JP2017219650A - Zoom lens and imaging system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an imaging system that achieves accurate tracking with regard to a focus point in a zoom region and entire focus region in an arbitrary wavelength region from a visible region to a near infrared region in a system in which a picture can be taken in the arbitrary wavelength region from the visible region to the near infrared region.SOLUTION: In an imaging system having a zoom lens allowing a picture to be taken from a visible light region to a near infrared light region, the zoom lens has: a variable magnification group for varying a magnification; a focus lens group for focusing; and a tracking adjustment group for correcting a focus deviation when varying the magnification. The tracking adjustment group is configured to be driven in conjunction with a variable magnification group position and a focus lens position according to a prescribed tracking table; determine a wavelength region of a shooting environment from a focusing position of the focus lens group in at least three prescribed zoom positions with regard to an arbitrary subject; and correct tracking data.SELECTED DRAWING: Figure 1

Description

  The present invention relates to an improvement in focusing accuracy in an arbitrary wavelength region from a visible region to a near infrared region in a zoom lens and an image pickup apparatus having the same, a television camera for broadcasting, a video camera, a digital still camera, a silver salt photography camera, and the like It is suitable for.

  In recent years, in the field of imaging devices such as TV cameras, digital cameras, video cameras, etc., HDTV (high definition) and higher definition 4K support have progressed, and more precise focusing accuracy is required to realize higher definition images. Is required.

  In addition, user needs for photographing environments are diversified, and imaging devices capable of photographing from the visible light region to the infrared light region have been developed. In addition to shooting in the visible light range in normal bright environments, widening the shooting wavelength range to ensure light intensity under dusk, etc., or in situations where a visible light source cannot be used for subjects in dark environments such as at night The (near) infrared imaging is known.

  However, in a zoom lens that is an imaging optical system, it is difficult to correct chromatic aberration over the entire region from the visible light region to the infrared light region, and a zoom lens designed for photographing in the visible light region is When mounted on an imaging device capable of photographing from the visible light region to the infrared region and used in the infrared region, the position of the focus lens in the focused state in photographing in the infrared region is the same as in photographing in the visible light region. Unlike the position of the focus lens, the focusing accuracy deteriorates. Even if flange back adjustment is performed using infrared light, it is difficult to keep focusing (tracking) throughout the entire zoom range.

  As a means for solving the above problem, it is necessary to suppress axial chromatic aberration over the entire range from the visible light region to the infrared light region for the zoom lens. For this purpose, it is necessary to use many low-dispersion glass types having anomalous dispersion such as fluorite for the lens, which makes the lens expensive and difficult to reduce in size and weight.

  In Patent Document 1 and Patent Document 2, a focus lens and a flange back adjustment lens are separately provided, and a correction amount table by the flange back adjustment lens is provided for each imaging wavelength range, and the focus lens position and the zoom position position are determined. By driving the flange back adjustment lens based on the correction amount table, the imaging positions are matched in the visible light region and the infrared region.

  In Patent Literature 3, Patent Literature 4, and Patent Literature 5, a color separation prism for separating subject light into visible light and infrared light in the optical path of the photographing lens, and imaging in the infrared optical path. A correction lens for correcting the position is arranged. The correction lens enables simultaneous focusing with visible light and infrared light.

Japanese Patent Laid-Open No. 2003-262775 JP 2006-162757 A JP 2004-354714 A JP 2005-4181 JP 2005-128485 A

  In Patent Documents 1 to 5, in order to realize accurate tracking over the entire zoom range, it is necessary to prepare correction data for each wavelength region that is supposed to be imaged, and the amount of data stored in advance is increased. End up. In addition, it is necessary to instruct the wavelength region to be photographed by the user, in other words, correction data to be used. In particular, when the wavelength characteristic of the light source used for photographing is unknown, accurate tracking is difficult.

  In Patent Document 3, Patent Document 4, and Patent Document 5, it is necessary to provide a color separation prism and an optical system for image formation after separation in the optical path of the photographing lens, and it is difficult to reduce the size of the system. is there.

  Accordingly, an object of the present invention is to provide a zoom lens and an imaging system that realizes accurate tracking over the entire focus range and the entire zoom range in an arbitrary wavelength region from the visible light region to the infrared region.

In order to achieve the above object, an imaging system according to the present invention provides:
In an imaging system that has a zoom lens that can shoot from the visible light region to the infrared light region, the zoom lens has a zooming group for zooming, a focusing lens group for focusing, and defocusing during zooming. A tracking adjustment group for correction is provided, and the tracking adjustment group is driven in conjunction with a zooming group position and a focus lens position according to a predetermined tracking table, and at least three predetermined zooms for an arbitrary subject. It is preferable to correct the tracking data by specifying the wavelength region of the shooting environment from the focus position of the focus lens group at the position.

  Preferably, in the zoom lens having a focus lens group for focusing, a zooming group for zooming, and a tracking adjustment group for correcting a focus shift during zooming in order from the object side, the position of the zooming group And a correction table B indicating the position of the tracking adjustment group with respect to the position of the focus group, and a correction coefficient α calculated from the focus position of the focus lens group at at least three predetermined zoom positions with respect to an arbitrary subject Therefore, the tracking data of the tracking adjustment group is preferably α · B.

Further, in order from the object side, the zoom lens has a zooming group for zooming and a focus lens group for focusing, and the focus lens group is a zoom lens that is also used as a tracking adjustment group. It has a tracking table A in the reference wavelength region that shows the position of the tracking adjustment group relative to the position of the focus group, and a correction table B. The position of the zooming group and the position of the tracking adjustment group relative to the position of the focus group The tracking data of the tracking adjustment group is obtained from the correction coefficient α calculated from the focus position of the focus lens group at at least three predetermined zoom positions with respect to an arbitrary subject. B is better.
Of the three predetermined zoom positions, two may be a wide-angle end and a telephoto end.

  Further objects and other features of the present invention will be made clear by the preferred embodiments described below with reference to the accompanying drawings.

  According to the present invention, in a system capable of photographing in an arbitrary wavelength region from the visible region to the near infrared region, the focus is accurate over the entire zoom range and the entire focus region in the arbitrary wavelength region from the visible region to the near infrared region. It is possible to provide an imaging system that achieves accurate tracking.

System diagram of the present invention Tracking data schematic Example 1 flow chart Sectional view when focusing on infinity at the wide-angle end in Numerical Example 1 Spherical aberration diagram at the wide-angle end and 2.5m in focus in Numerical value example 1 Spherical aberration diagram at the telephoto end of Numerical Example 1 at 2.5 m in focus Spherical aberration diagram at the telephoto end and infinite focus in Numerical Example 1 Spherical aberration diagram at the telephoto end and closest focus of Numerical Example 1

  Hereinafter, embodiments for carrying out the present invention will be described with reference to the drawings.

(Embodiment 1)
FIG. 1 shows the configuration of an imaging system that is Embodiment 1 of the present invention.

  In FIG. 1, reference numeral 114 denotes an imaging device such as a television camera or a video camera, and reference numeral 101 denotes a zoom lens that can be attached to and detached from the camera 114. Reference numeral 117 denotes a drive unit (control device) attached to the zoom lens 101. Reference numeral 116 denotes an imaging system. The zoom lens 101 and the drive unit 117 constitute an imaging system.

  In this zoom lens system, power is supplied through a cable 121 (or a contact connector connected when the zoom lens 101 and the camera 114 are combined) 121 connecting the camera 114 and the drive unit 117.

  In the zoom lens 101, reference numeral 102 denotes a fixed lens unit, and reference numeral 103 denotes a zoom lens unit that can move in the optical axis direction for zooming. Reference numeral 104 denotes an aperture unit that changes the aperture diameter for light quantity adjustment, and reference numeral 105 denotes a focus lens unit that can move in the optical axis direction for automatic focusing. The lens units 102 to 105 and the aperture unit 104 constitute a photographing optical system, and this zoom lens is a rear focus type zoom lens.

  Reference numeral 108 denotes a zoom drive mechanism such as a cam that drives the variable magnification lens unit 103 in the optical axis direction, and reference numeral 118 denotes a focus drive mechanism such as a feed screw that drives the focus lens unit 105 in the optical axis direction.

  The zoom drive mechanism 108, the focus drive mechanism 118, and the aperture unit 104 can be electrically driven by the drive unit 117, and can also be driven manually.

  On the other hand, in the camera 114, reference numeral 106 denotes a glass block corresponding to a filter or a color separation prism, and 107 denotes an image sensor such as a CCD or a CMOS sensor that photoelectrically converts a subject image formed by a photographing optical system. Reference numeral 115 denotes a camera control circuit that controls the camera 114, and includes a CPU that performs various arithmetic processes, an image processing circuit that performs various image processes on an image pickup signal from the image sensor 107, and the like.

  In the drive unit 117, reference numeral 112 denotes a lens control circuit for controlling various operations of the drive unit 117. The lens control circuit 112 stores a CPU for performing various arithmetic processes and a tracking data table to be described later. The data memory circuit 112a and a motor driver circuit to be described later are incorporated.

  The tracking data is data indicating the subject distance and the position of the focus lens unit 105 for maintaining the in-focus state with respect to each zoom position. In this embodiment, each subject distance and the drive of the zoom drive mechanism 108 are recorded. The position, in other words, the position of the zoom lens unit 103 on the optical axis is stored in the data memory circuit 112a as the drive position of the focus drive mechanism 118, in other words, the position data on the optical axis of the focus lens unit 105. . Here, zoom tracking curve data and flange back adjustment in the present embodiment will be described.

  FIG. 2 schematically shows zoom tracking curve data for the zoom lens 101. In FIG. 2, the horizontal axis indicates the position of the zoom lens unit 103, that is, the zoom position, and the vertical axis indicates the position of the focus lens unit 105, that is, the focus lens position. Here, the subject distance is the focus of the zoom lens. The data at the shortest possible distance and the data at an infinite distance are shown.

  Here, as can be seen from FIG. 2, when the zoom position is at the wide-angle end, the difference in focus lens position where focus is obtained between the subject distance from infinity to the closest distance is small, and the zoom position is at the telephoto end. In this case, there is a large difference in focus lens position at which focusing can be obtained when the subject distance is between infinity and the closest distance. This difference in focus lens position is generally proportional to the square of the focal length.

  In order to perform focus maintaining control for zooming in the zoom lens actually mounted on the imaging device 114 using this tracking data, the focus state is set based on the reference position on the tracking data and the shooting condition of the reference position. It is necessary to match the position of the focus lens unit 105 at a certain time. This is called flange back adjustment. The flange back adjustment is to correct the variation in the position of the image sensor 107 on the optical axis from the reference plane where the zoom lens 101 of the image sensor 114 is mounted in the model of the image sensor 114 and individual products.

  Further, the flange back changes depending on the use environment of the photographing system such as temperature and humidity. Therefore, it is necessary to adjust the flange back every time the camera is mounted on a different camera, each time shooting is performed in a different usage environment, and each time the power is turned on. The drive unit 117 will be described. Reference numeral 109 denotes a zoom motor that operates in accordance with a drive signal from the lens control circuit 112 and drives the zoom drive mechanism 108. Reference numeral 111 denotes a focus motor that operates in accordance with a drive signal from the lens control circuit 112 and drives the focus drive mechanism 118.

  The drive unit 117 is provided with a zoom position detector 119 such as an encoder or a potentiometer connected to the zoom drive mechanism 108 in order to detect the position of the zoom lens unit 103 on the optical axis. The circuit 112 controls the position of the focus lens unit 105 on the optical axis via the focus motor 111 based on the detection signal from the zoom position detector 119 and the tracking data.

  Thereby, the in-focus state is maintained over the entire zoom range. In addition, in order to detect the position of the focus lens unit 105 on the optical axis, a focus position detector 120 such as an encoder or a photo sensor connected to the focus drive mechanism 118 is provided.

  Reference numeral 110 denotes an aperture drive circuit that drives the aperture unit 104 in the zoom lens 101 in accordance with a drive signal from the lens control circuit 112. Reference numeral 113 denotes a switch for the user to instruct execution of flange back adjustment. An operation signal from the switch 113 is input to the lens control circuit 112.

  FIG. 3 shows a flowchart of flange back adjustment and tracking data correction in the imaging system 116.

  First, in step (denoted as S in the figure) 11, whether or not the lens control circuit 112 has received an operation start signal from the flange back adjustment switch 113 or whether or not power supply from the imaging device 114 or the outside has been started. When the operation start signal is input or when the power supply is started, the process proceeds to step 12.

  In step 12, the aperture is driven to the open state. Thereby, since the depth of focus becomes shallow and the accuracy of focusing increases, highly accurate flange back adjustment and tracking data correction can be performed.

  In step 13, the lens circuit 112 drives the zoom motor 108 to move the zoom lens unit 103 to the zoom position a.

  In step 14, the lens circuit 112 performs in-focus position detection by a contrast detection method or the like based on the video signal received from the camera control circuit 115. In the case of the contrast detection method, the lens control circuit 112 extracts a high-frequency component of the video signal, and moves the focus lens unit 105 by a predetermined amount by driving the focus motor 111 until the peak of the extracted high-frequency component becomes maximum. The focus detection is repeated (step 15). In the case of using the phase difference detection method, the lens control circuit 112 compares the two video signals obtained by capturing the same 11 of the subject and performs focus detection.

  In step 16, focus determination is performed by the method in step 15. When it is determined that the in-focus state has been obtained, the process proceeds to step 17.

  In step 17, the position on the optical axis of the focus lens unit 105 at the time of focusing (the position of the focus drive mechanism 118) is detected by the focus position detector 120 described above and stored in the data memory 112a or a memory circuit (not shown). To do.

  In step 18, the lens control circuit 112 drives the zoom motor 109 to move the zoom lens unit 103 to a predetermined zoom position b.

  In step 19, the lens control circuit 112 performs in-focus position detection using a contrast detection method or the like based on the video signal received from the camera control circuit 115. The focus position detection method is the same as in step 15 (step 21).

  In step 20, in-focus determination is performed. When it is determined that the in-focus state has been obtained, the process proceeds to step 22.

  In step 22, the position on the optical axis of the focus lens unit 105 at the time of focusing (the position of the focus drive mechanism 118) is detected by the focus position detector 120 described above and stored in the data memory 112a or a memory circuit (not shown). To do.

  In step 23, the lens control circuit 112 calculates the reference position of the tracking table from the position on the optical axis of the focus lens unit 105 stored in step 17 and step 22.

  In step 24, the lens control circuit 112 drives the zoom motor 109 to move the zoom lens unit 103 to a predetermined zoom position c.

  In step 25, the lens control circuit 112 performs in-focus position detection using a contrast detection method or the like based on the video signal received from the camera control circuit 115. The focus position detection method is the same as in step 15 (step 27).

  In step 26, focus determination is performed. When it is determined that the in-focus state is obtained, the process proceeds to step 28.

  In step 28, the position on the optical axis of the focus lens unit 105 at the time of focusing (the position of the focus drive mechanism 118) is detected by the focus position detector 120 described above and stored in the data memory 112a or a memory circuit (not shown). To do.

  In step 29, subject distance information of the tracking data is calculated from the tracking data based on the reference position obtained in step 23 and the position on the optical axis of the focus lens unit 105 stored in steps 17 and 22.

  In step 30, the correction coefficient α is determined from the difference between the focus lens unit position at the zoom position c in the tracking data A at the subject distance obtained in step 29 and the focus position at the zoom position c obtained in step 28. calculate.

  In step 31, the lens control circuit 112 corrects the tracking data based on a predetermined arithmetic expression.

  In the present embodiment, the case where the drive unit 117 is mounted on the zoom lens 101 and the zoom lens system is configured has been described. However, the present invention relates to the case where the drive unit 117 is incorporated in the zoom lens. Can also be applied.

Examples of zoom lenses to which the tracking data correction control described in the above embodiment can be applied are described above. In FIG. 4, in order from the object side, I is a lens unit for manual focusing, II is a variable power lens unit that can be moved for zooming, and III is for correcting the movement of the imaging position during zooming. Correction lens unit, SP is aperture, IV is fixed lens unit, V is autofocus, flange back adjustment, or lens unit GB for tracking data correction is glass block such as color separation prism, IP is image sensor It is. The lens unit I and the fixed lens unit IV are fixed at the time of zooming. Table 1 shows numerical examples of zoom lenses corresponding to FIG.

(Numerical example 1)
Unit mm

Surface data surface number rd nd vd Effective diameter
1 1169.481 2.40 1.81265 25.4 69.39
2 98.429 10.83 1.51825 64.2 68.86
3 -265.170 0.20 69.02
4 124.037 8.29 1.60548 60.7 68.76
5 -281.395 0.20 68.45
6 51.797 6.46 1.64254 60.1 61.58
7 97.915 (variable) 60.59
8 71.045 0.90 1.82017 46.6 23.36
9 17.601 6.01 19.91
10 -21.542 0.90 1.77621 49.6 19.28
11 18.397 4.63 1.85501 23.9 19.28
12 -4295.134 (variable) 19.19
13 -27.245 0.90 1.79013 44.2 18.72
14 31.613 3.84 1.85501 23.9 20.69
15 1125.345 (variable) 21.58
16 (Aperture) ∞ 1.60 22.82
17 10000.000 8.10 1.61671 55.0 24.16
18 -15.601 1.20 1.82017 46.6 25.04
19 -37.306 0.20 28.26
20 110.820 5.22 1.62508 53.2 30.57
21 -51.132 37.00 30.98
22 786.500 1.20 1.81264 25.4 30.16
23 25.913 7.96 1.66152 50.9 30.00
24 -77.604 0.20 30.17
25 37.803 5.34 1.66152 50.9 29.71
26 -1000.000 3.80 28.85
27 ∞ 29.00 1.60718 38.0 30.00
28 ∞ 11.20 1.51825 64.2 30.00
29 ∞ (variable) 30.00
Image plane ∞

Various data Zoom ratio 14.67
Wide angle Medium Telephoto focal length 7.60 29.11 111.48
F number 1.52 1.52 2.32
Angle of View 27.76 7.83 2.05
Image height 4.00 4.00 4.00
Total lens length 225.47 225.47 225.47
BF 13.04 13.04 13.04

d 7 0.39 33.91 49.55
d12 52.91 14.80 3.78
d15 1.55 6.13 1.53
d29 13.04 13.04 13.04

Entrance pupil position 40.71 180.89 487.71
Exit pupil position 170.26 170.26 170.26
Front principal point position 48.67 215.38 678.26
Rear principal point position 5.44 -16.06 -98.44

Zoom lens group data group Start surface Focal length Lens configuration length Front principal point position Rear principal point position
1 1 76.58 28.38 11.12 -6.50
2 8 -13.79 12.44 3.16 -5.86
3 13 -36.06 4.74 0.03 -2.54
4 16 45.24 112.02 54.95 -85.67

Single lens Data lens Start surface Focal length
1 1 -132.38
2 2 139.93
3 4 143.29
4 6 162.26
5 8 -28.75
6 10 -12.66
7 11 21.44
8 13 -18.40
9 14 37.98
10 17 25.27
11 18 -33.53
12 20 56.68
13 22 -33.00
14 23 30.29
15 25 55.18
16 27 0.00
17 28 0.00

In the zoom lens of FIG. 4, the closest distance that can be focused over the entire zoom range is 432 mm from the front surface of the zoom lens. When distance L is the closest distance that can be focused over the entire zoom range, the present invention is effective for a subject between infinity and distance L. For subject distances outside the above range, flange back is effective. The accuracy of adjustment and tracking data correction is reduced.
FIG. 5 shows a spherical aberration diagram when focusing on a distance of 2.5 m from the wide-angle end of the first numerical embodiment and the apex of the first surface of the lens. FIG. 6 shows a spherical aberration diagram when focusing on the telephoto end and the object distance of 2.5 m. FIG. 7 shows a spherical aberration diagram when focusing on the telephoto end and the object distance at infinity. FIG. 8 shows a spherical aberration diagram when the telephoto end and the object distance are in focus at 432 mm from the forefront.

  The unit of the horizontal axis of each aberration diagram is mm. The spherical aberration solid line indicates the d line, the dotted line indicates the F line, the single oblique line indicates the C line, and the double oblique line indicates 950 nm. The difference in back focus and spherical aberration at each wavelength is the difference in focus position depending on the imaging wavelength region.

  Table 1 shows reference tracking data A. The tracking data is composed of a focus extension amount value with respect to the focal length of the zoom lens (vertical axis in Table 1) and the subject distance (horizontal axis in Table 1). The positive / negative sign is negative on the object side and positive on the imaging plane side. Values between tracking data not listed in Table 1 should be obtained by linear interpolation using the nearest values. In Table 1, as an example, the focal length is 3 and the subject distance is 4 divisions. However, the number of divisions is the difference between the focus advance amount obtained by the linear approximation and the focus advance amount required for the actual device. It is good to set so that it may correspond to the range of the depth of focus which is not recognized as.

  As an example, Table 1 was calculated from the three wavelengths of d-line, F-line, and C-line, which are wavelengths in the visible light region. Since the tracking table A is a reference, it is preferable that the tracking table A is in a wavelength region that is considered to be most frequently used in the imaging system.

  The tracking data A is the average value of the focus lens extension calculated based on the paraxial theory calculated for each of the three wavelengths, and the entire table is transitioned uniformly so that the infinity value at the wide-angle end of 7.6 mm becomes zero. ing.

  When calculating the focus extension amount, it is preferable to calculate from the position on the optical axis where the MTF value considering the spherical aberration takes a peak. Further, it is preferable to calculate with a plurality of wavelengths and weights between wavelengths in consideration of spectral sensitivity of the image sensor, spectral characteristics of various filters inserted in the light source and the imaging system, and the like. As a result, more accurate focus tracking is possible.

  Next, Table 2 shows the correction data B.

  To achieve accurate tracking in the entire zoom range and focus range in any wavelength region from visible to near-infrared in a system that can shoot in any wavelength region from visible to near-infrared. The correction data B is necessary for correcting the tracking data A. It consists of a focus extension correction value for the focal length of the zoom lens (vertical axis in Table 2) and subject distance (horizontal axis in Table 2). The positive / negative sign is negative on the object side and positive on the imaging plane side. Values between correction data not listed in Table 2 should be obtained by linear interpolation using the nearest values.

  In Table 2, as an example, like the tracking data A, the focal length is three and the subject distance is four. However, the number of divisions is obtained by the linear approximation after correction by the tracking data A and the correction data B. It is preferable that the difference between the focus extension amount and the focus extension amount necessary for the actual machine is set so as to correspond to the range of the depth of focus where blur is not recognized.

  The correction data B is calculated from the tracking data (not shown) calculated from a wavelength different from that used for calculating the tracking data A and the difference in Table 1. The wavelength region used for calculating the correction data B is preferably as far away as possible from the wavelength region used for calculating the reference tracking data A within the imaging wavelength range assumed by the imaging system of the present invention. As a result, focus tracking with higher accuracy can be performed in a wide wavelength range.

  Table 2 was created from the tracking data (not shown) calculated from the wavelength of 950 nm in the near infrared region and the difference in Table 1 as an example.

  The correction data B was calculated from the amount of extension of the focus lens based on the paraxial theory at the wavelength of 950 nm. Tracking data calculated from a wavelength of 950 nm (not shown) is linearly approximated using the linear approximation so that the value at the telephoto end of 111.5 mm becomes 0. When calculating the focus extension amount, it is preferable to calculate from the position on the optical axis where the MTF value considering the spherical aberration takes a peak. Further, it is preferable to calculate with a plurality of wavelengths and weights between wavelengths in consideration of spectral sensitivity of the image sensor, spectral characteristics of various filters inserted in the light source and the imaging system, and the like. Thereby, focusing with higher accuracy is possible.

  When intermediate values of the tracking table A and the correction table B are necessary, it is preferable to approximate the two conditions linearly. The tracking table A and the correction table B use values calculated by paraxial theory, but using the best focus position taking spherical aberration into consideration makes it possible to achieve higher accuracy of focusing. Further preferred.

  The preferred embodiments of the present invention have been described above, but the present invention is not limited to these embodiments, and various modifications and changes can be made within the scope of the gist. In order from the object side, I is a lens unit for manual focusing, II is a variable power lens unit that can be moved for zooming, and III is a correction lens for correcting the movement of the imaging position during zooming. Unit, SP is an aperture, IV is a fixed lens unit, V is a lens unit for automatic focusing, flange back adjustment, or tracking data correction, GB is a glass block such as a color separation prism, and IP is an image sensor. The lens unit I and the fixed lens unit IV are fixed at the time of zooming.

I lens group fixed during zooming, II zooming lens unit movable for zooming,
III Correction lens unit to correct the movement of the imaging position during zooming,
IV fixed lens unit,
V Lens unit for automatic focusing, flange back adjustment, or tracking data correction,
GB glass block, SP aperture, IP image sensor

Claims (4)

In an imaging system that has a zoom lens that can shoot from the visible light region to the infrared light region, the zoom lens has a zooming group for zooming, a focusing lens group for focusing, and defocusing during zooming. A tracking adjustment group for correction is provided, and the tracking adjustment group is driven in conjunction with a zooming group position and a focus lens position according to a predetermined tracking table, and at least three predetermined zooms for an arbitrary subject. An imaging system, wherein a wavelength region of an imaging environment is specified from a focus position of a focus lens group at a position, and tracking data is corrected.   In order from the object side, a zoom lens having a focus lens group for focusing, a zooming group for zooming, and a tracking adjustment group for correcting a focus shift during zooming, the position of the zooming group and the focus It has a correction table B indicating the position of the tracking adjustment group relative to the position of the group, and tracking from a correction coefficient α calculated from the focus position of the focus lens group at at least three predetermined zoom positions for any subject The imaging system according to claim 1, wherein tracking data of the adjustment group is α · B. In order from the object side, there are a zooming group for zooming and a focus lens group for focusing, and the focus lens group is a zoom lens that is also used as a tracking adjustment group. It has a tracking table A in the reference wavelength region showing the position of the tracking adjustment group relative to the position, and a correction table B, showing the position of the zooming group and the position of the tracking adjustment group relative to the position of the focus group It has a correction table B, and tracking data of the tracking adjustment group is expressed as A + α · B from a correction coefficient α calculated from the focus position of the focus lens group at at least three predetermined zoom positions for an arbitrary subject. The imaging system according to claim 1, wherein: 2. The photographing system according to claim 1, wherein two of the three predetermined zoom positions are a wide-angle end and a telephoto end.