JP6354257B2 - Variable magnification optical system and imaging apparatus - Google Patents

Description

The present invention relates to a variable magnification optical system and an imaging equipment.

  Conventionally, a variable magnification optical system suitable for a photographic camera, an electronic still camera, a video camera, and the like has been proposed (see, for example, Patent Document 1).

JP-A-63-298210

  In recent years, a variable magnification optical system having better optical performance has been demanded.

The present invention has been made in view of such problems, and an object thereof is to provide a variable power optical system and an imaging equipment having a good optical performance.

In order to achieve such an object, a variable magnification optical system according to the present invention includes a first lens group having a positive refractive power, a second lens group having a negative refractive power, arranged in order from the object side, A third lens group having a positive refractive power, and at least a part of the third lens group has a component in a direction perpendicular to the optical axis as a vibration-proof lens group for correcting image blur. It is configured to be movable and satisfies the following conditional expression.

0.60 <f3 / fw <3.50
4.76 <f1 / f3 <30.00
However,
f1: the focal length of the first lens group,
f3: focal length of the third lens group,
fw: focal length of the entire system in the wide-angle end state.

  An imaging apparatus according to the present invention includes any one of the above-described variable magnification optical systems.

According to the present invention, it is possible to provide a variable power optical system and an imaging equipment having a good optical performance.

It is sectional drawing which shows the lens structure of the variable magnification optical system which concerns on 1st Example. FIG. 4A is an aberration diagram in the wide-angle end state (f = 18.50) of the variable magnification optical system according to the first example. FIG. 5A is a diagram illustrating various aberrations at the time of focusing on infinity, and FIG. (C) is a coma aberration diagram when the zoom lens is performed (shift amount of the anti-vibration lens group = 0.2 mm), and (c) is a graph showing various aberrations when focusing at a short distance (imaging magnification β = −0.009). FIG. 6A is an aberration diagram in the intermediate focal length state (f = 34.95) of the variable magnification optical system according to the first example. FIG. 5A is a diagram illustrating various aberrations at the time of focusing on infinity, and FIG. A coma aberration diagram when correction is performed (shift amount of the image stabilizing lens group = 0.2 mm), and (c) shows various aberration diagrams when focusing at a short distance (imaging magnification β = −0.018). FIG. 5A is an aberration diagram in the telephoto end state (f = 53.50) of the zoom optical system according to the first example. FIG. 5A is a diagram illustrating various aberrations at the time of focusing on infinity, and FIG. (C) is a coma aberration diagram at the time of performing the image stabilization (shift amount of the anti-vibration lens group = 0.2 mm), and FIG. It is sectional drawing which shows the lens structure of the variable magnification optical system which concerns on 2nd Example. FIG. 9A is an aberration diagram in the wide-angle end state (f = 18.74) of the variable magnification optical system according to the second example. FIG. 9A is a diagram illustrating various aberrations at the time of focusing on infinity, and FIG. (C) is a coma aberration diagram when the zoom lens is used (shift amount of the image stabilizing lens group = 0.2 mm), and (c) is a graph showing various aberrations when focusing at a short distance (photographing magnification β = −0.010). FIG. 6A is an aberration diagram in the intermediate focal length state (f = 34.50) of the variable magnification optical system according to the second example. FIG. 5A is an aberration diagram at the time of focusing on infinity, and FIG. A coma aberration diagram when correction is performed (shift amount of the image stabilizing lens group = 0.2 mm), and (c) shows various aberration diagrams when focusing at a short distance (imaging magnification β = −0.018). FIG. 8A is an aberration diagram in the telephoto end state (f = 52.08) of the variable magnification optical system according to Example 2; (a) various aberration diagrams when focusing on infinity; and (b) is image blur correction when focusing on infinity. (C) is a coma aberration diagram when the image stabilization is performed (shift amount of the anti-vibration lens group = 0.2 mm), and (c) is an aberration diagram when focusing at a short distance (imaging magnification β = −0.026). It is sectional drawing which shows the lens structure of the variable magnification optical system which concerns on 3rd Example. FIG. 10 is an aberration diagram in the wide-angle end state (f = 18.72) of the variable magnification optical system according to Example 3, (a) Various aberration diagrams when focusing on infinity, and (b) Image blur correction when focusing on infinity. (C) is a coma aberration diagram when the zoom lens is used (shift amount of the image stabilizing lens group = 0.2 mm), and (c) is a graph showing various aberrations when focusing at a short distance (photographing magnification β = −0.010). FIG. 10A is an aberration diagram in the intermediate focal length state (f = 35.50) of the variable magnification optical system according to the third example. FIG. 10A is a diagram illustrating aberrations at the time of focusing on infinity, and FIG. A coma aberration diagram when correction is performed (shift amount of the image stabilizing lens group = 0.2 mm), and (c) shows various aberration diagrams when focusing at a short distance (imaging magnification β = −0.018). FIG. 6A is an aberration diagram in the telephoto end state (f = 52.00) of the zoom optical system according to Example 3; FIG. 5A is a diagram illustrating various aberrations at the time of focusing on infinity, and FIG. (C) is a coma aberration diagram at the time of performing the image stabilization (shift amount of the anti-vibration lens group = 0.2 mm), and FIG. It is a schematic sectional drawing which shows the structure of the camera which concerns on this embodiment. It is a flowchart for demonstrating the manufacturing method of the variable magnification optical system which concerns on this embodiment.

  Hereinafter, the present embodiment will be described with reference to the drawings. As shown in FIG. 1, the variable magnification optical system ZL according to this embodiment includes a first lens group G1 having a positive refractive power and a second lens group G2 having a negative refractive power, which are arranged in order from the object side. And a third lens group G3 having a positive refractive power.

  With this configuration, it is possible to satisfactorily correct aberration reduction during zooming and zooming.

  Further, the variable magnification optical system ZL uses at least a part of the third lens group G3 (for example, a positive meniscus lens L34 having a convex surface facing the object side in FIG. 1) as an anti-vibration lens group for correcting image blur. It is configured to be movable so as to have a component perpendicular to the optical axis.

  With this configuration, it is possible to simultaneously correct fluctuations in the curvature of field during image blur correction and fluctuations in decentering coma.

  Under the above configuration, the variable magnification optical system ZL satisfies the following conditional expression (1).

0.60 <f3 / fw <3.50 (1)
However,
f3: focal length of the third lens group G3,
fw: focal length of the entire system in the wide-angle end state.

  Conditional expression (1) defines the ratio between the focal length f3 of the third lens group G3 and the focal length fw of the entire system in the wide-angle end state. The zooming optical system ZL can satisfy the conditional expression (1), thereby realizing downsizing of the lens barrel and good optical performance.

  When the upper limit of conditional expression (1) is exceeded, the refractive power of the third lens group G3 becomes weak, and it becomes difficult to reduce the size of the lens barrel. In order to reduce the size, the refractive power of the first lens group G1 and the second lens group G2 is increased, and it becomes difficult to correct coma, astigmatism, and field curvature. If the lower limit of conditional expression (1) is not reached, the refractive power of the third lens group G3 becomes strong, and it becomes difficult to correct spherical aberration, coma aberration, and astigmatism.

  By setting the lower limit of conditional expression (1) to 0.75, better aberration correction can be performed. By setting the lower limit value of conditional expression (1) to 0.85, even better aberration correction can be achieved.

  By setting the upper limit of conditional expression (1) to 2.00, better aberration correction becomes possible. By setting the upper limit value of the conditional expression (1) to 1.50, it becomes possible to correct aberrations even better.

  The variable magnification optical system ZL according to the present embodiment changes the air gap between the first lens group G1 and the second lens group G2 and the air gap between the second lens group G2 and the third lens group G3. It is preferable to perform zooming.

  With this configuration, it is possible to satisfactorily correct spherical aberration and field curvature that occur during zooming.

  The zoom optical system ZL according to the present embodiment enlarges the air gap between the first lens group G1 and the second lens group G2 during zooming from the wide-angle end state to the telephoto end state, and the second lens group G2. It is preferable to reduce the distance from the third lens group G3.

  With this configuration, it is possible to satisfactorily correct spherical aberration and field curvature that occur during zooming.

  The zoom optical system ZL according to the present embodiment preferably satisfies the following conditional expression (2).

4.70 <f1 / f3 <30.00 (2)
However,
f1: Focal length of the first lens group G1.

  Conditional expression (2) defines the ratio between the focal length f1 of the first lens group G1 and the focal length f3 of the third lens group G3. The zooming optical system ZL can satisfy the conditional expression (2), thereby realizing downsizing of the lens barrel and a predetermined zooming ratio.

  If the upper limit value of conditional expression (2) is exceeded, the refractive power of the third lens group G3 becomes strong, and it becomes difficult to correct spherical aberration and coma aberration in the telephoto end state. If the lower limit of conditional expression (2) is not reached, the refractive power of the first lens group G1 becomes strong, and it becomes difficult to correct coma, astigmatism, and field curvature in the telephoto end state.

  By setting the lower limit of conditional expression (2) to 4.76, better aberration correction becomes possible.

  By setting the upper limit of conditional expression (2) to 10.00, better aberration correction becomes possible.

  The zoom optical system ZL according to the present embodiment preferably satisfies the following conditional expression (3).

0.60 <(− f2) / f3 <1.05 (3)
However,
f2: focal length of the second lens group G2.

  Conditional expression (3) defines the ratio between the focal length f3 of the third lens group G3 and the focal length f2 of the second lens group G2. The zooming optical system ZL can achieve good optical performance and a predetermined zooming ratio by satisfying conditional expression (3).

  If the upper limit of conditional expression (3) is exceeded, the refractive power of the third lens group G3 becomes strong, and it becomes difficult to correct spherical aberration and coma aberration in the telephoto end state. If the lower limit of conditional expression (3) is not reached, the refractive power of the second lens group G2 becomes strong, and it becomes difficult to correct coma and astigmatism in the wide-angle end state.

  By setting the lower limit of conditional expression (3) to 0.70, better aberration correction can be performed.

  By setting the upper limit of conditional expression (3) to 1.00, better aberration correction becomes possible.

  The variable magnification optical system ZL according to the present embodiment preferably satisfies the following conditional expression (4).

5.20 <f1 / (− f2) <30.00 (4)
However,
f1: Focal length of the first lens group G1
f2: focal length of the second lens group G2.

  Conditional expression (4) defines the ratio between the focal length f1 of the first lens group G1 and the focal length f2 of the second lens group G2. The zooming optical system ZL can achieve good optical performance and a predetermined zooming ratio by satisfying conditional expression (4).

  If the upper limit of conditional expression (4) is exceeded, the refractive power of the second lens group G2 will become strong, and it will be difficult to correct coma and astigmatism in the wide-angle end state. If the lower limit of conditional expression (4) is not reached, the refractive power of the first lens group G1 becomes strong, and it becomes difficult to correct coma, astigmatism, and field curvature in the telephoto end state.

  By setting the lower limit of conditional expression (4) to 5.30, better aberration correction becomes possible.

  By setting the upper limit of conditional expression (4) to 10.00, better aberration correction becomes possible.

  In the zoom optical system ZL according to the present embodiment, it is preferable to perform focusing by moving at least a part of the third lens group G3 (for example, the biconvex lens L31 in FIG. 1) along the optical axis direction. .

  With this configuration, it is possible to satisfactorily correct the downsizing of the lens barrel and aberration fluctuations during focusing (for example, spherical aberration, curvature of field, etc.).

  In the zoom optical system ZL according to this embodiment, it is preferable that the first lens group G1 includes one cemented lens.

  With this configuration, it is possible to satisfactorily correct lateral chromatic aberration in the telephoto end state while reducing the size of the lens barrel.

  In the variable magnification optical system ZL according to the present embodiment, it is preferable that the second lens group G2 includes two negative lenses and one positive lens.

  With this configuration, coma aberration and field curvature in the wide-angle end state can be corrected well.

  In the zoom optical system ZL according to the present embodiment, it is preferable that the second lens group G2 includes a negative lens, a negative lens, and a positive lens arranged in order from the object side.

  With this configuration, coma aberration and field curvature in the wide-angle end state can be corrected well.

  In the zoom optical system ZL according to this embodiment, it is preferable that the third lens group G3 includes six or more lenses.

  With this configuration, spherical aberration and coma can be favorably corrected.

  The variable magnification optical system ZL according to the present embodiment preferably satisfies the following conditional expression (5).

30.00 ° <ωw <80.00 ° (5)
However,
ωw: Half angle of view in the wide angle end state.

  Conditional expression (5) is a condition that defines the value of the angle of view in the wide-angle end state. By satisfying this conditional expression (5), coma aberration, distortion aberration, and field curvature can be favorably corrected while having a wide angle of view.

  By setting the lower limit of conditional expression (5) to 33.00 °, better aberration correction can be performed. By setting the lower limit value of conditional expression (5) to 36.00 °, it becomes possible to perform better aberration correction.

  By setting the upper limit of conditional expression (5) to 77.00 °, better aberration correction can be performed.

  The zoom optical system ZL according to the present embodiment preferably satisfies the following conditional expression (6).

2.00 <ft / fw <15.00 (6)
However,
ft: focal length of the entire system in the telephoto end state.

  Conditional expression (6) is a condition that defines the ratio between the focal length of the entire system in the telephoto end state and the focal length of the entire system in the wide-angle end state. The present variable magnification optical system ZL can obtain a high zoom ratio by satisfying conditional expression (6), and can satisfactorily correct spherical aberration and coma.

  By setting the lower limit of conditional expression (6) to 2.30, better aberration correction becomes possible. By setting the lower limit value of conditional expression (6) to 2.50, better aberration correction can be achieved. By setting the lower limit of conditional expression (6) to 2.70, the effect of the present embodiment can be maximized.

  By setting the upper limit of conditional expression (6) to 10.00, better aberration correction becomes possible. By setting the upper limit value of conditional expression (6) to 7.00, even better aberration correction can be achieved.

  According to the present embodiment as described above, a variable magnification optical system ZL having good optical performance can be realized.

  Next, a camera (imaging device) 1 including the above-described variable magnification optical system ZL will be described with reference to FIG. As shown in FIG. 13, the camera 1 is an interchangeable lens camera (so-called mirrorless camera) provided with the above-described variable magnification optical system ZL as the photographing lens 2.

  In the camera 1, light from an object (subject) (not shown) is collected by the photographing lens 2, and the subject is placed on the imaging surface of the imaging unit 3 via an OLPF (Optical low pass filter) not shown. Form an image. Then, the subject image is photoelectrically converted by the photoelectric conversion element provided in the imaging unit 3 to generate an image of the subject. This image is displayed on an EVF (Electronic view finder) 4 provided in the camera 1. Thus, the photographer can observe the subject via the EVF 4.

  When the release button (not shown) is pressed by the photographer, the subject image generated by the imaging unit 3 is stored in a memory (not shown). In this way, the photographer can shoot the subject with the camera 1.

  The variable magnification optical system ZL according to this embodiment mounted on the camera 1 as the photographing lens 2 has good optical performance due to its characteristic lens configuration, as can be seen from each example described later. Therefore, according to the present camera 1, it is possible to realize an imaging device having good optical performance.

  Even when the above-described variable magnification optical system ZL is mounted on a single-lens reflex camera that has a quick return mirror and observes a subject with a finder optical system, the same effect as the camera 1 can be obtained. Further, even when the above-described variable magnification optical system ZL is mounted on a video camera, the same effects as the camera 1 can be obtained.

  Next, an outline of a method for manufacturing the variable magnification optical system ZL having the above configuration will be described with reference to FIG. First, a first lens group G1 having a positive refractive power, a second lens group G2 having a negative refractive power, and a third lens having a positive refractive power, which are arranged in order from the object side in the lens barrel. Each lens is arranged so as to have the group G3 (step ST10). At this time, at least a part of the third lens group G3 is configured as a vibration-proof lens group for correcting image blur so as to be movable so as to have a component perpendicular to the optical axis (step ST20). Each lens is arranged in the lens barrel so as to satisfy the following conditional expression (1) (step ST30).

0.60 <f3 / fw <3.50 (1)
However,
f3: focal length of the third lens group G3,
fw: focal length of the entire system in the wide-angle end state.

  As an example of the lens arrangement in the present embodiment, as shown in FIG. 1, as the first lens group G1, in order from the object side, a negative meniscus lens L11 having a convex surface facing the object side and a biconvex lens L12 are joined positively. Place the lens. As the second lens group G2, a negative meniscus lens L21 having a convex surface directed toward the object side, a biconcave lens L22, and a positive meniscus lens L23 having a convex surface directed toward the object side are disposed in order from the object side. As the third lens group G3, in order from the object side, a biconvex lens L31, a cemented positive lens composed of a biconvex lens L32 and a biconcave lens L33, a positive meniscus lens L34 having a convex surface facing the object side, a biconvex lens L35, and an image. A negative meniscus lens L36 having a convex surface on the side is disposed. Further, each lens is arranged so as to satisfy the conditional expression (1) (the corresponding value of the conditional expression (1) is 1.14).

  According to the method for manufacturing a variable magnification optical system according to the present embodiment as described above, a variable magnification optical system ZL having good optical performance can be obtained.

  Hereinafter, each example according to the present embodiment will be described with reference to the drawings. Tables 1 to 3 are shown below, but these are tables of specifications in the first to third examples.

  1, FIG. 5 and FIG. 9 are cross-sectional views showing a configuration of a variable magnification optical system ZL (ZL1 to ZL3) according to each example. In the cross-sectional views of the zoom optical systems ZL1 to ZL3, the movement trajectory along the optical axis of each lens group G1 to G3 when zooming from the wide-angle end state (W) to the telephoto end state (T) is indicated by an arrow. .

  Each reference code for FIG. 1 according to the first embodiment is used independently for each embodiment in order to avoid complication of explanation due to an increase in the number of digits of the reference code. Therefore, even if the same reference numerals as those in the drawings according to the other embodiments are given, they are not necessarily in the same configuration as the other embodiments.

  In each embodiment, d-line (wavelength 587.5620 nm) and g-line (wavelength 435.8350 nm) are selected as the calculation targets of the aberration characteristics.

  In [Lens data] in the table, the surface number is the order of the optical surfaces from the object side along the traveling direction of the light beam, r is the radius of curvature of each optical surface, D is the next optical surface (or The distance between the surfaces on the optical axis to the image plane), νd is the Abbe number based on the d-line of the material of the optical member, and nd is the refractive index of the material of the optical member with respect to the d-line. (Variable) indicates a variable surface interval, “∞” of the radius of curvature indicates a plane or an aperture, and (aperture S) indicates an aperture aperture S. The refractive index of air (d-line) “1.00000” is omitted. When the optical surface is an aspherical surface, “*” is attached to the left side of the surface number, and the paraxial radius of curvature is indicated in the column of the radius of curvature R.

In [Aspherical data] in the table, the shape of the aspherical surface shown in [Lens data] is shown by the following equation (a). Here, y is the height in the direction perpendicular to the optical axis, X (y) is the amount of displacement (sag amount) in the optical axis direction at height y, r is the radius of curvature of the reference sphere (paraxial radius of curvature), κ Denotes a conic constant, and An denotes an nth-order aspheric coefficient. Incidentally, "E-n" denotes "× 10 ^-n", for example "1.234E-05" denotes "1.234 × 10 ^-5".

X (y) = (y ² / r) / [1+ {1−κ (y ² / r ² )} ^1/2 ] + A 4 × y ⁴ + A 6 × y ⁶ + A 8 × y ⁸ + A 10 × y ¹⁰ (a)

  In [Various data] in the table, f is the focal length of the entire lens system, Fno is the F number, ω is the half angle of view (unit: °), Y is the image height, TL is the total length of the lens system (on the optical axis) Bf represents the back focus (distance from the last lens surface to the image plane I on the optical axis).

  In [Variable interval data] in the table, the focal length of the entire system in the wide-angle end state, the intermediate focal length state, and the telephoto end state at the time of focusing on an object at infinity and a short distance object (shooting distance R = 2.0 m) f or photographing magnification β and the value of each variable interval are shown. D0 is the distance from the object surface to the first surface, Di (where i is an integer) is the variable distance between the i-th surface and the (i + 1) -th surface, and Bf is the back focus.

  In [Lens Group Data] in the table, the first surface of each group shows the start surface number (most surface number on the object side) of each group, and the focal length of each group shows the group focal length.

  In [Values for Conditional Expressions] in the table, values corresponding to the conditional expressions (1) to (6) are shown.

  Hereinafter, in all the specification values, “mm” is generally used for the focal length f, the radius of curvature r, the surface interval D, and other lengths, etc. unless otherwise specified, but the optical system is proportionally enlarged. Alternatively, the same optical performance can be obtained even by proportional reduction, and the present invention is not limited to this. Further, the unit is not limited to “mm”, and other appropriate units can be used.

  The description of the table so far is common to all the embodiments, and the description below is omitted.

(First embodiment)
A first embodiment will be described with reference to FIGS. As shown in FIG. 1, the variable magnification optical system ZL (ZL1) according to the first example includes a first lens group G1 having a positive refractive power arranged in order from the object side along the optical axis, and a negative lens group G1. It is composed of a second lens group G2 having a refractive power and a third lens group G3 having a positive refractive power.

  The first lens group G1 is composed of a cemented positive lens composed of a negative meniscus lens L11 and a biconvex lens L12 arranged in order from the object side and having a convex surface directed toward the object side.

  The second lens group G2 includes a negative meniscus lens L21 having a convex surface facing the object side, a biconcave lens L22, and a positive meniscus lens L23 having a convex surface facing the object side, which are arranged in order from the object side. The object side surface of the negative meniscus lens L21 is aspheric.

  The third lens group G3 includes, in order from the object side, a biconvex lens L31, a cemented positive lens of the biconvex lens L32 and the biconcave lens L33, a positive meniscus lens L34 having a convex surface facing the object side, and a biconvex lens L35. And a negative meniscus lens L36 having a convex surface facing the image side.

  An aperture stop S that determines the F number is provided in the third lens group G3.

  The image plane I is formed on an image sensor (not shown), and the image sensor is composed of a CCD, a CMOS, or the like.

  The variable magnification optical system ZL1 according to the first example changes the air gap between the first lens group G1 and the second lens group G2 and the air gap between the second lens group G2 and the third lens group G3. Thus, zooming from the wide-angle end state to the telephoto end state is performed. At this time, the first lens group G1 to the third lens group G3 move toward the object side with respect to the image plane I. The aperture stop S moves to the object side together with the third lens group G3 during zooming.

  Specifically, in the zoom optical system ZL1 according to the first example, the air distance between the first lens group G1 and the second lens group G2 is increased, and the air between the second lens group G2 and the third lens group G3 is increased. Zooming from the wide-angle end state to the telephoto end state is performed by moving the lens groups G1 to G3 along the optical axis so that the interval is reduced.

  The variable magnification optical system ZL1 according to the first example is configured to perform focusing by moving the biconvex lens L31 of the third lens group G3 along the optical axis direction. As shown by the arrows in FIG. When the state of focusing on an object at infinity is changed to the state of focusing on an object at a short distance, the biconvex lens L31 moves from the object side to the image side.

  When image blurring occurs, a positive meniscus lens L34 having a convex surface facing the object side of the third lens group G3 is moved as an anti-vibration lens group so as to have a component in a direction perpendicular to the optical axis. Perform image blur correction (anti-vibration).

  Table 1 below shows the values of each item in the first example. Surface numbers 1 to 21 in Table 1 correspond to the optical surfaces m1 to m21 shown in FIG.

(Table 1)
[Lens data]
Surface number r D νd nd
1 73.1346 1.6000 23.80 1.84666
2 47.7461 4.4680 55.52 1.69680
3 -2795.9453 D3 (variable)
* 4 86.1349 1.3000 46.60 1.80400
5 11.7958 6.0000
6 -86.9238 1.0000 46.60 1.80400
7 38.6168 0.1000
8 20.8772 3.0000 23.80 1.84666
9 111.9344 D9 (variable)
10 32.7034 2.2000 55.35 1.67790
11 -64.0118 D11 (variable)
12 ∞ 0.5000 (Aperture S)
13 9.7190 3.1000 61.22 1.58913
14 -45.7099 1.1044 29.37 1.95000
15 14.5899 5.0000
16 30.0000 1.5000 31.27 1.90366
17 200.0000 3.0000
18 296.9316 2.1000 50.27 1.71999
19 -22.1475 1.6841
20 -9.9417 1.1000 46.60 1.80400
21 -24.7454 Bf (variable)

[Aspherical data]
4th surface κ = 1.0000
A4 = -1.68932E-06
A6 = 3.45601E-09
A8 = 3.25066E-11
A10 = -1.38349E-13

[Various data]
f 18.50-53.50
Fno 3.62 to 5.91
ω 39.30 〜 14.42
Y 14.25-14.25
TL 80.892 to 108.569
Bf 18.519-37.340

[Variable interval data]
(Infinity) (shooting distance 2m)
Wide-angle end Medium telephoto end Wide-angle end Medium telephoto end
f, β 18.503 34.953 53.500 -0.009 -0.018 -0.027
D0 0.000 0.000 0.000 1918.427 1909.008 1890.749
D3 1.000 9.986 25.233 1.000 9.986 25.233
D9 17.878 6.525 2.500 18.261 6.878 3.013
D11 4.739 4.739 4.739 4.356 4.387 4.226
Bf 18.519 30.304 37.340 18.519 30.304 37.340

[Lens group data]
Group number Group first surface Group focal length G1 1 114.802
G2 4 -18.462
G3 10 21.087

[Conditional expression values]
Conditional expression (1): f3 / fw = 1.14
Conditional expression (2): f1 / f3 = 5.44
Conditional expression (3): f2 / (− f3) = 0.88
Conditional expression (4): f1 / (− f2) = 6.22
Conditional expression (5): ωw = 39.30
Conditional expression (6): ft / fw = 2.89

  From Table 1, it is understood that the variable magnification optical system ZL1 according to the first example satisfies the conditional expressions (1) to (6).

  2A and 2B are aberration diagrams in the wide-angle end state (f = 18.50) of the variable magnification optical system ZL1 according to the first example. FIG. 2A is a diagram illustrating various aberrations at the time of focusing on infinity, and FIG. A coma aberration diagram when the image blur correction is performed at the time of focusing (shift amount of the anti-vibration lens group = 0.2 mm), and (c) shows various aberration diagrams at the time of focusing at a short distance (imaging magnification β = −0.009). FIG. 3 is an aberration diagram in the intermediate focal length state (f = 34.95) of the variable magnification optical system ZL1 according to the first example, (a) various aberration diagrams at the time of focusing on infinity, and (b) at infinity. Coma aberration diagram when image blur correction is performed at the time of focus (shift amount of anti-vibration lens group = 0.2 mm), (c) shows various aberration diagrams at the time of focusing at close distance (shooting magnification β = -0.018). . 4A and 4B are aberration diagrams in the telephoto end state (f = 53.50) of the variable magnification optical system ZL1 according to the first example. FIG. 4A is a diagram illustrating various aberrations at the time of focusing on infinity, and FIG. A coma aberration diagram when image blur correction is performed at the time of focus (shift amount of the anti-vibration lens group = 0.2 mm), and (c) shows various aberration diagrams when focusing at a short distance (photographing magnification β = −0.027). In this embodiment, the optical performance at the time of image stabilization is shown in FIG. 2 (b), FIG. 3 (b) and FIG. 4 (b). A coma aberration diagram corresponding to is shown.

  In each aberration diagram, FNO is the F number, Y is the image height, d is the aberration at the d-line, and g is the aberration at the g-line. Those without d and g indicate aberration at the d-line. In the spherical aberration diagram, the F-number value corresponding to the maximum aperture is shown, and in the astigmatism diagram and the distortion diagram, the maximum image height is shown. In the astigmatism diagram, the solid line indicates the sagittal image plane, and the broken line indicates the meridional image plane. In the coma aberration diagram, a solid line indicates a meridional coma, and a broken line indicates a sagittal coma. The explanation of the above aberration diagrams is the same in the other examples, and the explanation is omitted.

  2 to 4, it can be seen that the variable magnification optical system ZL1 according to the first example has excellent imaging performance with various aberrations corrected well from the wide-angle end state to the telephoto end state. . It can also be seen that the image forming performance is high even when image blur correction is performed.

(Second embodiment)
A second embodiment will be described with reference to FIGS. As shown in FIG. 5, the variable magnification optical system ZL (ZL2) according to the second example includes a first lens group G1 having a positive refractive power and arranged in order from the object side along the optical axis. It is composed of a second lens group G2 having a refractive power and a third lens group G3 having a positive refractive power.

  The first lens group G1 is composed of a cemented positive lens that is arranged in order from the object side and includes a negative meniscus lens L11 having a convex surface facing the object side and a positive meniscus lens L12 having a convex surface facing the object side.

  The second lens group G2 includes a negative meniscus lens L21 having a convex surface facing the object side, a biconcave lens L22, and a positive meniscus lens L23 having a convex surface facing the object side, which are arranged in order from the object side. The object side surface of the negative meniscus lens L21 is aspheric.

  The third lens group G3 includes a positive meniscus lens L31 having a convex surface directed toward the object side, a cemented positive lens formed by a biconvex lens L32 and a negative meniscus lens L33, and a negative lens having a convex surface directed toward the object side. It comprises a meniscus lens L34, a biconvex lens L35, and a negative meniscus lens L36 having a convex surface facing the image side. The image side surface of the negative meniscus lens L36 is aspheric.

  An aperture stop S that determines the F number is provided in the third lens group G3.

  The image plane I is formed on an image sensor (not shown), and the image sensor is composed of a CCD, a CMOS, or the like.

  The variable magnification optical system ZL2 according to the second example changes the air gap between the first lens group G1 and the second lens group G2 and the air gap between the second lens group G2 and the third lens group G3. Thus, zooming from the wide-angle end state to the telephoto end state is performed. At this time, the first lens group G1 to the third lens group G3 move toward the object side with respect to the image plane I. The aperture stop S moves to the object side together with the third lens group G3 during zooming.

  Specifically, in the zoom optical system ZL2 according to the second example, the air gap between the first lens group G1 and the second lens group G2 is increased, and the air between the second lens group G2 and the third lens group G3 is increased. Zooming from the wide-angle end state to the telephoto end state is performed by moving the lens groups G1 to G3 along the optical axis so that the interval is reduced.

  The variable magnification optical system ZL2 according to the second example is configured to perform focusing by moving a positive meniscus lens L31 having a convex surface toward the object side of the third lens group G3 along the optical axis direction. As indicated by the arrow 5, the positive meniscus lens L <b> 31 moves from the object side to the image side when the state is changed from focusing on an object at infinity to focusing on a near object.

  When an image blur occurs, the negative positive meniscus lens L34 having a convex surface facing the object side of the third lens group G3 is moved as an anti-vibration lens group so as to have a component perpendicular to the optical axis. Image blur correction (anti-vibration).

  Table 2 below shows the values of each item in the second embodiment. Surface numbers 1 to 21 in Table 2 correspond to the optical surfaces m1 to m21 shown in FIG.

(Table 2)
[Lens data]
Surface number r D νd nd
1 53.5681 1.6000 23.80 1.84666
2 37.0346 5.7211 55.52 1.69680
3 353.3821 D3 (variable)
* 4 45.0000 1.2492 46.60 1.80400
5 12.0000 4.6255
6 -419.8499 1.0000 46.60 1.80400
7 16.0327 2.2223
8 17.7685 3.0523 23.80 1.84666
9 54.0639 D9 (variable)
10 30.8461 2.0203 55.52 1.69680
11 1697.1702 D11 (variable)
12 ∞ 0.5000 (Aperture S)
13 15.5855 3.7128 63.88 1.51680
14 -13.3636 1.0121 27.57 1.75520
15 -31.5468 4.5348
16 52.8796 1.0000 29.37 1.95000
17 26.1372 4.8969
18 23.6866 2.7133 46.97 1.54072
19 -63.5925 1.9047
20 -10.9032 1.5000 46.60 1.80400
* 21 -19.7349 Bf (variable)

[Aspherical data]
4th surface κ = 1.0000
A4 = -5.26610E-06
A6 = -3.69410E-08
A8 = 1.17750E-10
A10 = -9.98120E-14

21st surface κ = 1.0000
A4 = 2.90520E-05
A6 = -1.19970E-08
A8 = -6.98280E-10
A10 = 0.00000E + 00

[Various data]
f 18.74 to 52.08
Fno 3.77 to 5.71
ω 39.16-14.81
Y 14.25-14.25
TL 79.523-109.107
Bf 18.021 〜 35.053

[Variable interval data]
(Infinity) (shooting distance 2m)
Wide-angle end Medium telephoto end Wide-angle end Medium telephoto end
f, β 18.741 34.496 52.082 -0.010 -0.018 -0.026
D0 0.000 0.000 0.000 1919.796 1906.950 1890.212
D3 1.546 11.351 25.190 1.546 11.351 25.190
D9 13.592 5.482 2.500 13.794 5.765 2.958
D11 3.099 3.099 3.099 2.897 2.816 2.641
Bf 18.021 29.172 35.053 18.021 29.172 35.053

[Lens group data]
Group number Group first surface Group focal length G1 1 100.52307
G2 4 -15.10823
G3 10 19.34026

[Conditional expression values]
Conditional expression (1): f3 / fw = 1.03
Conditional expression (2): f1 / f3 = 5.20
Conditional expression (3): f2 / (− f3) = 0.78
Conditional expression (4): f1 / (− f2) = 6.65
Conditional expression (5): ωw = 39.16
Conditional expression (6): ft / fw = 2.78

  From Table 2, it can be seen that the variable magnification optical system ZL2 according to the second example satisfies the conditional expressions (1) to (6).

  6A and 6B are aberration diagrams in the wide-angle end state (f = 18.74) of the variable magnification optical system ZL2 according to the second example. FIG. 6A is a diagram illustrating various aberrations at the time of focusing on infinity, and FIG. A coma aberration diagram when the image blur correction is performed at the time of focusing (shift amount of the anti-vibration lens group = 0.2 mm), and (c) shows various aberration diagrams at the time of focusing at a short distance (imaging magnification β = −0.010). FIG. 7 is an aberration diagram in the intermediate focal length state (f = 34.50) of the variable magnification optical system ZL2 according to the second example, (a) various aberration diagrams at the time of focusing on infinity, and (b) at infinity. Coma aberration diagram when image blur correction is performed at the time of focus (shift amount of anti-vibration lens group = 0.2 mm), (c) shows various aberration diagrams at the time of focusing at close distance (shooting magnification β = -0.018). . 8A and 8B are aberration diagrams in the telephoto end state (f = 52.08) of the variable magnification optical system ZL2 according to the second example. FIG. 8A is a diagram illustrating various aberrations at the time of focusing on infinity, and FIG. A coma aberration diagram when image blur correction is performed during focusing (shift amount of the image stabilizing lens group = 0.2 mm), and (c) shows various aberration diagrams when focusing at a short distance (imaging magnification β = −0.026).

  6 to 8 show that the variable magnification optical system ZL2 according to the second example has excellent imaging performance with various aberrations corrected well from the wide-angle end state to the telephoto end state. . It can also be seen that the image forming performance is high even when image blur correction is performed.

(Third embodiment)
A third embodiment will be described with reference to FIGS. 9 to 12 and Table 3. FIG. As shown in FIG. 9, the variable magnification optical system ZL (ZL3) according to the third example includes a first lens group G1 having positive refractive power arranged in order from the object side along the optical axis, and a negative lens group G1. It is composed of a second lens group G2 having a refractive power and a third lens group G3 having a positive refractive power.

  The first lens group G1 is composed of a cemented positive lens composed of a negative meniscus lens L11 and a biconvex lens L12 arranged in order from the object side and having a convex surface directed toward the object side.

  The second lens group G2 includes a negative meniscus lens L21 having a convex surface facing the object side, a biconcave lens L22, and a positive meniscus lens L23 having a convex surface facing the object side, which are arranged in order from the object side. The object side surface of the negative meniscus lens L21 is aspheric.

  The third lens group G3 includes a positive meniscus lens L31 having a convex surface facing the image side, a cemented positive lens composed of a biconvex lens L32 and a negative meniscus lens L33 having a convex surface facing the image side, It consists of a convex lens L34 and a biconcave lens L35. The image side surface of the negative meniscus lens L34 is aspheric.

  An aperture stop S that determines the F number is provided in the third lens group G3.

  The image plane I is formed on an image sensor (not shown), and the image sensor is composed of a CCD, a CMOS, or the like.

  The variable magnification optical system ZL3 according to the third example changes the air gap between the first lens group G1 and the second lens group G2 and the air gap between the second lens group G2 and the third lens group G3. Thus, zooming from the wide-angle end state to the telephoto end state is performed. At this time, the first lens group G1 to the third lens group G3 move toward the object side with respect to the image plane I. The aperture stop S moves to the object side together with the third lens group G3 during zooming.

  Specifically, in the zoom optical system ZL3 according to the third example, the air gap between the first lens group G1 and the second lens group G2 is increased, and the air between the second lens group G2 and the third lens group G3 is increased. Zooming from the wide-angle end state to the telephoto end state is performed by moving the lens groups G1 to G3 along the optical axis so that the interval is reduced.

  The variable magnification optical system ZL3 according to the third example is configured to perform focusing by moving the biconvex lens L34 of the third lens group G3 along the optical axis direction. As shown by the arrows in FIG. The biconvex lens L34 moves from the object side to the image side when changing from a state focused on an object at infinity to a state focused on a short distance object.

  When image blurring occurs, a positive meniscus lens L31 having a convex surface facing the image side of the third lens group G3 is moved as an anti-vibration lens group so as to have a component perpendicular to the optical axis. Perform image blur correction (anti-vibration).

  Table 3 below shows values of various specifications in the third example. Surface numbers 1 to 19 in Table 3 correspond to the optical surfaces m1 to m19 shown in FIG.

(Table 3)
[Lens data]
Surface number r D νd nd
1 53.2376 1.6000 23.80 1.84666
2 38.1514 6.3571 63.34 1.61800
3 -369.5355 D3 (variable)
* 4 37.0679 1.2789 52.34 1.75500
5 11.0000 5.1524
6 -55.1564 1.0000 46.60 1.80400
7 24.6508 0.5019
8 17.1923 3.0456 23.80 1.84666
9 55.8429 D9 (variable)
10 -147.8871 1.8235 59.42 1.58313
11 -38.8546 0.9660
12 ∞ 0.4673 (Aperture S)
13 13.2618 3.3759 65.44 1.60300
14 -18.1264 1.0943 29.37 1.95000
15 -141.8073 D15 (variable)
16 32.4435 1.9144 49.62 1.77250
* 17 -28.4962 D17 (variable)
18 -19.1230 1.1000 46.59 1.81600
19 55.1349 Bf (variable)

[Aspherical data]
4th surface κ = 1.0000
A4 = -2.53250E-05
A6 = -1.03610E-07
A8 = 7.17390E-10
A10 = -2.12490E-12

17th surface κ = 1.0000
A4 = 7.38500E-05
A6 = 4.27730E-07
A8 = 0.00000E + 00
A10 = 0.00000E + 00

[Various data]
f 18.72 to 52.00
Fno 3.60 to 5.57
ω 39.22 〜 14.29
Y 14.25-14.25
TL 74.332-95.718
Bf 18.038 to 32.068

[Variable interval data]
(Infinity) (shooting distance 2m)
Wide-angle end Medium telephoto end Wide-angle end Medium telephoto end
f, β 18.724 35.500 52.000 -0.010 -0.018 -0.027
D0 0.000 0.000 0.000 1924.987 1912.247 1903.600
D3 1.000 14.288 20.264 1.000 14.288 20.264
D9 13.907 5.856 2.000 13.907 5.856 2.000
D15 8.710 8.710 8.710 8.661 8.597 8.533
D17 3.000 3.000 3.000 3.049 3.112 3.177
Bf 18.038 25.541 32.068 18.038 25.541 32.068

[Lens group data]
Group number Group first surface Group focal length G1 1 86.38416
G2 4 -15.99559
G3 10 17.86718

[Conditional expression values]
Conditional expression (1): f3 / fw = 0.95
Conditional expression (2): f1 / f3 = 4.83
Conditional expression (3): f2 / (− f3) = 0.90
Conditional expression (4): f1 / (− f2) = 5.40
Conditional expression (5): ωw = 39.22
Conditional expression (6): ft / fw = 2.78

  From Table 3, it can be seen that the variable magnification optical system ZL3 according to the third example satisfies the conditional expressions (1) to (6).

  FIG. 10 is an aberration diagram in the wide-angle end state (f = 18.72) of the variable magnification optical system ZL3 according to Example 3, (a) Various aberration diagrams at the time of focusing on infinity, and (b) of FIG. A coma aberration diagram when the image blur correction is performed at the time of focusing (shift amount of the anti-vibration lens group = 0.2 mm), and (c) shows various aberration diagrams at the time of focusing at a short distance (imaging magnification β = −0.010). 11A and 11B are aberration diagrams in the intermediate focal length state (f = 35.50) of the variable magnification optical system ZL3 according to the third example. FIG. 11A is a diagram illustrating various aberrations at the time of focusing on infinity, and FIG. Coma aberration diagram when image blur correction is performed at the time of focus (shift amount of anti-vibration lens group = 0.2 mm), (c) shows various aberration diagrams at the time of focusing at close distance (shooting magnification β = -0.018). . 12A and 12B are aberration diagrams in the telephoto end state (f = 52.00) of the variable magnification optical system ZL3 according to the third example. FIG. 12A is a diagram illustrating various aberrations at the time of focusing on infinity, and FIG. A coma aberration diagram when image blur correction is performed at the time of focus (shift amount of the anti-vibration lens group = 0.2 mm), and (c) shows various aberration diagrams when focusing at a short distance (photographing magnification β = −0.027).

  10 to 12, it is understood that the variable magnification optical system ZL3 according to the third example has excellent imaging performance with various aberrations corrected well from the wide-angle end state to the telephoto end state. . It can also be seen that the image forming performance is high even when image blur correction is performed.

  According to each of the embodiments described above, a variable magnification optical system having good optical performance can be realized.

  Each of the above examples shows a specific example of the variable magnification optical system according to the present embodiment, and the variable magnification optical system according to the present embodiment is not limited to these. In the present embodiment, the following contents can be appropriately adopted as long as the optical performance is not impaired.

  In the numerical examples of the present embodiment, a three-group configuration is shown, but the present invention can also be applied to other group configurations such as a four-group configuration. For example, a configuration in which a lens or a lens group is added closest to the object side, or a configuration in which a lens or a lens group is added closest to the image side may be used. The lens group refers to a portion having at least one lens separated by an air interval that changes at the time of zooming or focusing.

  In the present embodiment, a single lens group, a plurality of lens groups, or a partial lens group may be moved in the optical axis direction to be a focusing lens group that performs focusing from an object at infinity to a short distance object. This focusing lens group can be applied to autofocus, and is also suitable for driving a motor for autofocus (using an ultrasonic motor or the like). In particular, it is preferable that at least a part of the third lens group G3 is a focusing lens group.

  In this embodiment, the lens group or the partial lens group is moved so as to have a component in a direction perpendicular to the optical axis, or rotated (swinged) in the in-plane direction including the optical axis, and is caused by camera shake. A vibration-proof lens group that corrects image blur may be used. In particular, it is preferable that at least a part of the third lens group G3 is an anti-vibration lens group.

  In the present embodiment, the lens surface may be formed as a spherical surface, a flat surface, or an aspheric surface. When the lens surface is a spherical surface or a flat surface, lens processing and assembly adjustment are facilitated, and optical performance deterioration due to errors in processing and assembly adjustment can be prevented. If the lens surface is aspherical, the aspherical surface is an aspherical surface by grinding, a glass mold aspherical surface that is formed of glass with an aspherical shape, or a composite type nonspherical surface that is formed of a resin on the surface of glass. Any aspherical surface may be used. The lens surface may be a diffractive surface, and the lens may be a gradient index lens (GRIN lens) or a plastic lens.

  In the present embodiment, the aperture stop S is preferably disposed in or near the third lens group G3. However, the role may be substituted by a lens frame without providing a member as an aperture stop.

  In this embodiment, each lens surface may be provided with an antireflection film having a high transmittance in a wide wavelength region in order to reduce flare and ghost and achieve high optical performance with high contrast.

  The variable magnification optical system ZL of this embodiment has a variable magnification ratio of about 2 to 7.

ZL (ZL1 to ZL3) Variable magnification optical system G1 First lens group G2 Second lens group G3 Third lens group S Aperture stop I Image plane 1 Camera (imaging device)
2 Photography lens (variable magnification optical system)

Claims (6)

Substantially three lens groups of a first lens group having a positive refractive power, a second lens group having a negative refractive power, and a third lens group having a positive refractive power, arranged in order from the object side. Consists of
At least a part of the third lens group is configured to be movable as a vibration-proof lens group for correcting image blur so as to have a component in a direction perpendicular to the optical axis,
A zoom optical system characterized by satisfying the following conditional expression:
0.60 <f3 / fw <3.50
4.76 <f1 / f3 <30.00
However,
f1: the focal length of the first lens group,
f3: focal length of the third lens group,
fw: focal length of the entire system in the wide-angle end state.   2. The zooming is performed by changing an air gap between the first lens group and the second lens group and an air gap between the second lens group and the third lens group. The zoom optical system according to 1.   When zooming from the wide-angle end state to the telephoto end state, the air gap between the first lens group and the second lens group is enlarged, and the gap between the second lens group and the third lens group is reduced. The variable magnification optical system according to claim 1 or 2, characterized in that: The zoom lens system according to any one of claims 1 to 3 , wherein the following conditional expression is satisfied.
0.60 <(− f2) / f3 <1.05
However,
f2: focal length of the second lens group. The zoom lens system according to any one of claims 1 to 4 , wherein the following conditional expression is satisfied.
5.20 <f1 / (− f2) <30.00
However,
f1: the focal length of the first lens group,
f2: focal length of the second lens group. An imaging apparatus comprising the variable magnification optical system according to any one of claims 1 to 5 .

Images