JP2014085429A - Optical system and image capturing device having the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an optical system which has a wide view angle but easily provides high quality images in the entire screen and easily maintains good optical performance even when an anti-vibration mechanism is in action.SOLUTION: An optical system has a focal length shorter than a back focal length and includes an aperture stop and a lens group Lis which shifts an image forming position in a direction perpendicular to the optical axis by moving in a direction having a component perpendicular to the optical axis. The lens group Lis includes one or more positive lenses and one or more negative lenses. A focal length f of the entire system, a focal length fis of the lens group Lis, a distance Dis along the optical axis between the aperture stop and a surface of a lens of the anti-vibration lens group Lis located farthest from the aperture stop, and a distance DL between a surface of a lens on the most object side and a surface of a lens on the most image side are each set appropriately.

Description

  The present invention relates to an optical system, and is suitable for an imaging optical system used in an imaging apparatus such as a silver salt film camera, a digital still camera, a video camera, a digital video camera, a surveillance camera, and a TV camera.

  In recent years, imaging devices such as digital cameras and video cameras have used high-pixel imaging elements. An imaging optical system used in an imaging apparatus including such a high-pixel imaging element is required to have various aberrations corrected well and to have high optical performance over the entire screen. In addition, in order to obtain a higher-definition image, it is required to have an anti-vibration mechanism that suppresses image deterioration due to the influence of vibration such as camera shake during shooting. As an anti-vibration mechanism, there is known a method of correcting a change in image position caused by camera shake or the like by moving a part of a lens group of an optical system in a direction including a component perpendicular to the optical axis. .

  Conventionally, it is known to use an anti-vibration mechanism in a so-called retrofocus type wide-angle lens whose focal length is shorter than the back focus (Patent Document 1). In Patent Document 1, in order from the object side, in a wide-angle lens including a lens group having a negative refractive power and a lens group GL having a positive refractive power, the two most image-side lenses constituting the lens group GL are used. It is disclosed that image stabilization is performed by rotating a positive lens around a point on the optical axis.

JP-A-8-220427

  In the retrofocus imaging optical system, a lens group with negative refractive power is arranged in the front and a lens group with positive refractive power is arranged in the rear, so that shooting with a wide angle of view is possible while ensuring a long back focus. Making it easy. Even in an imaging optical system with a wide angle of view, image blurring occurs when the imaging optical system vibrates. Therefore, it is effective to use an image stabilization function in order to obtain a good image.

  In order to correct image blur when the optical system (imaging optical system) vibrates and obtain good optical performance, an anti-vibration mechanism (anti-vibration lens group) is placed at an appropriate position in the optical path of the imaging optical system. Placement is important. In Patent Document 1, two lenses arranged at a position closest to the image plane side are used as an anti-vibration lens group. For this reason, the incident position of the principal ray of the off-axis ray incident on the vibration-proof lens group becomes high, and there is a tendency that the eccentric aberration fluctuates in the off-axis ray at the time of vibration prevention, and it becomes difficult to correct the aberration at the time of vibration prevention. In addition, the incident height of off-axis rays incident on the image stabilizing lens group increases, and the image stabilizing lens group tends to increase in size.

  In order to correct image blurring when the optical system vibrates while maintaining good optical performance, the lens configuration and refractive power of the anti-vibration lens group, the distance from the aperture stop of the anti-vibration lens group, etc. are appropriate. It is important to set. In particular, it is important for an imaging optical system having a wide angle of view for the purpose of obtaining high optical performance over the entire screen while widening the angle of view. If these elements are inappropriate, a large amount of decentration aberration occurs during image stabilization, and the optical performance is greatly deteriorated.

  An object of the present invention is to provide an optical system that can easily obtain a high-quality image over the entire screen while having a wide angle of view and that can easily maintain good optical performance even during image stabilization.

The optical system of the present invention is an optical system in which the focal length is shorter than the back focus, and the optical system moves in a direction having a component perpendicular to the aperture stop and the optical axis to set the imaging position as the optical axis. The lens unit Lis moves in the vertical direction, and the lens unit Lis includes at least one of a positive lens and a negative lens. The focal length of the entire system is f, and the focal length of the lens group Lis is fis. The length on the optical axis from the aperture stop to the lens surface farthest from the aperture stop of the lens unit Lis is Dis, and the length on the optical axis from the most object side lens surface to the most image side lens surface. When DL is DL
0.08 <f / | fis | <0.50
-0.7 <Dis / DL <0.4
It satisfies the following conditional expression.

  According to the present invention, it is easy to obtain a high-quality image over the entire screen while having a wide angle of view, and an optical system that can easily maintain good optical performance even during image stabilization is obtained.

Lens sectional view of Example 1 Longitudinal aberration diagram of Example 1 (A), (B) Lateral aberration diagrams when the reference state of Example 1 of the present invention and 0.5 ° image stabilization are corrected Lens sectional view of Example 2 Longitudinal aberration diagram of Example 2 (A), (B) Lateral aberration diagrams when the reference state of Example 2 of the present invention and 0.5 ° image stabilization correction are performed Lens sectional view of Example 3 Longitudinal aberration diagram of Example 3 (A), (B) Lateral aberration diagram when the reference state of Example 3 of the present invention and the image stabilization correction of 0.5 ° are performed Lens sectional view of Example 4 Longitudinal aberration diagram of Example 4 (A), (B) Lateral aberration diagram when the reference state of Example 4 of the present invention and the image stabilization correction of 0.5 ° are performed Lens sectional view of Example 5 Longitudinal aberration diagram of Example 5 (A), (B) Lateral aberration diagrams when the reference state of Example 5 of the present invention and 0.5 ° image stabilization are corrected Schematic diagram of main parts of an imaging apparatus of the present invention

  Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings. The optical system of the present invention is an imaging optical system with a wide field angle whose focal length is shorter than the back focus. The optical system includes a lens group Lis that moves in a direction having a component perpendicular to the aperture stop and the optical axis to move the imaging position in a direction perpendicular to the optical axis.

  FIG. 1 is a lens cross-sectional view of Embodiment 1 of the present invention, and FIG. 2 is a longitudinal aberration diagram when focusing on an object at infinity of Embodiment 1. FIGS. 3A and 3B are lateral aberration diagrams when the reference state and the image stabilization correction of 0.5 ° are performed in Example 1 of the present invention. FIG. 4 is a lens cross-sectional view of Embodiment 2 of the present invention, and FIG. 5 is a longitudinal aberration diagram when focusing on an object at infinity of Embodiment 2. 6A and 6B are lateral aberration diagrams when the reference state and the image stabilization correction of 0.5 ° in Example 2 of the present invention are performed.

  FIG. 7 is a lens cross-sectional view of Embodiment 3 of the present invention, and FIG. 8 is a longitudinal aberration diagram when focusing on an object at infinity of Embodiment 3. FIGS. 9A and 9B are lateral aberration diagrams when the reference state and the image stabilization correction of 0.5 ° are performed in Example 3 of the present invention. FIG. 10 is a lens cross-sectional view of Embodiment 4 of the present invention, and FIG. 11 is a longitudinal aberration diagram when focusing on an object at infinity of Embodiment 4. FIGS. 12A and 12B are lateral aberration diagrams when the reference state and the image stabilization correction of 0.5 ° are performed in Example 4 of the present invention.

  FIG. 13 is a lens cross-sectional view of Embodiment 5 of the present invention, and FIG. 14 is a longitudinal aberration diagram when focusing on an object at infinity of Embodiment 5. FIGS. 15A and 15B are lateral aberration diagrams when the reference state and the image stabilization correction of 0.5 ° are performed in the fifth embodiment of the present invention. FIG. 16 is a schematic diagram of a main part of a single-lens reflex camera (imaging device) including the optical system of the present invention.

  The optical system of each embodiment is an imaging optical system used for an imaging apparatus (optical apparatus) such as a digital still camera, a video camera, and a silver salt film camera. In the lens cross-sectional view, the left side is the object side (front), and the right side is the image side (rear). In addition, you may use the optical system of each Example as projection lenses, such as a projector. At this time, the left side is the screen and the right side is the projected image.

  When the optical system of each embodiment is divided into two lens groups with the widest air interval in the optical path as a boundary, or when there is a lens group that performs focusing by moving some lens groups, it moves during focusing. The lens group and the stationary lens group are divided into two lens groups. At this time, the object side is referred to as a front group, and the image side is referred to as a rear group.

  In the lens cross-sectional view, LA is an optical system. LF is a front group of negative refractive power having a plurality of lenses, and LR is a rear group of positive refractive power having a plurality of lenses. SP is an aperture stop. Lis is an anti-vibration lens group (anti-vibration lens group) that moves in a direction having a component perpendicular to the optical axis and moves the imaging position in a direction perpendicular to the optical axis. IP is an image plane. When the imaging optical system of a video camera or digital still camera is used, the imaging surface of a solid-state imaging device (photoelectric conversion device) such as a CCD sensor or a CMOS sensor is a silver salt film camera. Corresponds to the film surface.

  Each longitudinal aberration diagram shows spherical aberration, astigmatism, distortion, and lateral chromatic aberration in order from the left. In the diagrams showing spherical aberration and lateral chromatic aberration, the solid line represents the d line (587.6 nm), and the broken line represents the g line (435.8 nm). In the diagram showing astigmatism, the solid line S represents the sagittal direction of the d line, and the broken line M represents the meridional direction of the d line. Moreover, the figure which shows distortion represents the distortion in d line | wire. In the lateral aberration diagram, the solid line represents the meridional direction of the d line, the broken line represents the sagittal direction of the d line, and the two-dot chain line represents the meridional direction of the g line. Fno is the F number, ω is the half angle of view (degrees) of the shooting angle of view, and hgt is the image height.

  The optical system LA of the present invention is a so-called retrofocus type optical system in which the front group LF is a lens group having a negative refractive power and the rear group LR is a lens group having a positive refractive power. In such an optical system, it is easy to position the image-side principal point on the image side from the final surface (final lens surface) of the entire system, and the entire distance from the final surface of the entire system to the image surface (back focus) It is easy to realize an imaging optical system having a wide field angle with a small focal length of the system. Such an optical system is particularly useful as an imaging optical system for a wide angle of view that requires a long back focus, such as a single-lens reflex camera in which a quick return mirror is disposed on the image plane side of the final surface.

  The optical system of the present invention employs such a retrofocus type, and the aperture stop SP is disposed near the center of the optical system, and the vibration-proof lens group Lis is disposed in the vicinity thereof. In general, in an imaging optical system, the height of an off-axis light beam with the maximum field angle increases as the distance from the aperture stop increases. The tendency becomes more remarkable in the optical system of the present invention. For this reason, the lens disposed at a position away from the aperture stop SP has a large effective beam diameter. Since the off-axis light beam is made up of a light beam that passes near the center of the aperture stop SP, the effective beam diameter is less affected by the angle of view of the off-axis light beam in the lens near the aperture stop SP.

  On the other hand, the axial ray is a ray that determines the F value (F number) of the optical system, and in the case of a retrofocus type wide field angle lens having a relatively short focal length, it is a dominant factor in determining the effective ray diameter of the optical system. It will not be. Therefore, by arranging the aperture stop SP near the center of the optical system, the lens diameters before and after the aperture stop SP can be balanced, and it becomes easy to suppress the increase in the lens diameter as a whole. At this time, the effective diameter of the most object-side lens and the most image-side lens far from the aperture stop SP is large, but the lens near the aperture stop SP arranged near the center of the lens has a small effective diameter.

  In the optical system of the present invention, a lens group located relatively close to the aperture stop SP in the entire system is a vibration-proof lens group Lis that moves so as to have a component perpendicular to the optical axis. As a result, the incident height of off-axis rays passing through the lens group Lis is lowered so that aberration fluctuations of off-axis rays during image stabilization are reduced. Further, the lens group Lis includes at least a positive lens and at least one negative lens, respectively, to facilitate correction of chromatic aberration during vibration isolation and correction of off-axis ray aberration.

  In each embodiment, the imaging position is moved in the direction perpendicular to the optical axis by moving the lens group Lis so as to have a component in the direction perpendicular to the optical axis. In other words, image position fluctuations caused by camera shake or the like are corrected (anti-vibration).

In each embodiment, the focal length of the entire system is f, and the focal length of the lens unit Lis is fis. The length on the optical axis from the aperture stop SP to the lens surface farthest from the aperture stop SP of the anti-vibration lens group Lis is defined as Dis. The length (optical length) on the optical axis from the lens surface closest to the object side to the lens surface closest to the image side is defined as DL. At this time,
0.08 <f / | fis | <0.50 (1)
-0.7 <Dis / DL <0.4 (2)
The following conditional expression is satisfied.

  At this time, the length on the optical axis represents the direction from the object side to the image plane side with a positive sign, and the direction from the image plane side to the object side with a negative sign.

  Conditional expression (1) shows the aberration fluctuation when the refractive power (the reciprocal of the focal length) of the anti-vibration lens unit Lis with respect to the focal length of the entire system is made appropriate and the lens unit Lis is moved in the direction perpendicular to the optical axis. This is to maintain a good balance between the sensitivity of the image and the sensitivity of the image position correction. If the upper limit of conditional expression (1) is exceeded and the refracting power of the lens unit Lis increases, a large amount of decentration aberrations occur during image stabilization and optical performance deteriorates.

  Further, since the correction amount (anti-shake sensitivity) of the image position with respect to the shift amount of the lens unit Lis increases, the shift amount (movement amount) of the lens unit Lis when obtaining a certain anti-shake effect becomes too small. Therefore, it becomes difficult to drive the movement amount with high accuracy in electrical or mechanical manner. Further, when the refractive power of the lens unit Lis becomes weaker beyond the lower limit of the conditional expression (1), the anti-vibration sensitivity becomes too low, and the amount of driving in the direction having the vertical component with respect to the optical axis at the time of anti-vibration becomes large. This is not preferable because the drive mechanism becomes large. More preferably, the numerical range of conditional expression (1) is set as follows.

0.1 <f / | fis | <0.4 (1a)
Conditional expression (2) sets an appropriate distance Dis on the optical axis from the aperture stop SP to the lens surface farthest from the aperture stop SP in the lens unit Lis, and prevents an increase in the size of the lens unit Lis. This is to prevent deterioration of optical performance during vibration isolation. If the upper limit of conditional expression (2) is exceeded and the lens unit Lis is too far from the aperture stop SP and approaches the image plane side, the lens unit Lis is enlarged, which is not preferable. Further, the incident height from the optical axis of the off-axis light beam passing through the lens group Lis becomes high, and it becomes difficult to correct the aberration of the off-axis light beam at the time of image stabilization.

  If the lower limit of conditional expression (2) is exceeded and the lens unit Lis is too far from the aperture stop SP and approaches the object side, the lens unit Lis is similarly enlarged, which is not preferable. Further, the incident height from the optical axis of the off-axis light beam passing through the lens group Lis becomes high, and it becomes difficult to correct the aberration of the off-axis light beam during vibration isolation. More preferably, the numerical range of conditional expression (2) is set as follows.

-0.60 <Dis / DL <0.35 (2a)
According to each embodiment, by specifying the lens configuration as described above, while having high optical performance, the aberration correction at the time of image stabilization is performed well, and an increase in the size of the lens group Lis for image stabilization is suppressed. An optical system with a wide angle of view can be easily obtained.

  In each embodiment, it is desirable to satisfy one or more of the following conditional expressions in order to obtain high optical performance while maintaining good optical performance during vibration isolation. The lateral magnification of the lens group Lis is βis, and the lateral magnification βr of the lens component located on the image side of the lens group Lis. However, the horizontal magnification is a value when focusing on an object at infinity. Let fp be the focal length of the lens lp having the strongest positive refractive power in the lens group Lis, and fn be the focal length of the lens ln having the strongest negative refractive power in the lens group Lis. The Abbe number of the material of the lens lp is νp, and the Abbe number of the material of the lens ln is νn.

  The Abbe number of the lens material having the same sign as the refractive power of the lens group Lis in the lens group lp or lens ln is denoted by νis. The length on the optical axis of the lens group Lis (the length from the most object-side lens surface to the most image-side lens surface) is defined as Tis. The length on the optical axis from the lens surface closest to the object side to the image plane (lens total length) is defined as TL. At this time, one or more of the following conditional expressions should be satisfied.

0.1 <| (1-βis) βr | <0.7 (3)
0.25 <| fp / fn | <4.00 (4)
5 <| νp−νn | (5)
35 <νis (6)
0.03 <Tis / DL <0.30 (7)
2.0 <TL / f <5.0 (8)
Next, the technical meaning of each conditional expression will be described.

  Conditional expression (3) relates to the ratio of the amount of movement of the vertical component with respect to the optical axis of the vibration-proof lens unit Lis and the ratio of the amount of movement of the image point in the vertical direction with respect to the optical axis on the image plane. As the value of conditional expression (3) is larger, the image point can be moved with a smaller amount of movement. Hereinafter, the value defined by the conditional expression (3) is referred to as anti-vibration sensitivity. If the upper limit of the conditional expression (3) is exceeded and the anti-vibration sensitivity is too high, the displacement amount (movement amount) of the anti-vibration lens unit Lis when obtaining a certain anti-vibration effect becomes too small, and the movement amount thereof. It becomes difficult to drive the device electrically or mechanically with high accuracy.

On the other hand, if the vibration sensitivity is too low beyond the lower limit of conditional expression (3), the amount of displacement of the component in the vertical direction with respect to the optical axis at the time of vibration reduction becomes large, which is not preferable.
More preferably, the numerical range of conditional expression (3) is set as follows.

0.12 <| (1-βis) βr | <0.60 (3a)
Conditional expression (4) is the focal point of the lens lp having the strongest (large) positive refractive power and the lens ln having the strongest negative refractive power (absolute value of the negative refractive power) in the anti-vibration lens group Lis. It is specified in the ratio of distance. If the refractive power of either the lens lp or the lens ln is too weak beyond the upper limit or lower limit range of the conditional expression (4), it is difficult to correct aberrations in the lens unit Lis, and aberration fluctuations during image stabilization occur. It gets bigger.

  When the lens group Lis is a lens group having a positive refractive power, it is more preferable to set the numerical range of the conditional expression (4) as follows.

0.25 <| fp / fn | <3.00 (4a)
When the lens group Lis is a lens group having a negative refractive power, it is more preferable to set the numerical range of the conditional expression (4) as follows.

0.3 <| fp / fn | <4.0 (4b)
Conditional expression (5) is the difference between the dispersion of the material constituting the lens ln having the strongest positive refractive power and the dispersion of the material constituting the lens ln having the strongest negative refracting power in the vibration-proof lens group Lis. Is stipulated.

  In order to reduce the variation in chromatic aberration during image stabilization, it is desirable that the chromatic aberration is corrected well in the lens unit Lis in addition to the chromatic aberration corrected in the entire system. If the difference in the dispersion of the materials constituting the lens lp and the lens ln is small beyond the range of the conditional expression (5), the chromatic aberration correction in the lens unit Lis becomes insufficient, and the variation of chromatic aberration particularly during image stabilization becomes large. Come. In particular, when the lens unit Lis is arranged at a position where the absolute value in the conditional expression (2) is large, it is more preferable to set the numerical range of the conditional expression (5) as follows.

10 <| νp−νn | (5a)
Specifically, the value of conditional expression (2) is −0.7 <Dis / DL <−0.3.
Or 0.2 <Dis / DL <0.4 (2b)
In such a case, it is desirable that the conditional expression (5a) is satisfied.

  When the lens unit Lis is arranged at a position that takes the range of the conditional expression (2b), the incident height from the optical axis of the off-axis light beam passing through the lens unit Lis is slightly high, and particularly the lateral chromatic aberration during vibration isolation Fluctuation is likely to occur. Therefore, it is desirable to satisfy the above condition (5a) in order to sufficiently correct the variation of chromatic aberration in the lens unit Lis.

  Conditional expression (6) defines an appropriate range of dispersion values for the material constituting the lens that has the most refractive power of the lens group Lis among the lenses that constitute the vibration-proof lens group Lis. doing. If the Abbe number of the material of the lens having the same refractive power as that of the lens unit Lis exceeds the range of the conditional expression (6), the variation in chromatic aberration during image stabilization increases. come. More preferably, the numerical range of conditional expression (6) is set as follows.

40 <νd (6a)
Conditional expression (7) is the length Tis on the optical axis of the lens group Lis for vibration isolation and the length on the optical axis from the first lens surface (most object side lens surface) to the final lens surface (optical length). An appropriate range is specified for the ratio of DL. If the upper limit of the conditional expression (7) is exceeded and the length of the lens group Lis on the optical axis is too long, the lens group Lis becomes large and the load on the drive mechanism becomes excessive. If the length on the optical axis of the lens unit Lis is too short exceeding the lower limit of the conditional expression (7), the lens shape is difficult to process, which is not good. More preferably, the numerical range of conditional expression (7) is set as follows.

0.04 <Tis / DL <0.20 (7a)
Conditional expression (8) defines a preferable ratio of the total lens length to the focal length of the entire system. If the upper limit of conditional expression (8) is exceeded, the optical system and the lens barrel that holds it will become large, and it will be inconvenient to carry during shooting. On the other hand, if the lower limit of conditional expression (8) is exceeded, it will be difficult to achieve good optical performance while ensuring sufficient back focus. More preferably, the numerical range of conditional expression (8) should be set as follows.

2.5 <TL / f <4.5 (8a)
Next, the lens configuration of each example will be described. In Example 1 of FIG. 1 and Example 2 of FIG. 4, the optical system LA is arranged in order from the object side to the image side, with a front group LF having a negative refractive power and a rear group having a positive refractive power at the widest air interval. It consists of LR.

  The front group LF includes a positive lens, a negative lens, and a negative lens in order from the object side to the image side. The rear group LR sequentially moves from the object side to the image side in a direction having a component perpendicular to the optical axis to move the imaging position in the direction perpendicular to the optical axis, a positive lens, and an aperture stop. A negative lens, a positive lens, and a positive lens. Focusing is performed by moving the entire optical system.

  In Example 3 of FIG. 7, the optical system LA includes, in order from the object side to the image side, a front group LF having a negative refractive power and a rear group LR having a positive refractive power with the widest air gap as a boundary. The front group LF includes a positive lens, a negative lens, a negative lens, and a positive lens in order from the object side to the image side. The rear group LR is a positive lens, an aperture stop, a negative lens, a lens group Lis that moves in a direction having a component perpendicular to the optical axis, and moves an imaging position in a direction perpendicular to the optical axis, a positive lens, Consists of a positive lens. Focusing is performed by moving the entire optical system.

  In Example 4 of FIG. 10, the optical system LA includes, in order from the object side to the image side, a front group LF having a negative refractive power that does not move during focusing and a rear group LR having a positive refractive power that moves during focusing. The front group LF includes a positive lens, a negative lens, and a positive lens in order from the object side to the image side. The rear lens group LR moves in order from the object side to the image side in the direction having a component perpendicular to the optical axis by moving the negative lens, the positive lens, the negative lens, the aperture stop, the positive lens, the negative lens, and the optical axis. The lens unit Lis moves in the direction perpendicular to the optical axis, and includes a positive lens.

  In Example 5 of FIG. 13, the optical system LA includes, in order from the object side to the image side, a front group LF having a negative refractive power and a rear group LR having a positive refractive power with the widest air interval as a boundary. The front group consists of a negative lens in order from the object side to the image side, a lens group Lis that moves in a direction having a component perpendicular to the optical axis, and moves the imaging position in a direction perpendicular to the optical axis. Become. The rear group includes a negative lens, a positive lens, an aperture stop, a positive lens, a negative lens, a positive lens, and a positive lens. Focusing is performed by moving the entire optical system.

  Next, an embodiment of a single-lens reflex camera system (imaging device) using the optical system of the present invention will be described with reference to FIG. In FIG. 16, 10 is a single-lens reflex camera body, and 11 is an interchangeable lens equipped with an optical system according to the present invention. Reference numeral 12 denotes a recording unit such as a film or an image sensor for recording a subject image obtained through the interchangeable lens 11. Reference numeral 13 denotes a finder optical system for observing a subject image from the interchangeable lens 11, and reference numeral 14 denotes a rotating quick return mirror for switching the subject image formed by the interchangeable lens 11 to the recording means 12 and the finder optical system 13 for transmission. is there.

  When observing the subject image with the finder, the subject image formed on the focusing plate 15 via the quick return mirror 14 is made into an erect image with the pentaprism 16 and then magnified and observed with the eyepiece optical system 17. At the time of shooting, the quick return mirror 14 rotates in the direction of the arrow, and the subject image is formed and recorded on the recording means 12. Reference numeral 18 denotes a submirror, and 19 denotes a focus detection device. Thus, by applying the optical system of the present invention to an imaging device such as an interchangeable lens such as a single-lens reflex camera, an imaging device having high optical performance is realized.

  The present invention can be similarly applied to a camera without a quick return mirror. Further, the present invention can be similarly applied to a projection lens for a projector.

  In the following, numerical examples 1 to 5 corresponding to the first to fifth examples will be described. In each numerical example, i indicates the order of the surfaces from the object side, and ri is the i-th (i-th surface) radius of curvature. di is an interval between the i-th surface and the i + 1-th surface. ndi and νdi denote a refractive index and an Abbe number based on the d line, respectively. BF is a back focus. * Indicates that the surface is aspherical. (Aspheric data) shows the aspheric coefficient when the aspheric surface is expressed by the following equation.

x = (h ² / R) / [1+ {1− (1 + k) (h / R) ² } ^1/2 + B · h ⁴ + C · h ⁶ + D · h ⁸ + E · h ¹⁰
However,
x: A displacement amount from the reference plane in the optical axis direction.
h: Height in the direction perpendicular to the optical axis.
R: radius of a quadric surface as a base.

B, C, D, and E are fourth-order, sixth-order, eighth-order, and tenth-order aspherical coefficients, respectively. In addition, the display of “e-Z” means “10 ^−Z ”. Table 1 shows the relationship between the above-described conditional expressions and numerical values in the numerical examples.

(Numerical example 1)
Unit mm
Surface data surface number rd nd νd
1 70.710 2.90 1.51633 64.1
2 152.571 0.20
4 17.124 6.15
5 206.476 1.50 1.51633 64.1
6 19.419 12.79
7 61.632 3.00 1.83481 42.7
8 -44.559 1.40 1.62004 36.3
9 47.336 2.00
10 19.758 4.85 1.65412 39.7
11 -110.713 2.34
12 (Aperture) ∞ 4.00
13 -26.943 2.35 1.80518 25.4
14 45.710 0.70
15 50.202 3.40 1.58913 61.1
16 -60.706 0.79
17 * -174.022 3.15 1.58313 59.4
18 -19.740
Image plane ∞

Aspheric data 17th surface
B = -4.56928e-05 C = 1.05395e-08 D = -9.32716e-10 E = 0.0
Various data focal length 27.70
F number 2.86
Half angle of view ω (degrees) 38.00
Statue height 21.64
Total lens length 91.72
BF 38.70

Anti-vibration lens group (7th to 9th surfaces) data fis 176.80
βis 1.264
βr -0.805
fp 31.38
fn -36.80
νp 42.7
νn 36.3

(Numerical example 2)
Unit mm
Surface data surface number rd nd νd
1 68.237 2.99 1.51633 64.1
2 160.754 0.20
3 52.637 1.50 1.51633 64.1
4 18.406 5.06
5 81.357 1.50 1.58913 61.1
6 18.954 14.34
7 43.097 2.34 1.80 400 46.6
8 -138.167 0.60
9 -226.375 1.00 1.61293 37.0
10 35.059 2.00
11 19.707 5.13 1.65412 39.7
12 -78.719 2.74
13 (Aperture) ∞ 4.00
14 -23.416 1.00 1.80518 25.4
15 48.743 0.92
16 52.996 2.61 1.58913 61.1
17 -47.986 1.99
18 * -139.826 3.09 1.58313 59.4
19 -20.055
Image plane ∞

Aspheric data 18th surface
B = -4.52781e-05 C = -2.25788e-08 D = -6.86526e-10 E = 0.0


Focal length 27.59
F number 2.86
Half angle of view ω (degrees) 38.10
Statue height 21.64
Total lens length 91.85
BF 38.83

Anti-vibration lens group (7th-10th surfaces) data fis 193.69
βis 1.211
βr -0.867
fp 41.10
fn -49.46
νp 46.6
νn 37.0

(Numerical Example 3)
Unit mm
Surface data surface number rd nd νd
1 77.184 3.28 1.51633 64.1
2 230.985 0.10
3 40.584 1.50 1.51633 64.1
4 16.912 6.65
5 137.144 1.50 1.51633 64.1
6 18.110 7.99
7 32.844 3.41 1.83400 37.2
8 -1157.221 9.46
9 48.745 2.82 1.72916 54.7
10 -38.501 0.86
11 (Aperture) ∞ 1.97
12 -27.330 1.60 1.84666 23.8
13 63.253 1.90
14 -60.483 1.76 1.78590 44.2
15 -20.152 1.00 1.62230 53.2
16 464.380 1.20
17 105.809 3.57 1.58913 61.1
18 -23.419 0.20
19 * -112.098 2.29 1.58313 59.4
20 -39.160
Image plane ∞

Aspheric data 19th surface
B = -1.49085e-05 C = 1.57058e-08 D = -4.27129e-10 E = 1.51433e-12
Focal length 28.42
F number 2.86
Half angle of view ω (degrees) 37.28
Statue height 21.64
Total lens length 90.84
BF 37.80

Anti-vibration lens group (14th to 16th surfaces) data fis -163.07
βis 0.596
βr -0.543
fp 37.73
fn -31.01
νp 44.2
νn 53.2

(Numerical example 4)
Unit mm
Surface data surface number rd nd νd
1 66.998 3.75 1.48749 70.2
2 197.486 0.10
3 40.664 2.00 1.65 160 58.5
4 17.649 4.64
5 46.839 2.60 1.77250 49.6
6 100.511 3.13
7 26.865 1.60 1.65 160 58.5
8 9.583 3.59
9 81.025 2.50 1.84666 23.8
10 554.320 0.21
11 42.536 7.90 1.84666 23.8
12 34.328 1.57
13 (Aperture) ∞ 2.50
14 74.525 3.75 1.79952 42.2
15 -17.110 2.04
16 -31.690 1.60 1.80518 25.4
17 63.141 1.08
18 * 136.755 3.60 1.63930 44.9
19 -18.630 1.20 1.80000 29.8
20 -51.939 1.45
21 * -53.318 3.20 1.67790 55.3
22 -18.616
Image plane ∞

Aspheric data 18th surface
B = 3.12785e-06 C = -6.65485e-08 D = 5.91710e-10 E = -1.60210e-12

21st page
B = -2.73568e-05 C = 3.68829e-08 D = -3.83418e-10 E = 0.0

Focal length 24.50
F number 2.86
Half angle of view ω (degrees) 41.45
Statue height 21.64
Total lens length 91.91
BF 37.90

Anti-vibration lens group (18th-20th surfaces) data Focal length
fis 87.55
βis -3.614
βr 0.093
fp 25.88
fn -36.91
νp 44.9
νn 29.8

(Numerical example 5)
Unit mm
Surface number rd nd νd
1 * 40.777 1.80 1.65 100 56.2
2 18.414 8.03
3 * 41.792 1.20 1.83400 37.2
4 24.123 5.40 1.51633 64.1
5 -245.518 1.00
6 16.493 1.24 1.62041 60.3
7 9.902 9.00
8 -39.271 1.60 1.51633 64.1
9 53.179 0.20
10 26.595 3.40 1.84666 23.8
11 189.806 2.71
12 (Aperture) ∞ 1.00
13 39.449 3.74 1.69680 55.5
14 -23.883 3.66
15 -18.260 1.80 1.84666 23.8
16 61.382 0.42
17 180.550 3.17 1.69680 55.5
18 -19.247 0.54
19 * -28.376 2.00 1.72916 54.7
20 -19.797
Image plane ∞

Aspheric data 1st surface
B = 3.10251e-06 C = -5.18081e-09 D = 1.06929e-11 E = -5.02984e-15

Third side
B = 1.85875e-06 C = 6.78623e-09 D = -6.34644e-12 E = 0.0

19th page
B = -3.02320e-05 C = 8.08892e-08 D = -2.62288e-09 E = 1.22172e-11


Focal length 23.50
F number 2.86
Half angle of view ω (degrees) 42.63
Statue height 21.64
Total lens length 89.80
BF 37.90

Anti-vibration lens group (3rd to 5th surfaces) data fis 111.32
βis 2.186
βr -0.202
fp 42.83
fn -70.60
νp 64.1
νn 37.2

LA optical system L1 1st lens group L2 2nd lens group Gis Anti-vibration lens group SP Aperture stop

Claims (12)

In an optical system whose focal length is shorter than the back focus, the optical system moves in a direction having a component perpendicular to the aperture stop and the optical axis to move the imaging position in the direction perpendicular to the optical axis. The lens group Lis includes one or more of a positive lens and a negative lens, the focal length of the entire system is f, the focal length of the lens group Lis is fis, When the length on the optical axis from the aperture stop of the lens unit Lis to the farthest lens surface is Dis, and the length on the optical axis from the most object side lens surface to the most image side lens surface is DL,
0.08 <f / | fis | <0.50
-0.7 <Dis / DL <0.4
An optical system that satisfies the following conditional expression: When the lateral magnification of the lens group Lis is βis, and the lateral magnification βr of the lens component located on the image side of the lens group Lis,
0.1 <| (1-βis) βr | <0.7
The optical system according to claim 1, wherein the following conditional expression is satisfied. When the focal length of the lens lp having the strongest positive refractive power in the lens group Lis is fp and the focal length of the lens ln having the strongest negative refractive power in the lens group Lis is fn,
0.25 <| fp / fn | <4.00
The optical system according to claim 1, wherein the following conditional expression is satisfied. When the Abbe number of the material of the lens lp having the strongest positive refractive power in the lens group Lis is νp, and the Abbe number of the material of the lens ln having the strongest negative refractive power in the lens group Lis is νn. ,
5 <| νp−νn |
The optical system according to claim 1, wherein the following conditional expression is satisfied. Of the lens lp having the largest positive refractive power in the lens group Lis or the lens ln having the largest negative refractive power in the lens group Lis, the lens material having the same sign as the refractive power of the lens group Lis. When Abbe number is νis,
35 <νis
5. The optical system according to claim 1, wherein the following conditional expression is satisfied. When the length of the lens group Lis on the optical axis is Tis,
0.03 <Tis / DL <0.30
The optical system according to claim 1, wherein the following conditional expression is satisfied. When the length on the optical axis from the lens surface closest to the object side to the image plane is TL,
2.0 <TL / f <5.0
The optical system according to claim 1, wherein the following conditional expression is satisfied.   The optical system according to claim 1, wherein the lens group Lis includes a positive lens and a negative lens.   The optical system includes, in order from the object side to the image side, a front group having a negative refractive power and a rear group having a positive refractive power, with the widest air interval as a boundary, and the front group includes a plurality of lenses. The optical system according to any one of claims 1 to 8, wherein the rear group includes the lens group Lis, a plurality of lenses, and the aperture stop. The optical system comprises, in order from the object side to the image side, a front group of negative refractive power that does not move during focusing and a rear group of positive refractive power that moves during focusing,
The optical system according to any one of claims 1 to 8, wherein the front group includes a plurality of lenses, and the rear group includes the lens group Lis, a plurality of lenses, and the aperture stop. The optical system, in order from the object side to the image side, consists of a front group of negative refractive power and a rear group of positive refractive power, with the widest air interval as a boundary
The optical system according to any one of claims 1 to 8, wherein the front group includes the lens group Lis and a plurality of lenses, and the rear group includes a plurality of lenses and the aperture stop.   An imaging apparatus comprising the optical system according to claim 1.