical axis direction. For each of the first and second testers, the focus evaluation value of the imaging pattern imaged on the imaging element is obtained in association with the amount of movement of the imaging lens. The position of the imaging lens is set so that the focus evaluation value in the first test chart matches the saddle point evaluation value in the second test chart. .

 According to Λ¾ and the adjustment method in the imaging device according to the first aspect of the present invention, the imaging method is provided with an imaging pattern defined in white and black after passing through the target position of the subject on the optical axis. First and second test charts are set, the imaging lens is moved in the optical axis direction, and each of the first and second test charts is associated with the amount of movement of the image lens. Determine the focus evaluation value of the imaging model imaged in the image, and set the position of the imaging lens so that the focus evaluation value in the first test chart matches the focus evaluation value in the second test chart. Therefore, even when the peak point of the focus evaluation value of the subject image captured through the imaging lens is unclear, the accuracy <the in-focus position can be adjusted and the adjustment can be facilitated.

 In other words, the imaging lens is moved along the optical axis, and the focus evaluation value of the first test chart and the second test chart are set to match the position of the imaging lens when the evaluation value matches. Since the focus position is sufficient, the focus position can be obtained with higher accuracy than the conventional hill climbing method, and the adjustment time can be shortened.

 Further, the focus adjustment method in the imaging device according to claim 1 is an orthogonal line orthogonal to the optical axis as in the invention according to claim 2.

A pair of the first test chart and the first test chart. The first and second test charts that are spaced along the optical axis can be placed at the same time by placing them in positions that do not overlap each other. Imaging is possible, focus adjustment is easy, and the focusing position of the imaging lens can be detected with high accuracy.

 In addition, the focus adjustment method in the imaging apparatus according to claim 1 or 2, wherein the focus evaluation value is an edge portion of the imaging pattern as in the invention according to claim 3. By using this index to represent the amount of spatial frequency components, the focus evaluation value can be obtained more easily than obtaining the focus evaluation value for the entire surface. In other words, when the imaging pattern is focused on the image sensor and imaged, the edges appear clearly and the high frequency component of the spatial frequency becomes strong.

If the in-focus position with respect to the image sensor is shifted, the edge appears blurred and the high frequency component of the spatial frequency is weak, so the edge image is detected, and the detected edge image is differentiated and converted to a point image. This point image can be Fourier transformed to find the MTF of the optical system.

 The focus adjustment method in the imaging apparatus according to claim 1 is the same as the invention according to claim 4, wherein the first test chart and the second test chart include the imaging By arranging a plurality of patterns in parallel, the influence of noise can be reduced and a focus evaluation value can be obtained with higher accuracy than when there is a single captured pattern. In other words, if there are multiple imaging patterns, the focus evaluation values obtained from the respective imaging patterns are compared, and if there is variation due to noise, the imaging pattern on which noise is superimposed is removed to evaluate the focus of the appropriate imaging pattern. A value can be selected. In addition, by placing multiple image pickup patterns at the center of the image or at a position away from the center, the focal position in the image can be set according to the application, improving added value.

Next, an invention according to claim 5 is directed to an imaging lens that guides a subject image to an imaging device, and a photoelectric conversion of the subject image guided through the imaging lens. An image sensor that outputs image signals of a plurality of colors, a focus evaluation value detection unit that detects a focus evaluation value of the subject image formed on the image sensor in association with a movement amount of the imaging lens, A focusing device in an imaging device, wherein the BiJ S self-lens is set at a predetermined position based on a detection result detected by the focus evaluation value detection means, and the light Along the axis

The first and second textures having an image pattern defined in white and black are set after passing through the target position of the subject, and the focus evaluation value detecting means For each of the first and second test pieces, the image pickup pattern imaged on the HU image pickup device is associated with the amount of movement of the image pickup lens.

^ p¾ * has a value, and the position of the imaging lens is set so that the respective focus evaluation values of the first and first test charts match.

According to the focus adjustment device in the imaging device according to the fifth aspect of the invention, in the same manner as the invention according to the first aspect of the invention, along the optical axis, and back and forth through the target position of the subject, Set the first and second test charts that have an imaging pattern defined in white and black, and the imaging pattern that is imaged on the imaging device according to the amount of movement of the imaging lens The position of the imaging lens is set so that the focus evaluation value in the first test chart matches the focus evaluation value in the second test chart. Even if the peak point of the saddle point evaluation value of the subject image picked up through is unclear, the in-focus position can be adjusted accurately and the adjustment can be made easily. In addition, the focus adjustment device in the imaging device according to claim 5 is the same as the invention according to claim 6, wherein the first and second test charts are arranged on the optical axis. In addition to being configured symmetrically through orthogonal lines orthogonal to each other, they are configured so that they do not overlap with each other. Similarly, the first spaced apart along the optical axis The first test chart and the second test chart can be imaged simultaneously, focus adjustment is easy, and the in-focus position of the imaging lens can be detected with high accuracy.

 In addition, the focus adjustment device in the imaging device according to claim 5 or 6 is characterized in that, as in the invention according to claim 7, the focus evaluation value is an edge portion of the imaging pattern. In the same way as the invention described in claim 3, it is possible to obtain a focus evaluation value more easily than obtaining a focus evaluation value for the entire surface. it can.

 According to the focus adjustment method and the focus adjustment apparatus in the imaging apparatus of the present invention, the first and the imaging pattern defined in white and black on the optical axis are defined in front and back through the target position of the subject. Set the second test chart, move the imaging lens in the optical axis direction, and form an image on the image element in association with the movement amount of the imaging lens for each of the first and second test charts. Find the focus evaluation value of the captured image and set the position of the imaging lens so that the focus evaluation value in the first test and the focus evaluation value in the second test match. Therefore, even if the vicinity of the peak point of the focus evaluation value of the subject image captured through the imaging lens is unclear, it is possible to adjust the focus position with ease and to make the adjustment easily.

 Further, according to the focus adjustment method and the focus adjustment device in the imaging apparatus of the present invention, the first test chart and the second test chart that are separated along the optical axis can be imaged at the same time. The workability for adjustment is good, and the in-focus position of the imaging lens can be detected with high accuracy. Brief Description of Drawings

 FIG. 1 is an explanatory diagram of a conventional focus adjustment method.

FIG. 2 is a schematic diagram showing a focus adjustment method in an imaging apparatus according to an embodiment of the present invention. (A) FIG. 2 shows an installation example of the first and second testers に. (B) The MTF characteristics detected in the figure are shown.

 FIG. 3 is a block diagram showing the configuration of the image pickup apparatus in the embodiment. FIG. 4 is a diagram showing a method for measuring MTF in the embodiment.

 FIG. 5 is a flowchart showing the procedure of the focus adjustment method in the same embodiment.

 Fig. 6 shows a modified example of the test jar shown in Fig. 2 (a). BEST MODE FOR CARRYING OUT THE INVENTION

 Next, an embodiment of the focus adjustment method and the focus adjustment apparatus in the imaging apparatus of the present invention will be described with reference to the drawings.

 Fig. 2 is a schematic diagram showing the focus adjustment method divided into the image pickup apparatus of the present embodiment. (A) Fig. 2 shows an example of the BX arrangement for the first and second textures h, and (b) Fig. Fig. 3 is a block diagram showing the configuration of the imaging device in the example, and Fig. 4 is the example in the example.

Fig. 5 is a diagram showing the MTF measurement method, Fig. 5 is a flowchart showing the focus adjustment procedure in this example, and Fig. 6 is an excavation showing a variation of the test chart in Fig. 2 (a). is there.

 As shown in FIG. 2 (a), the focus adjustment method in the image pickup apparatus of the present embodiment is a force-force lens (so-called this book) configured to be movable in the optical axis X direction on the image pickup apparatus 1. 3) and an image sensor 5 that optically converts the subject image guided through the focus lens 3 and outputs an image signal, and covers the subject P and the image sensor 5. Along the optical axis X

The first test subject C H 1 and the second test subject with the fe pattern that are defined in white and color before and after the target position of the subject P

Set CH 2 and move the focus lens 3 along the optical axis X. Adjust the position of the focus lens 3 via the adjustment device 2 1 so that the subject P image focused on the image sensor 5 is in focus.

 In Fig. 2 (a), M is the distance from the force lens 3 to the subject P, N is the distance from the focus lens 3 to the first test chart CH 1, and F is the first lens from the focus lens 3. Distance to test CH2, the first test-CH1 and the second test chart C

H 2 is arranged at substantially the same distance from the target position of the subject P. For the positions of the first test-CH 1 and the second test CH 2, MTF is calculated in advance from optical information such as the focal length and F value of the force lens 3, respectively. The calculated MTF may be determined to be equal, or may be determined experimentally using a tuned lens.

 For details, as shown in Fig. 2 (b), move the force lens 3 in the direction of the optical axis X, and the first test-h C H 1 and the second test chart

For each of C H 2, the image sensor is associated with the amount of movement of the focus lens 3.

Find the focus evaluation value of the imaged pattern imaged in Fig. 5 and use the first test chart.

The position of the focus lens 3 is set so that the focus evaluation value at C H 1 matches the focus evaluation value at the first test.

Next, as shown in FIG. 3, the imaging device 1 includes a front lens 2, a focus lens 3, a filter that removes harmful infrared rays and harmful reflected light (infrared removal filters and optical filters). 4) Image sensor (CCD: Charge Coupled Devices) 5, Image sensor 5 forces AFE (Analog Front Front) that converts the output analog image signal to digital image signal C and outputs it E nd) 6, Image sensor 5 and AFE 6 are controlled in a predetermined cycle TG (Timing Generator) 1 3 、 Focus lens 3 is driven to slide in the optical axis direction A focus detection unit 10 and the like for detecting the slide amount of the focus lens 3 through the slide drive unit 12 and the sensor 11 1 are provided.

 The imaging element 5 is configured by arranging a plurality of photoelectric conversion elements in parallel, and is configured to photoelectrically convert the imaging signal S for each photoelectric conversion element and output an analog image signal.

 AFE 6 is a correlated double sampling circuit (CDS) 7 that removes noise from analog image signals output via image sensor 5, and a correlated double sampling circuit 7 The analog image signal from the image sensor 5 input via the variable gain amplifier (AGC) 8 and the variable gain amplifier 8 is digitally digitalized. The image signal output from the image sensor 5 is converted to a digital image signal at a predetermined sampling frequency, and is output to the focus adjustment device 15.

 The focus adjustment device 15 processes the digital image signal C output from the imaging device 1 and calculates the MTF of the image pattern in the first chart CH 1 and the second chart CH 2 MT F calculation unit 1 6, MT F comparison unit 2 5, R OM (compares the MT F value of the first chart CH 1 with the MT F of the second chart CH 2 Read only memory) 2 3, CPU (Central Processing Proceeding Unit) 2 4, Buffer 2 6 that temporarily stores image data output from AFE 6, etc. Each process of the focus adjustment device 15 is controlled according to the control program stored in the ROM 2 3.

Note that the function of the focus evaluation value in the present invention is expressed by MTF, and the function of the focus evaluation value detection means in the present invention is expressed by the MTF calculation unit 16. The MTF calculation unit 16 includes a first calculation unit 17 that calculates the MTF of the first test chart CHI and a second calculation unit that calculates the MTF of the second test chart CH2. It consists of 1 and 8.

 Next, based on FIG. 4, a method for measuring MTF in this example will be described. First, when obtaining the MTF, the first test chart CH 1 and the second test chart CH 2 are imaged on the image sensor 5 via the focus lens 3, and the image is obtained from the AFE 6. Data (digital signal C) is output. Then, as shown in FIG. 4 (a), in the first calculation unit 17 and the second calculation unit 18, the photographed first test chart CH 1 and second test chart The number of samples is calculated based on the inclination angle of the edge of the CH 2 imaging pattern, and then the image data is scanned using the calculated number of samples to obtain pixel values. The step response is obtained, then the edge impulse response is obtained by differentiating the step response, and then the impulse response is Fourier transformed to obtain MTF. Specifically, first, as shown in Figs. 4 (a) and (b), the first test chart CH 1 and the second test chart CH The edge inclination angle α in 2 is calculated, and the sampling number な る, which is the basic unit of scanning in one direction of the image, is calculated.

 Next, as shown in FIG. 4 (c), one direction of the image is the main scanning direction and the other direction is the sub scanning direction (in this embodiment, the vertical direction is the main scanning direction and the horizontal direction is the sub scanning direction. Scan the image taken by the image sensor 5. At this time, in the main scanning direction, the image is sequentially scanned by setting the sampling number Ρ to one line. Then, as shown in Fig. 4 (d), the edge step response is obtained by obtaining the pixel value at each scan position.

As shown in Fig. 4 (b), the imaging of test charts CH 1 and CH 2 is shown. If the edge is slightly inclined with respect to the vertical direction, the main scanning direction is the vertical direction, and the sampling number P is set so that the edge line is displaced by one pixel in the vertical direction. Fig. 4 (b) shows the image data obtained by imaging, and each square frame represents a pixel, and 秦, country, ◯, mouth, etc. in the pixel represent pixel values.

 In the first chart CH 1, the brightness on the left side is dark and the brightness on the right side is bright through the edge of the image data, and the brightness on the right side appears brightly. In the second chart CH 2, it appears symmetrically with the first chart. The brightness on the right side is darker and the brightness on the left side is brighter.

 When calculating the inclination angle α, as shown in Fig. 4 (e), the y direction (vertical) is applied to the edges of the first test chart CH 1 and the second test chart CH 2. (S direction) Place S windows w. At this time, one window has a plurality of unit elements in the X direction (horizontal direction), the height of each unit element is the same value as one pixel, and the width is smaller than one pixel. Value.

 Next, using (Equation 1), second-order differentiation is performed in each window w.

L ^w (X) = 2 * P ^w (x)-P ^w (x-1)-P ^w (x + 1) (Equation 1)

In (Equation 1), P ^w (x) is the pixel value at the point (X, E y ^w ) in the window ^w , and L ^w (X) is the second derivative at that point. The point (x, E y ^w ) is the position when one unit element is a scale of X and y coordinates, and E y ^w is 1, 2, 3, corresponds to S.

Next, in each window w, the maximum value L max ^w and the minimum value L min ^w of the secondary differential value L ^w (X) are obtained, and the x coordinates X max ^w and X min ^w of those points are obtained, Using (Equation 2), the X coordinate of the edge point in the window w 內 Find E x ^w .

E x ^w = (X min ^w * | L max ^w | + X max ^w * | L min ^w |) / (| L max ^w | + | L min ^w |) (Equation 2)

 Next, the edge line inclination angle α is obtained from the edge point group obtained from (Equation 2), and the integer value obtained by rounding off cot α at this time is defined as the sampling number Ρ. .

 Next, the step response calculation units 17 b and 18 b are moved to. First, as shown in FIG. 4 (c), the pixels in the first column are divided by the sampling number P along the vertical direction. After scanning the first row, move the scan position in the horizontal direction, scan again in the vertical direction by the number of samplings P, and sequentially scan the area image data. Scan a number of samples along the vertical direction.

 Next, as shown in Fig. 4 (d), the pixel values at each scan position are unified and the edge step response is obtained. In Fig. 4 (d), the vertical axis represents the brightness value, and the horizontal axis represents the position when each scan position is unfolded. In other words, the step response calculation units 17 b and 18 b scan the pixel values near the edge by the number of samplings P in the vertical direction, and arrange the pixel values in the scanned order. Thus, an edge step response can be obtained.

 Next, the impulse response calculation sections 17 c and 18 c move to the impulse response by differentiating the step responses obtained by the step response calculation sections 17 b and 18 b. Convert. The differentiation performed here can be performed, for example, by taking the difference between adjacent pixels of the step response.

Next, the process moves to the MTF calculation units 17 d and 18 d, and the impulse response obtained by the impulse response calculation units 17 c and 18 c is subjected to Fourier transform to obtain the MTF. Ask. At this time, the Fourier transform is performed for each frequency. The real part and the imaginary part are obtained, and MTF is obtained by adding the real part and the imaginary part. Further, the MTF calculation method is not limited to this, and for example, the resolution measurement method described in ISO 1 2 2 3 3 may be used.

 Next, based on FIG. 5, the procedure for obtaining the in-focus position of the focus lens 3 using the first test chart CH 1 and the second test chart CH 2 will be described. . This procedure is executed by giving a command signal to each functional unit based on the program in which C P U 2 4 is stored in ROM 2 3. In addition, S in FIG. 5 represents a step.

 First, this procedure starts when an activation signal is input to the focus adjustment device 15 by the operator.

 Next, in S 1 0 1, the focus lens 3 is moved to a predetermined initial position, and the process proceeds to S 1 0 2.

 Next, in S 1 0 2, imaging of the first chart CH 1 and the second test chart CH 2 is started, and in S 1 0 3, the image data output via the AFE 6 is Output to the focus detection device 1 5.

 Next, in S 10 4, the first calculation unit 17 calculates and obtains the MTF of the imaging pattern in the first test chart CH 1, and the second calculation unit 1 8 calculates the second Calculate the MTF of the imaging pattern in the test chart CH 2 and then move to S 1 0 5.

 Next, in S 1 0 5, the difference between the MT F at the predetermined frequency calculated by the first calculation unit 17 and the MT F at the predetermined frequency calculated by the second calculation unit 18 is calculated, and then S 1 0 Go to 6. At this time, since the MTF can be calculated for each frequency component, the MTF corresponding to a predetermined high frequency component may be compared.

Next, in S 1 0 6, it is determined whether or not the difference between the MT F calculated by the first calculation unit 17 and the MT F calculated by the second calculation unit 1 8 is zero ( So-called MTF obtained by photographing the first test chart CH 1 and MTF obtained by photographing the second test chart 卜 CH 2 are determined. In S 1 0 6, if the difference between the two is zero (Y es), the focus lens 3 is in the in-focus position, and the processing is terminated (END), and the difference between the two is If it is not zero (N o), go to S 1 0 7. Next, in S 1 0 7, the focus lens 3 is moved by a predetermined amount along the optical axis X, and then S 1 0 3 force and S 1 0 6 are repeated, and in S 1 0 6 the difference between the two When the value reaches zero, this process is terminated.

 As described above, according to the focus adjustment method and the focus adjustment device in the imaging device 1 described in the embodiment, the object P is moved back and forth on the optical axis X via the target position of the subject P.

A first test chart C H 1 and a second test chart C H 2 having an imaging pattern defined in white and black are set, and a focus lens

3 is moved in the direction of the optical axis X, and the image sensor is associated with the amount of movement of the force lens 3 for each of the first test CH 1 and the second test CH 2. Find the MTF of the imaging pattern imaged in Fig. 5, and focus lens so that the MTF of the first test chart CH 1 and the MTF of the second test chart CH 2 match. Set the position of 3.

Even if the peak point of the focus evaluation value is unclear, the focus position can be adjusted with high accuracy and the adjustment can be facilitated.

 In addition, according to the eyelash adjustment method, the point Ifei adjustment method, and the focus adjustment device in the imaging device 1 according to the embodiment of the present invention, the first test chart CH 1 and the first test chart CH 1 separated along the optical axis X The second test chart CH 2 is sometimes used as a fe image, and the work for adjusting the focus is easy, and the accuracy is better than that. The focus position of the power lens 3 can be detected.

As mentioned above, although one Example of this invention was described, this invention is not limited to the said Example, It can take various aspects. For example, as shown in FIG. 6, in the first test chart CH 1 and the second test chart CH 2, a plurality of sample images having inclined edges may be obtained. As a result, when there is a single imaging pattern, the influence of noise can be reduced and a focus evaluation value can be obtained with high accuracy. Also

By arranging a plurality of imaging patterns at a plurality of positions, the focal position in the image can be set according to the application, and the added value can be improved.

 In this embodiment, the position where the difference between the MTF value of the first test chart CH 1 and the MTF value of the second test chart CH 2 is zero is set as the in-focus position. When a predetermined value range is reached, the focus position may be set.

 Further, in this embodiment, a chisel with white and black imaging patterns is used, but a chart having other colors (for example, red, green, blue) is used, and focusing on a specific color component is performed. You can make adjustments.

 In the present embodiment, an imaging apparatus having a so-called autofocus function having the drive unit 12 (electric) of the focus lens 3 has been described.

The invention, rather than being limited to the image pickup apparatus equipped with O over Tofoka scan function, leaving at ¹ applied to an imaging device for adjusting the position of the full O one month scan lens 3 manually. In this case, for example, the focus lens 3 may be aligned along the optical axis X and screwed at the in-focus position.

 Further, when the present invention is applied to an image pickup apparatus having an autofocus,

Find the focal point of the focus lens 3 using the present invention,

2 3 and 1¾ may be used as auto focus parameters. Industrial applicability

 INDUSTRIAL APPLICABILITY The present invention is useful for setting an imaging lens at an in-focus position using an image signal obtained via an imaging element such as CCD provided in the imaging apparatus.

Claims

The scope of the claims 1. In an imaging device using: an imaging lens that guides a subject image to an imaging device; and the imaging device that photoelectrically converts the subject image guided through the imaging lens and outputs an image signal. A focus adjustment method for moving the imaging lens along an optical axis connecting the imaging device and focusing the subject image guided to the imaging device,  On the optical axis, first and second test charts having imaging patterns defined in white and black are set before and after the target position of the subject,  The imaging lens is moved in the optical axis direction, and the imaging pattern imaged on the imaging element is associated with the amount of movement of the imaging lens for each of the first and second test charts. The focus evaluation value of  The position of the imaging lens is set so that the focus evaluation value in the first test chart matches the focus evaluation value in the second test chart. A focus adjustment method in an imaging apparatus.  2. The first test chart and the second test chart are arranged symmetrically via an orthogonal line orthogonal to the optical axis, and are arranged at positions where they do not overlap each other. The focus adjustment method for an imaging apparatus according to claim 1, wherein the focus adjustment method is used.  3. The focus evaluation value is an index representing the amount of spatial frequency components in the edge portion of the imaging pattern. 3. The focus adjustment method for an image pickup apparatus according to claim 1, wherein the focus adjustment method is used. 4. In the first test chart and the second test chart, a plurality of the imaging patterns are arranged side by side. The focus adjustment method for an image pickup apparatus according to claim 1 characterized by this.  5. an imaging lens for guiding the subject image to the image sensor;  An image sensor that photoelectrically converts a subject image guided through the imaging lens and outputs image signals of a plurality of colors;  A focus evaluation value detecting means for detecting a focus evaluation value of the subject image formed on the image sensor in association with a moving amount of the imaging lens; With  A focus adjustment device in an imaging apparatus, wherein the imaging lens is set at a predetermined position based on a detection result detected by the focus evaluation value detection means,  First and second test charts having an imaging pattern defined in white and black are set along the optical axis and back and forth through the target position of the subject,  The focus evaluation value detecting means determines the focus evaluation value of the imaging pattern imaged on the imaging element in association with the movement amount of the imaging lens for each of the first and second test charts. Forget  The position of the imaging lens is set so that the focus evaluation value of the first test chart matches the focus evaluation value of the second test chart. Adjustment device.  6. The first and second test charts are configured symmetrically via an orthogonal line orthogonal to the optical axis, and are configured not to overlap each other. The focus adjustment in the imaging device according to claim 5, characterized in that apparatus.  7. The focus evaluation value is an index representing the component amount of the spatial frequency in the edge portion of the imaging pattern, 7. The focus adjustment device for an image pickup device according to claim 5, wherein the focus adjustment device is an image pickup device.