JP7841166B2 - Zoom lens and imaging device - Google Patents

Description

This invention relates to a zoom lens and an imaging device.

Patent documents 1 and 2 disclose an optical system (telephoto lens) in which a magnification conversion optical group (extender group) for extending the focal length at the telephoto end can be inserted and removed.

Patent No. 5409841 Japanese Patent Publication No. 2019-120771

In the optical systems disclosed in Patent Documents 1 and 2, an extender is provided on the image side of the aperture for the purpose of miniaturization. In this case, since it is necessary to ensure a wider spacing between lens groups on the image side of the aperture, the focusing lens group must be positioned on the object side of the aperture. When the focusing lens group is positioned on the object side of the aperture, its diameter becomes larger and heavier because it is determined by the Fno optical beam diameter at the telephoto end, making high-speed driving impossible.

Therefore, the present invention aims to provide a compact, high-performance zoom lens and imaging device that can accommodate an extender group.

One aspect of the present invention is a zoom lens comprising a first lens group with positive refractive power, a second lens group with negative refractive power, a third lens group with positive refractive power, a fourth lens group with negative refractive power, an extender group, and a fifth lens group with positive refractive power, arranged in order from the object side to the image side, wherein the spacing between adjacent lens groups changes during zooming, the focal length of the zoom lens changes when the extender group is inserted into or removed from the optical path, and the second lens group has at least four lenses, and the extender The first lens group has a cemented lens, and the lens positioned closest to the object in the first lens group has a positive refractive power. The focal length f1 of the first lens group, the focal length ft at the telephoto end of the zoom lens, the distance D on the optical axis from the fifth lens group to the fourth lens group when infinity focus is achieved at the telephoto end, the distance TL on the optical axis from the lens surface closest to the object to the image plane when infinity focus is achieved at the telephoto end, the focal length f3 of the third lens group, and the focal length f4 of the fourth lens group satisfy a predetermined conditional equation.

Other objects and features of the present invention are described in the following embodiments.

According to the present invention, it is possible to provide a compact, high-performance zoom lens and imaging device that can accommodate an extender group.

This is a cross-sectional view at the wide-angle end in Example 1. These are aberration diagrams for (a) wide-angle end, (b) intermediate zoom position, and (c) telephoto bridge in Example 1. This is a cross-sectional view at the wide-angle end in Example 2. These are aberration diagrams for (a) wide-angle end, (b) intermediate zoom position, and (c) telephoto bridge in Example 2. This is a cross-sectional view at the wide-angle end in Example 3. These are aberration diagrams for Example 3 at (a) the wide-angle end, (b) the intermediate zoom position, and (c) the telephoto bridge. This is a cross-sectional view at the wide-angle end in Example 4. These are aberration diagrams for Example 4 at (a) the wide-angle end, (b) the intermediate zoom position, and (c) the telephoto bridge. This is a cross-sectional view at the wide-angle end in Example 5. These are aberration diagrams for Example 5 at (a) the wide-angle end, (b) the intermediate zoom position, and (c) the telephoto bridge. This is a cross-sectional view at the wide-angle end in Example 6. These are aberration diagrams for Example 6 at (a) the wide-angle end, (b) the intermediate zoom position, and (c) the telephoto bridge. This is a cross-sectional view at the wide-angle end in Example 1-2. This is a cross-sectional view at the wide-angle end in Example 3-2. This is a cross-sectional view at the wide-angle end in Example 4-2. This is a cross-sectional view at the wide-angle end in Example 5-2. This is a cross-sectional view at the wide-angle end in Example 6-2. This is a schematic diagram of an imaging device equipped with an optical system in each embodiment.

The embodiments of the present invention will be described in detail below with reference to the drawings.

Figures 1, 3, 5, 7, 9, and 11 are cross-sectional views of the optical systems (zoom lenses) 1a to 1f of Examples 1 to 6 at their wide-angle ends when focused at infinity. The optical systems of each example are imaging optical systems used in imaging devices such as digital video cameras, digital still cameras, broadcast cameras, silver halide film cameras, and surveillance cameras.

In each cross-sectional view, the left side is the object side (magnifying conjugate plane side), and the right side is the image side (reducing conjugate plane side). The optical system of each embodiment is composed of, in order from the object side to the image side, the first lens group B1, the second lens group B2, the third lens group B3, the fourth lens group B4, and the fifth lens group B5. In each embodiment, a lens group is a collection of lenses that move together or remain stationary during zooming. In the optical system of each embodiment, the distance between adjacent lens groups changes during zooming from the wide-angle end to the telephoto end. The wide-angle end and telephoto end are the zoom states when the lens groups that move during zooming are positioned at both ends of the range that they can mechanically move in the direction along the optical axis OA (in the optical axis direction). Note that a lens group may consist of one lens or multiple lenses. Furthermore, a lens group may include an aperture (diaphragm) SP.

The aperture SP determines (limits) the light beam at the widest aperture F-number (Fno). The IP is the image plane (reduced conjugate plane). When the optical system of each embodiment is used as an imaging optical system for a digital video camera or digital still camera, the imaging surface of an image sensor (photoelectric conversion element) such as a CCD sensor or CMOS sensor is positioned on the image plane IP. When the optical system of each embodiment is used as an imaging optical system for a silver halide film camera, the photosensitive surface of the film is positioned on the image plane IP.

In the optical system of each embodiment, when zooming from the wide-angle end to the telephoto end, each lens group is moved as shown by the solid arrows in each cross-sectional view. Furthermore, when focusing from an object at infinity to the closest object, the fourth lens group (focusing lens group) B4 is moved as shown by the arrow "focus".

Figures 2, 4, 6, 8, 10, and 12 are longitudinal aberration diagrams of the optical systems 1a to 1f of Examples 1 to 6, respectively. In each aberration diagram, (A) shows the longitudinal aberration diagram at the wide-angle end and infinity focus, (B) shows the longitudinal aberration diagram at the intermediate zoom position and infinity focus, and (B) shows the longitudinal aberration diagram at the telephoto end and infinity focus.

In the spherical aberration diagram, Fno is the F-number, and the diagram shows the amount of spherical aberration for each of the following lines: d-line (wavelength 587.6 nm), g-line (wavelength 435.8 nm), C-line (wavelength 656.3 nm), and F-line (wavelength 486.1 nm). In the astigmatism diagram, S represents the amount of astigmatism at the sagittal image plane, and M represents the amount of astigmatism at the meridional image plane. In the distortion diagram, the amount of distortion for the d-line is shown. In the chromatic aberration diagram, the amount of chromatic aberration for each of the g-line, C-line, and F-line is shown. ω is the half-angle of view (degrees).

Next, the characteristic configurations of the optical systems (zoom lenses) in each embodiment will be described. The optical system in each embodiment has a first lens group B1 with positive refractive power, a second lens group B2 with negative refractive power, a third lens group B3 with positive refractive power, a fourth lens group B4 with negative refractive power, and a fifth lens group B5 with positive refractive power, arranged sequentially from the object side to the image side. Furthermore, the spacing between adjacent lens groups changes during zooming. The optical system in each embodiment also includes a magnification conversion optical group (extender group EXT) that changes the focal length of the zoom lens by being inserted into or removed from the optical path.

In each embodiment, the first lens group B1 satisfies the following condition (1).

0.60<f1/ft<1.50...(1)
In conditional equation (1), f1 is the focal length of the first lens group B1, and ft is the focal length at the telephoto end of the optical system. If the upper limit of conditional equation (1) is exceeded, the power (refractive force) of the first lens group B1 becomes weak. As a result, it becomes impossible to miniaturize the optical system at the telephoto end, or to lengthen the focal length at the telephoto end. On the other hand, if the lower limit of conditional equation (1) is exceeded, the power of the first lens group B1 becomes too strong. While this is effective for lengthening the focal length at the telephoto end, the excessive power leads to an increase in spherical aberration at the telephoto end, and an increase in distortion and chromatic aberration across the entire magnification range.

Furthermore, in each embodiment, the first lens group B1 and the second lens group B2 satisfy the following condition (2).

-3.90<f1/f2<-0.10...(2)
In conditional equation (2), f2 is the focal length of the second lens group B2. If the value exceeds the upper limit of conditional equation (2), the power of the second lens group B2 becomes too weak, increasing the amount of movement required to achieve the predetermined magnification and lengthening the optical system. On the other hand, if the value falls below the lower limit of conditional equation (2), the power of the second lens group B2 becomes too strong, allowing for a shorter amount of movement to achieve the predetermined magnification, but failing to suppress chromatic aberration at the wide-angle end, and failing to suppress spherical and axial chromatic aberration at the telephoto end.

Furthermore, the optical systems of each embodiment satisfy the following conditions (3) and (4).

0.10<D/TL<0.30...(3)
-5.00<f3/f4<-1.00...(4)
In condition (3), D is the distance along the optical axis from the final lens group closest to the image (the fifth lens group B5) to the lens group adjacent to the final lens group (the fourth lens group B4) when the telephoto end is in focus at infinity. TL is the distance along the optical axis from the lens surface closest to the object to the image plane IP when the telephoto end is in focus at infinity. In condition (4), f3 is the focal length of the third lens group B3, and f4 is the focal length of the fourth lens group B4.

If the upper limit of condition (3) is exceeded, the air gap containing the extender group will be made too wide. In this case, the distance from the first lens group B1 to the fourth lens group B4, which have the main imaging function, becomes too short, requiring stronger power in each lens group. This makes it difficult to suppress aberrations, or increases the number of lenses in each lens group to suppress aberrations well, thus increasing costs.

On the other hand, if the value falls below the lower limit of condition (3), the air gap surrounding the extender group becomes too narrow, resulting in an excessively small size requirement for the extender group, making it impossible to suppress aberrations within the extender group. Alternatively, it may become necessary to use aspherical lenses to effectively suppress aberrations within the extender group, leading to increased costs.

If the upper limit of condition (4) is exceeded, the power of the third lens group B3 becomes too strong relative to the fourth lens group B4. While a strong power in the third lens group B3 has the advantage of compressing the light beam incident on the subsequent fourth lens group B4, thus reducing the weight of the fourth lens group B4, exceeding the upper limit of condition (4) results in excessively large spherical and axial chromatic aberrations at the wide-angle end. Furthermore, attempting to suppress these aberrations with the third lens group B3 requires a larger number of lenses, increasing the weight and cost of the optical system.

On the other hand, if the value falls below the lower limit of condition (4), the power of the third lens group B3 becomes too weak relative to the fourth lens group B4. If the power of the third lens group B3 is too weak, it cannot compress the light beam incident on the subsequent fourth lens group B4, causing the fourth lens group B4, as the focusing lens group, to become larger in diameter. This increase in diameter of the fourth lens group B4 increases its weight, making high-speed drive impossible. Furthermore, the optical system becomes longer due to the difficulty in focusing the light beam. If an attempt is made to increase the power of the fifth lens group B5, the final lens group, to prevent this, the ray angle of the off-axis rays also changes sharply, leading to an increase in chromatic aberration.

In the optical systems of each embodiment, the final lens group (fifth lens group B5) is fixed (it remains immobile during zooming). This is because, when a built-in extender insertion/removal mechanism is provided in the space directly in front of the final lens group, it is difficult to construct the group with the same cam across the built-in extender.

Preferably, the optical system of each embodiment satisfies the following condition (5).

-0.50<f4/ft<-0.05...(5)
If the value falls below the lower limit of condition (5), the power of the fourth lens group B4 becomes too weak. When the power of the fourth lens group B4, which is the focusing lens group, becomes weak, it becomes necessary to ensure a larger travel distance when focusing, which either makes the optical system larger or narrows the focusing range. On the other hand, if the value exceeds the upper limit of condition (5), the power of the fourth lens group B4 becomes too strong. When the power of the fourth lens group B4 becomes strong, there is the advantage that the group travel distance when focusing can be shortened, but it becomes necessary to increase the number of elements in the fourth lens group B4 in order to suppress aberration fluctuations when focusing, which increases the weight of the fourth lens group B4.

Furthermore, preferably, the optical system of each embodiment satisfies the following condition (6).

0.10<f5/ft<2.00...(6)
In conditional equation (6), f5 is the focal length of the fifth lens group B5. If the value exceeds the upper limit of conditional equation (6), the power of the fifth lens group B5 becomes too weak. The fifth lens group B5 has the role of forming an image on the sensor surface (image plane IP) while matching the image plane size, based on the light beam emitted from the fourth lens group B4, and also has the function of canceling out distortion aberration that could not be suppressed by the first lens group B1. If the power of the fifth lens group B5 becomes too weak, it will no longer be able to cancel out distortion aberration. On the other hand, if the value falls below the lower limit of conditional equation (6), the power of the fifth lens group B5 becomes too strong. If the power of the fifth lens group B5 becomes too strong, the amount of distortion generated will increase, and even if the distortion aberration generated in the first lens group B1 is canceled out, distortion aberration will still occur within the fifth lens group B5.

More preferably, the numerical ranges of conditional expressions (1) to (6) are set to satisfy the following conditional expressions (1a) to (6b).

0.61<f1/ft<1.20...(1a)
-3.80<f1/f2<-1.00...(2a)
0.12<D/TL<0.25...(3a)
-3.50<f3/f4<-1.03...(4a)
-0.30<f4/ft<-0.06...(5a)
0.15<f5/ft<1.00...(6a)
More preferably, the numerical ranges of conditional expressions (1) to (6) are set to satisfy the following conditional expressions (1b) to (6b).

0.62<f1/ft<1.00...(1b)
-3.70<f1/f2<-2.00...(2b)
0.15<D/TL<0.20...(3b)
-2.00<f3/f4<-1.06...(4b)
-0.20<f4/ft<-0.07...(5b)
0.20<f5/ft<0.80...(6b)
Next, the optical systems of each embodiment will be described.

First, with reference to Figure 1, the optical system 1a in Embodiment 1 will be described. The optical system 1a in this embodiment is a telephoto zoom lens. As shown in Figure 1, the optical system 1a consists of, in order from the object side to the image side, a first lens group B1 with positive refractive power, a second lens group B2 with negative refractive power, a third lens group B3 with positive refractive power, a fourth lens group B4 with negative refractive power, and a fifth lens group B5 with positive refractive power. A space is provided between the fourth lens group B4 and the fifth lens group B5 through which a magnification conversion optical group (extender group) can be inserted or removed. During zooming, the second lens group B2 and the fourth lens group B4 move. The second lens group B2 primarily has a magnification function, while the fourth lens group B4 has a function to correct the focus position that moves during magnification.

The first lens group B1 contributes to the compression of the entire optical system at the telephoto end. The first lens group B1 is fixed (immovable) during zooming and is configured to enhance dust and splash resistance, increasing robustness in adverse weather conditions. The first lens group B1 consists of a first lens with positive refractive power, a second lens with positive refractive power, a third lens with positive refractive power, and a fourth lens with negative refractive power. The third and fourth lenses are cemented lenses. The first and second lenses have a strong light-gathering effect, and the third lens is made smaller in diameter by increasing the air gap between the second and third lenses. If the number of light-gathering lenses for the first and second lenses were reduced to one, spherical aberration at the telephoto end would increase. Furthermore, the cemented lens formed by the third and fourth lenses has a negative power combined focal length, and possesses the function of canceling out spherical aberration generated by the first and second lenses at the telephoto end, as well as the function of canceling out distortion generated by the first and second lenses throughout the entire zoom range.

The second lens group B2 moves from the object side (in the direction of magnification conjugate) to the image side (in the direction of reduction conjugate) from the wide-angle end to the telephoto end, thereby shifting the primary imaging performance to the third lens group B3 at the wide-angle end and to the first lens group B1 at the telephoto end. The lens diameter of the second lens group B2 is determined by the off-axis marginal rays at the wide-angle end or the on-axis marginal rays at the telephoto end. At the wide-angle end, the off-axis marginal rays are sufficiently focused by the first lens group B1, thus preventing an increase in the diameter of the second lens group B2. At the telephoto end, the on-axis marginal rays are sufficiently focused as the second lens group B2 moves in the direction of the reduction conjugate plane, preventing an increase in the diameter of the second lens group B2.

However, if the second lens group B2 has positive refractive power, it moves from the reducing conjugate plane side to the expanding conjugate plane side when zooming from the wide-angle end to the telephoto end. In this case, the lens diameter of the second lens group B2 becomes larger and heavier because it is determined by the axial marginal ray height at the telephoto end. Furthermore, a convex lens with positive refractive power is included as a fourth lens within the second lens group B2. This makes it easier to align the image plane with the second lens group B2, which has negative refractive power. Also, three lenses with negative refractive power are included within the second lens group B2. This allows for the suppression of various aberrations by gently bending off-axis rays at the wide-angle end. It is preferable that the second lens group B2 has at least four lenses.

The third lens group B3 contributes to the compression of the entire optical system at the wide-angle end. Low-dispersion convex lenses are used to suppress axial chromatic aberration. In this embodiment, the third lens group B3 does not move during zooming, but it may be made to move during zooming to suppress aberration fluctuations.

The fourth lens group is a variable magnification lens group that moves during zooming. During focusing, it moves from the magnification conjugate direction to the reduction conjugate direction from infinity to the near end, forming an image of the light beam on the sensor surface. In this embodiment, a cemented lens is used in the focusing lens group, resulting in a configuration that easily suppresses chromatic aberration even when the power of the lens group is increased.

The fifth lens group B5 is a field lens that forms an image on the image sensor surface of the light emitted from the fourth lens group B4. In this embodiment, by positioning the negative lens on the side of the conjugate plane closest to the reduction, it is possible to satisfy the incident angle condition to the image sensor. Furthermore, by creating an air gap between the negative lens and the positive lens positioned directly in front of it within the fifth lens group B5, the height of the off-axis light rays incident on the positive lens is increased, canceling the distortion aberration generated by the negative lens. In this case, the positive lens is a cemented lens to prevent the separation of light rays by color across the air gap. That is, the final lens group (fifth lens group B5) consists of a cemented lens formed by joining a positive lens and a negative lens, and a negative lens positioned on the image side of the cemented lens. The fifth lens group B5 also plays a role in canceling out distortion aberrations that cannot be suppressed by the first lens group B1.

Figure 13 is a cross-sectional view of the optical system 1a in Figure 1 with the extender group EXT inserted, at the wide-angle end when focusing at infinity. By inserting the extender group EXT between the fourth lens group B4 and the fifth lens group B5 of the optical system 1a in Figure 1, the focal length is increased by approximately 1.4 times, enabling the realization of a more telephoto optical system.

Next, with reference to Figure 2, the optical system 1b in Embodiment 2 will be described. The optical system 1b in this embodiment differs from the optical system 1a in Embodiment 1 in that the fifth lens group B5 has an aspherical lens. That is, optical system 1b achieves good image plane correction by placing an aspherical lens in the fifth lens group B5, where off-axis rays are separated. In this embodiment, the aspherical lens is formed by bonding a resin material to glass, but the glass itself may have an aspherical shape. Also, while the bonding target is a cemented lens, it may be bonded to a single lens.

Next, with reference to Figure 5, the optical system 1c in Example 3 will be described. Compared to the optical system 1b in Example 2, the optical system 1c in this example has one less lens constituting the fourth lens group B4, enabling higher-speed driving.

Figure 14 is a cross-sectional view of the optical system 1c in Figure 5 with the extender group EXT inserted, at the wide-angle end when focusing at infinity. By inserting the extender group EXT between the fourth lens group B4 and the fifth lens group B5 of the optical system 1c, the focal length is increased by approximately 1.4 times, enabling the realization of a more telephoto optical system.

Next, with reference to Figure 7, the optical system 1d in Example 4 will be described. Compared to the optical system 1a in Example 1, the optical system 1d in this example extends the telephoto end toward the longer focal length. This further expands the expressive range.

Figure 15 is a cross-sectional view of the optical system 1d in Figure 7 with the extender group EXT inserted, at the wide-angle end when focusing at infinity. By inserting the extender group EXT between the fourth lens group B4 and the fifth lens group B5 of the optical system 1d, the focal length is increased by approximately 1.4 times, enabling the realization of a more telephoto optical system.

Next, with reference to Figure 9, the optical system 1e in Example 5 will be described. The optical system 1e in this example differs from the optical system 1a in Example 1 in that the third lens group B3 moves during zooming. The movement of the third lens group B3 during zooming enables better aberration correction.

Figure 16 is a cross-sectional view of the optical system 1e in Figure 9 with the extender group EXT inserted, at the wide-angle end when focusing at infinity. By inserting the extender group EXT between the fourth lens group B4 and the fifth lens group B5 of the optical system 1e, the focal length is increased by approximately 1.4 times, enabling the realization of a more telephoto optical system.

Next, with reference to Figure 11, the optical system 1f in Embodiment 6 will be described. The optical system 1f in this embodiment differs from the optical system 1a in Embodiment 1 in that the first lens group B1 moves during zooming. The movement of the first lens group B1 during zooming enables better aberration correction at the telephoto end.

Figure 17 is a cross-sectional view of the optical system 1f in Figure 11 with the extender group EXT inserted, at the wide-angle end when focusing at infinity. By inserting the extender group EXT between the fourth lens group B4 and the fifth lens group B5 of the optical system 1e, the focal length is increased by approximately 1.4 times, enabling the realization of a more telephoto optical system.

Below are numerical examples 1-6 corresponding to Examples 1-6, and numerical examples 1-2, 3-2 to 6-2 corresponding to Examples 1, 3-6 with a built-in (inserted) magnification conversion optical group (extender group).

In the surface data for each numerical example, r represents the radius of curvature of each optical surface, and d (mm) represents the on-axial spacing (distance along the optical axis) between the m-th surface and the (m+1)-th surface. Here, m is the surface number counted from the light incident side. Also, nd represents the refractive index of each optical element with respect to the d-line, and νd represents the Abbe number of the optical element with respect to the d-line. The Abbe number νd is given by Nd, NF, and NC, respectively, when the refractive indices at the Fraunhofer lines d-line (587.6 nm), F-line (486.1 nm), and C-line (656.3 nm) are Nd, NF, and NC.
νd=(Nd-1)/(NF-NC)
It is represented as follows.

In each numerical example, d, focal length (mm), F-number, and half-angle of view (degrees) are all values when the optical system of each example is focused on an object at infinity (infinity focus). "Back focus" is the distance along the optical axis from the final lens surface (the lens surface closest to the image) to the paraxial image plane, expressed in air equivalent length. "Total lens length" is the distance along the optical axis from the frontmost lens surface (the lens surface closest to the object) to the final surface of the optical system, plus the back focus. "Lens group" includes not only cases composed of multiple lenses, but also cases composed of a single lens.

Furthermore, if the optical surface is aspherical, the symbol "*" is added to the right of the surface number. The aspherical shape is expressed by the following formula, where x is the displacement from the surface vertex in the optical axis direction, h is the height from the optical axis perpendicular to the optical axis, R is the paraaxial radius of curvature, k is the cone constant, and A4, A6, A8, A10, A12, and A14 are the aspherical coefficients of their respective orders.

x=(h ² /R)/[1+{1-(1+k)(h/R) ² } ^1/2 +A4×h ⁴ +A6×h ⁶ +A8×h ⁸ +A10×h ¹⁰ +A12×h ¹² +A14×h ¹⁴
Note that "e±XX" in each aspherical coefficient means "×10± ^XX ".

(Numerical Example 1)

Face number rd nd νd
1 273.176 7.081 1.487 70.2
2 -1361.262 0.300
3 113.868 11.427 1.434 95.1
4 1751.273 28.392
5 104.514 9.931 1.497 81.5
6 -530.570 2.400 1.735 49.8
7 87.663 (variable)
8 85.600 1.800 1.750 35.3
9 34.633 4.083 1.816 46.6
10 43.494 7.461
11 -198.501 1.700 1.528 76.5
12 110.708 0.473
13 63.583 5.393 1.789 28.4
14 602.245 2.877
15 -107.425 1.500 1.497 81.5
16 331.917 (variable)
17 153.599 3.301 1.497 81.5
18 21625.358 0.136
19 57.826 5.529 1.497 81.5
20 398.525 19.982
21 (aperture) ∞ 0.500
22 76.071 2.773 1.497 81.5
23 149.129 7.313
24 -306.956 2.000 1.695 42.2
25 48.393 2.415
26 92.105 1.800 1.800 29.8
27 64.222 6.992 1.497 81.5
28 -136.344 0.150
29 96.638 2.687 1.816 46.6
30 330.341 1.000
31 40.630 4.639 1.497 81.5
32 419.832 (variable)
33 373.891 3.439 1.893 20.4
34 -145.171 1.300 1.852 40.8
35 55.255 2.000
36 993.429 2.000 1.852 40.8
37 63.079 (Variable)
38 76.040 13.902 1.603 38
39 -46.009 1.980 1.808 22.8
40 -72.949 25.690
41 -54.037 1.981 1.729 54.7
42 -229.615 (variable)
Image plane ∞

Wide-angle end, intermediate, telephoto end
d7 5.082 36.908 66.439
d16 62.324 30.499 0.967
d32 3.399 3.021 0.413
d37 58.493 58.870 61.479
d42 39.994 39.994 39.994

Wide-angle end, intermediate, telephoto end: Focal length 206.1, 285.0, 385.5
F-number 4.1 4.1 4.1
Half-angle 5.99 4.34 3.21
Image height 21.635 21.635 21.635
Lens length 367.62 367.62 367.62
BF 39.994 39.994 39.994

(Numerical Example 2)

Face number rd nd νd
1 172.811 9.690 1.487 70.2
2 -4247.264 0.300
3 103.511 11.950 1.434 95.1
4 731.898 18.548
5 90.460 10.390 1.497 81.5
6 -1781.164 2.400 1.773 49.6
7 74.154 (variable)
8 94.630 1.800 1.852 40.8
9 57.576 15.361
10 -328.669 1.700 1.528 76.5
11 95.106 0.991
12 76.714 4.156 1.789 28.4
13 268.446 3.769
14 -110.310 1.500 1.497 81.5
15 -2527.313 (variable)
16 141.332 3.918 1.497 81.5
17 -887.059 0.500
18 61.469 5.534 1.497 81.5
19 491.553 29.245
20 (aperture) ∞ 1.513
21 -301.746 2.000 1.654 39.7
22 53.300 2.202
23 92.105 1.800 1.800 29.8
24 64.222 6.992 1.497 81.5
25 -136.344 0.150
26 96.638 2.687 1.816 46.6
27 330.341 1.000
28 42.050 4.363 1.497 81.5
29 213.941 (variable)
30 733.553 1.727 1.893 20.4
31 -190.560 1.300 1.852 40.8
32 47.179 2.000
33 288.374 1.500 1.816 46.6
34 116.899 (variable)
35* 124.390 0.100 1.516 52.2
36 106.287 10.627 1.800 29.8
37 -45.171 1.500 1.808 22.8
38 -158.049 26.842
39 -36.745 1.500 1.729 54.7
40 -61.263 (variable)
Image plane ∞

K c4 c6
d35 0 1.220E-06 3.722E-10
(c8 and later 0)

Wide-angle end, intermediate, telephoto end
d7 2.608 40.865 61.367
d15 59.708 21.451 0.949
d29 5.525 3.956 0.900
d34 58.670 60.239 63.295
d40 39.983 39.983 39.983

Wide-angle end, intermediate, telephoto end: Focal length 206.4, 309.0, 383.7
F-number 4.1 4.1 4.1
Half-angle 5.98 4.01 3.23
Image height 21.635 21.635 21.635
Lens length 358.05 358.05 358.05
BF 39.983 39.983 39.983

(Numerical Example 3)

Face number rd nd νd
1 217.020 7.911 1.487 70.2
2 -2114.635 0.300
3 108.060 10.941 1.434 95.1
4 799.040 24.642
5 90.882 10.000 1.497 81.5
6 -6626.810 2.400 1.773 49.6
7 77.778 (variable)
8 119.161 1.800 2.001 29.1
9 60.733 6.079
10 -255.201 1.700 1.497 81.5
11 111.954 2.949
12 83.304 4.599 1.855 24.8
13 562.828 3.746
14 -99.723 1.500 1.497 81.5
15 -508.786 (variable)
16 84.172 5.253 1.497 81.5
17 3474.868 0.500
18 80.008 3.901 1.497 81.5
19 250.578 29.600
20 (aperture) ∞ 4.369
21 -271.566 2.000 1.673 38.1
22 59.960 4.617
23 92.105 1.800 1.917 31.6
24 64.222 6.992 1.497 81.5
25 -136.344 0.150
26 96.638 2.687 1.773 49.6
27 330.341 0.999
28 52.525 3.596 1.595 67.7
29 149.095 (variable)
30 481.601 2.203 1.847 23.8
31 -148.197 1.300 1.852 40.8
32 52.346 (Variable)
33* 164.208 0.100 1.516 52.2
34 132.826 9.566 1.728 28.5
35 -45.927 1.500 1.893 20.4
36 -96.765 29.578
37 -37.293 1.500 1.603 65.4
38 -90.046 (variable)
Image plane ∞

K c4 c6
d33 0 1.359E-06 3.603E-10
(c8 and later 0)

Wide-angle end, intermediate, telephoto end
d7 4.488 45.159 66.335
d15 62.784 22.113 0.937
d29 6.291 4.688 1.171
d32 64.037 65.641 69.158
d38 39.996 39.996 39.996

Wide-angle end, intermediate, telephoto end: Focal length 207.5, 309.0, 380.8
F-number 4.1 4.1 4.1
Half-angle 5.95 4.01 3.25
Image height 21.635 21.635 21.635
Lens length 368.37 368.37 368.37
BF 39.996 39.996 39.996

(Numerical Example 4)

Face number rd nd νd
1 378.419 7.846 1.487 70.2
2 -1795.818 0.300
3 124.251 13.930 1.434 95.1
4 354.219 13.144
5 180.269 2.400 1.816 46.6
6 84.396 16.515 1.497 81.5
7 281.924 (variable)
8 75.201 9.000 1.487 70.2
9 461.766 20.035
10 157.306 1.800 1.640 60.1
11 42.872 7.973
12 -276.069 1.70 1.497 81.5
13 78.946 4.400
14 63.389 4.46 1.689 31.1
15 230.448 4.234
16 -99.501 1.50 1.729 54.7
17 608.107 (variable)
18 151.875 3.195 1.497 81.5
19 -6463.820 0.136
20 53.310 6.003 1.497 81.5
21 325.154 19.982
22 (aperture) ∞ -0.011
23 65.814 3.572 1.497 81.5
24 179.245 6.029
25 -387.556 2.000 1.816 46.6
26 46.392 3.924
27 92.105 1.80 1.800 29.8
28 64.222 6.992 1.497 81.5
29 -136.344 0.150
30 96.638 2.687 1.816 46.6
31 330.341 0.850
32 40.899 4.482 1.497 81.5
33 192.210 (Variable)
34 174.243 4.01 1.808 22.8
35 -124.275 1.300 1.905 35
36 52.408 2.000
37 891.396 1.500 1.816 46.6
38 79.504 (Variable)
39 79.836 12.286 1.648 33.8
40 -52.481 1.980 1.923 18.9
41 -80.657 26.083
42 -58.066 1.981 1.729 54.7
43 -410.070 (variable)
Image plane ∞

Wide-angle end, intermediate, telephoto end
d7 3.056 37.811 79.339
d17 77.263 42.508 0.980
d33 5.122 5.699 0.279
d38 62.439 61.862 67.282
d43 39.998 39.998 39.998

Wide-angle end, intermediate, telephoto end: Focal length 207.0, 306.0, 487.9
F-number 4.1 4.1 4.1
Half-angle 5.97 4.04 2.54
Image height 21.635 21.635 21.635
Lens length 410.05 410.05 410.05
BF 39.998 39.998 39.998

(Numerical Example 5)

Face number rd nd νd
1 286.607 6.840 1.487 70.2
2 -1463.003 0.300
3 111.246 11.738 1.434 95.1
4 1749.209 27.948
5 98.098 13.041 1.497 81.5
6 -545.177 2.400 1.735 49.8
7 81.765 (variable)
8 83.258 1.800 1.750 35.3
9 33.749 4.066 1.816 46.6
10 42.417 7.154
11 -180.665 1.700 1.528 76.5
12 113.470 0.466
13 61.787 5.339 1.789 28.4
14 581.763 2.802
15 -105.706 1.500 1.497 81.5
16 204.478 (variable)
17 138.794 3.690 1.497 81.5
18 -876.951 0.136
19 58.535 5.262 1.497 81.5
20 452.891 19.982
21 (aperture) ∞ 0.500
22 71.448 2.623 1.497 81.5
23 127.256 5.249
24 -349.339 2.000 1.695 42.2
25 49.166 2.305
26 92.105 1.800 1.800 29.8
27 64.222 6.992 1.497 81.5
28 -136.344 0.150
29 96.638 2.687 1.816 46.6
30 330.341 1.000
31 41.541 4.323 1.497 81.5
32 340.942 (variable)
33 385.851 3.853 1.893 20.4
34 -148.541 1.300 1.852 40.8
35 56.735 2.000
36 1096.989 2.000 1.852 40.8
37 62.616 (Variable)
38 79.788 13.608 1.603 38.0
39 -46.706 1.980 1.808 22.8
40 -73.893 27.238
41 -55.378 1.981 1.729 54.7
42 -189.233 (variable)
Image plane ∞

Wide-angle end, Mid-range, Telephoto end
d 7 7.219 44.774 63.898
d16 61.961 21.661 0.969
d32 1.990 2.039 0.524
d37 56.507 59.203 62.285
d42 39.997 39.997 39.997

Wide-angle end, intermediate, telephoto end: Focal length 200.1, 309.0, 386.1
F-number 4.1 4.1 4.1
Half-angle 6.17 4.01 3.21
Image height 21.635 21.635 21.635
Lens length 367.43 367.43 367.43
BF 39.997 39.997 39.997

(Numerical Example 6)

Face number rd nd νd
1 283.661 6.931 1.487 70.2
2 -1412.95 0.300
3 119.771 10.893 1.434 95.1
4 1560.631 31.701
5 110.911 9.439 1.497 81.5
6 -568.7 2.400 1.735 49.8
7 93.198 (variable)
8 92.995 1.800 1.750 35.3
9 34.391 4.274 1.816 46.6
10 44.216 7.528
11 -180.117 1.700 1.528 76.5
12 121.148 0.484
13 65.973 5.511 1.789 28.4
14 1359.812 2.721
15 -105.632 1.500 1.497 81.5
16 399.221 (variable)
17 178.567 3.256 1.497 81.5
18 -1602.05 0.136
19 58.361 5.561 1.497 81.5
20 400.782 19.982
21 (aperture) ∞ 0.500
22 75.552 3.042 1.497 81.5
23 174.59 8.414
24 -270.101 2.000 1.695 42.2
25 48.432 2.417
26 92.105 1.800 1.800 29.8
27 64.222 6.992 1.497 81.5
28 -136.344 0.150
29 96.638 2.687 1.816 46.6
30 330.341 1.000
31 40.329 4.723 1.497 81.5
32 484.054 (variable)
33 415.075 2.862 1.893 20.4
34 -144.135 1.300 1.852 40.8
35 53.349 2.000
36 1181.562 2.000 1.852 40.8
37 65.624 (Variable)
38 75.851 14.180 1.603 38.0
39 -46.623 1.980 1.808 22.8
40 -74.984 28.545
41 -52.714 1.981 1.729 54.7
42 -198.68 (variable)
Image plane ∞

Wide-angle end, Mid-range, Telephoto end
d 7 3.802 39.570 72.602
d16 56.962 27.574 0.979
d32 3.329 2.974 0.419
d37 8.410 8.764 11.319
d42 39.993 39.993 39.993

Wide-angle end, intermediate, telephoto end: Focal length 206.1, 285.0, 386.5
F-number 4.1 4.1 4.1
Half-angle 5.99 4.34 3.2
Image height 21.635 21.635 21.635
Lens length: 367.18 373.56 380.00
BF 39.993 39.993 39.993

(Numerical Examples 1-2)

Face number rd nd νd
1 273.176 7.081 1.487 70.2
2 -1361.262 0.300
3 113.868 11.427 1.434 95.1
4 1751.273 28.392
5 104.514 9.931 1.497 81.5
6 -530.570 2.400 1.735 49.8
7 87.663 5.082
8 85.600 1.800 1.750 35.3
9 34.633 4.083 1.816 46.6
10 43.494 7.461
11 -198.501 1.700 1.528 76.5
12 110.708 0.473
13 63.583 5.393 1.789 28.4
14 602.245 2.877
15 -107.425 1.500 1.497 81.5
16 331.917 (variable)
17 153.599 3.301 1.497 81.5
18 21625.358 0.136
19 57.826 5.529 1.497 81.5
20 398.525 19.982
21 (aperture) ∞ 0.500
22 76.071 2.773 1.497 81.5
23 149.129 7.313
24 -306.956 2.000 1.695 42.2
25 48.393 2.415
26 92.105 1.800 1.800 29.8
27 64.222 6.992 1.497 81.5
28 -136.344 0.150
29 96.638 2.687 1.816 46.6
30 330.341 1.000
31 40.630 4.639 1.497 81.5
32 419.832 (variable)
33 373.891 3.439 1.893 20.4
34 -145.171 1.300 1.852 40.8
35 55.255 2.000
36 993.429 2.000 1.852 40.8
37 63.079 (Variable)
38(Ext) 44.327 3.841 1.497 81.5
39(Ext) -344.994 2.227
40(Ext) 19.184 4.493 1.517 52.4
41(Ext) 46.384 1.150 1.883 40.8
42(Ext) 19.213 10.053
43(Ext) -281.796 0.950 1.905 35
44(Ext) 21.867 6.568 1.738 32.3
45(Ext) -46.055 0.950 1.804 46.6
46(Ext) 81.160 0.497
47(Ext) 48.448 7.081 1.613 44.3
48(Ext) -23.570 1.050 1.595 67.7
49(Ext) 136.359 (Variable)
50 76.040 13.902 1.603 38
51 -46.009 1.980 1.808 22.8
52 -72.949 25.690
53 -54.037 1.981 1.729 54.7
54 -229.615 (variable)
Image plane ∞

Wide-angle end, Mid-range, Telephoto end
d7 5.082 36.908 66.439
d16 62.324 30.499 0.967
d32 3.399 3.021 0.413
d37 8.498 8.876 11.484
d49 11.135 11.135 11.135
d54 39.994 39.994 39.994

Wide-angle end, intermediate, telephoto end: Focal length 290.4, 401.6, 543.2
F-number 5.8 5.8 5.8
Half-angle 4.26 3.08 2.28
Image height 21.635 21.635 21.635
Lens length 367.62 367.62 367.62
BF 39.994 39.994 39.994

(Numerical Example 3-2)

Face number rd nd νd
1 217.020 7.911 1.487 70.2
2 -2114.635 0.300
3 108.060 10.941 1.434 95.1
4 799.040 24.642
5 90.882 10.000 1.497 81.5
6 -6626.810 2.400 1.773 49.6
7 77.778 (variable)
8 119.161 1.800 2.001 29.1
9 60.733 6.079
10 -255.201 1.700 1.497 81.5
11 111.954 2.949
12 83.304 4.599 1.855 24.8
13 562.828 3.746
14 -99.723 1.500 1.497 81.5
15 -508.786 62.784
16 84.172 (variable) 1.497 81.5
17 3474.868 0.500
18 80.008 3.901 1.497 81.5
19 250.578 29.600
20 (aperture) ∞ 4.369
21 -271.566 2.000 1.673 38.1
22 59.960 4.617
23 92.105 1.800 1.917 31.6
24 64.222 6.992 1.497 81.5
25 -136.344 0.150
26 96.638 2.687 1.773 49.6
27 330.341 0.999
28 52.525 3.596 1.595 67.7
29 149.095 (variable)
30 481.601 2.203 1.847 23.8
31 -148.197 1.300 1.852 40.8
32 52.346 (Variable)
33(Ext) 832.656 2.664 1.673 32.1
34(Ext) -192.540 0.962
35(Ext) 22.864 3.891 1.595 67.7
36(Ext) 34.795 1.150 1.706 30.2
37(Ext) 26.166 15.829
38(Ext) 183.567 0.950 2.001 25.5
39(Ext) 16.536 9.776 1.789 28.4
40(Ext) -29.622 0.950 1.883 40.8
41(Ext) 53.989 0.904
42(Ext) 34.486 9.907 1.581 40.8
43(Ext) -18.478 1.050 1.595 67.7
44(Ext) 85.879 (Variable)
45* 164.208 0.100 1.516 52.2
46 132.826 9.566 1.728 28.5
47 -45.927 1.500 1.893 20.4
48 -96.765 29.578
49 -37.293 1.500 1.603 65.4
50 -90.046 (variable)
Image plane ∞

K c4 c6
d45 0 1.359E-06 3.603E-10
(c8 and later 0)

Wide-angle end, Mid-range, Telephoto end
d7 4.488 45.159 66.335
d15 62.784 22.113 0.937
d29 6.291 4.688 1.171
d32 14.043 15.647 19.163
d44 1.961 1.961 1.961
d50 39.995 39.995 39.995

Wide-angle end, intermediate, telephoto end: Focal length 295.9, 440.8, 543.2
F-number 5.9 5.8 5.9
Half-angle 4.18 2.81 2.28
Image height 21.635 21.635 21.635
Lens length 368.37 368.37 368.37
BF 39.995 39.995 39.995

(Numerical Example 4-2)

Face number rd nd νd
1 378.419 7.846 1.487 70.2
2 -1795.818 0.300
3 124.251 13.930 1.434 95.1
4 354.219 13.144
5 180.269 2.400 1.816 46.6
6 84.396 16.515 1.497 81.5
7 281.924 (variable)
8 75.201 9.000 1.487 70.2
9 461.766 20.035
10 157.306 1.800 1.640 60.1
11 42.872 7.973
12 -276.069 1.700 1.497 81.5
13 78.946 4.400
14 63.389 4.462 1.689 31.1
15 230.448 4.234
16 -99.501 1.500 1.729 54.7
17 608.107 (variable)
18 151.875 3.195 1.497 81.5
19 -6463.820 0.136
20 53.310 6.003 1.497 81.5
21 325.154 19.982
22 (aperture) ∞ -0.011
23 65.814 3.572 1.497 81.5
24 179.245 6.029
25 -387.556 2.000 1.816 46.6
26 46.392 3.924
27 92.105 1.800 1.800 29.8
28 64.222 6.992 1.497 81.5
29 -136.344 0.150
30 96.638 2.687 1.816 46.6
31 330.341 0.850
32 40.899 4.482 1.497 81.5
33 192.210 (Variable)
34 174.243 4.011 1.808 22.8
35 -124.275 1.300 1.905 35
36 52.408 2.000
37 891.396 1.500 1.816 46.6
38 79.504 (Variable)
39(Ext) 24.675 6.188 1.622 53.2
40(Ext) -184.787 0.300
41(Ext) 429.639 4.984 1.595 67.7
42(Ext) -28.938 1.150 1.622 53.2
43(Ext) 31.228 8.578
44(Ext) -56.537 0.950 2.001 29.1
45(Ext) 18.702 10.795 1.648 33.8
46(Ext) -15.250 0.950 1.729 54.7
47(Ext) -63.757 0.499
48(Ext) 45.665 10.512 1.517 52.4
49(Ext) -18.772 1.050 1.497 81.5
50 80.729 (Variable)
51 79.836 12.286 1.648 33.8
52 -52.481 1.980 1.923 18.9
53 -80.657 26.083
54 -58.066 1.981 1.729 54.7
55 -410.070 (variable)
Image plane ∞

Wide-angle end, intermediate, telephoto end
d7 3.056 37.811 79.339
d17 77.263 42.508 0.980
d33 5.122 5.699 0.279
d38 12.444 11.868 17.287
d50 4.039 4.039 4.039
d55 39.998 39.998 39.998

Wide-angle end, intermediate, telephoto end: Focal length 288.1, 425.7, 678.9
F-number 5.7 5.7 5.7
Half-angle 4.30 2.91 1.83
Image height 21.635 21.635 21.635
Lens length 410.05 410.05 410.05
BF 39.998 39.998 39.998

(Numerical Example 5-2)

Face number rd nd νd
1 286.607 6.840 1.487 70.2
2 -1463 0.300
3 111.246 11.738 1.434 95.1
4 1749.209 27.948
5 98.098 13.041 1.497 81.5
6 -545.177 2.400 1.735 49.8
7 81.765 (variable)
8 83.258 1.800 1.750 35.3
9 33.749 4.066 1.816 46.6
10 42.417 7.154
11 -180.665 1.700 1.528 76.5
12 113.47 0.466
13 61.787 5.339 1.789 28.4
14 581.763 2.802
15 -105.706 1.500 1.497 81.5
16 204.478 (variable)
17 138.794 3.690 1.497 81.5
18 -876.951 0.136
19 58.535 5.262 1.497 81.5
20 452.891 19.982
21 (aperture) ∞ 0.500
22 71.448 2.623 1.497 81.5
23 127.256 5.249
24 -349.339 2.000 1.695 42.2
25 49.166 2.305
26 92.105 1.800 1.800 29.8
27 64.222 6.992 1.497 81.5
28 -136.344 0.150
29 96.638 2.687 1.816 46.6
30 330.341 1.000
31 41.541 4.323 1.497 81.5
32 340.942 (variable)
33 385.851 3.853 1.893 20.4
34 -148.541 1.300 1.852 40.8
35 56.735 2.000
36 1096.989 2.000 1.852 40.8
37 62.616 (Variable)
38(Ext) 44.379 3.741 1.497 81.5
39(Ext) -292.043 2.160
40(Ext) 19.215 4.687 1.517 52.4
41(Ext) 51.561 1.150 1.883 40.8
42(Ext) 19.175 8.692
43(Ext) -293.666 0.950 1.905 35.0
44(Ext) 23.442 6.638 1.738 32.3
45(Ext) -48.256 0.950 1.804 46.6
46(Ext) 90.003 0.400
47(Ext) 50.373 7.573 1.613 44.3
48(Ext) -23.216 1.050 1.595 67.7
49(Ext) 126.385 (Variable)
50 79.788 13.608 1.603 38.0
51 -46.706 1.980 1.808 22.8
52 -73.893 27.238
53 -55.378 1.981 1.729 54.7
54 -189.233 (variable)
Image plane ∞

Wide-angle end, Mid-range, Telephoto end
d 7 7.219 44.774 63.898
d16 61.961 21.661 0.969
d32 1.990 2.039 0.524
d37 6.512 9.209 12.291
d49 12.003 12.003 12.003
d54 39.997 39.997 39.997

Wide-angle end, intermediate, telephoto end: Focal length 278.4, 429.9, 537.2
F-number 5.7 5.7 5.7
Half-angle 4.44 2.88 2.31
Image height 21.635 21.635 21.635
Lens length 367.43 367.43 367.43
BF 39.997 39.997 39.997

(Numerical Example 6-2)

Face number rd nd νd
1 283.661 6.931 1.487 70.2
2 -1412.95 0.300
3 119.771 10.893 1.434 95.1
4 1560.631 31.701
5 110.911 9.439 1.497 81.5
6 -568.7 2.400 1.735 49.8
7 93.198 (variable)
8 92.995 1.800 1.750 35.3
9 34.391 4.274 1.816 46.6
10 44.216 7.528
11 -180.117 1.700 1.528 76.5
12 121.148 0.484
13 65.973 5.511 1.789 28.4
14 1359.812 2.721
15 -105.632 1.500 1.497 81.5
16 399.221 (variable)
17 178.567 3.256 1.497 81.5
18 -1602.05 0.136
19 58.361 5.561 1.497 81.5
20 400.782 19.982
21 (aperture) ∞ 0.500
22 75.552 3.042 1.497 81.5
23 174.59 8.414
24 -270.101 2.000 1.695 42.2
25 48.432 2.417
26 92.105 1.800 1.800 29.8
27 64.222 6.992 1.497 81.5
28 -136.344 0.150
29 96.638 2.687 1.816 46.6
30 330.341 1.000
31 40.329 4.723 1.497 81.5
32 484.054 (variable)
33 415.075 2.862 1.893 20.4
34 -144.135 1.300 1.852 40.8
35 53.349 2.000
36 1181.562 2.000 1.852 40.8
37 65.624 (Variable)
38(Ext) 46.084 3.731 1.497 81.5
39(Ext) -272.994 1.907
40(Ext) 18.946 4.984 1.517 52.4
41(Ext) 52.322 1.150 1.883 40.8
42(Ext) 18.591 7.882
43(Ext) -205.37 0.950 1.905 35.0
44(Ext) 27.464 6.147 1.738 32.3
45(Ext) -51.367 0.950 1.804 46.6
46(Ext) 117.778 0.369
47(Ext) 54.679 7.768 1.613 44.3
48(Ext) -22.944 1.050 1.595 67.7
49 (Ext) 159.66 (Variable)
50 75.851 14.180 1.603 38.0
51 -46.623 1.980 1.808 22.8
52 -74.984 28.545
53 -52.714 1.981 1.729 54.7
54 -198.68 (variable)
Image plane ∞

Wide-angle end, Mid-range, Telephoto end
d 7 3.802 39.570 72.602
d16 56.962 27.574 0.979
d32 3.329 2.974 0.419
d37 8.410 8.764 11.319
d49 13.108 13.108 13.108
d54 39.993 39.993 39.993

Wide-angle end, intermediate, telephoto end: Focal length 278.7, 385.4, 522.5
F-number 5.5 5.5 5.5
Half-angle 4.44 3.21 2.37
Image height 21.635 21.635 21.635
Lens length: 367.18 373.56 380.00
BF 39.993 39.993 39.993

The numerical values of the conditional expressions in each numerical example are summarized in Table 1 below.

(Imaging device)
Next, with reference to Figure 18, an imaging device equipped with the optical system of each embodiment will be described. Figure 18 is a schematic diagram of an imaging device (digital still camera) 10 using any of the optical systems 1a to 1f of Embodiments 1 to 6 as the imaging optical system.

In Figure 18, 13 is the camera body, and 11 is the imaging optical system (interchangeable lens) composed of one of the optical systems 1a to 1f from Examples 1 to 6. 12 is an image sensor (photoelectric conversion element), such as a CCD sensor or CMOS sensor, built into the camera body 13, which receives light from the imaging optical system 11 (the optical image formed by the imaging optical system 11) and converts it into photoelectric energy. The camera body 13 may be a so-called single-lens reflex camera with a quick-turn mirror, or a so-called mirrorless camera without a quick-turn mirror.

According to each embodiment, it is possible to provide a compact, high-performance zoom lens and imaging device that allows for the insertion of extender groups.

Although preferred embodiments of the present invention have been described above, the present invention is not limited to these embodiments, and various modifications and changes are possible within the scope of its essence.

For example, the zoom lens in each embodiment consists of five lens groups other than the extender group EXT, but it is not limited to this; there may be six or more lens groups other than the extender group EXT.

1a-1f Optical system (zoom lens)
B1 First lens group B2 Second lens group B3 Third lens group B4 Fourth lens group B5 Fifth lens group EXT Extender group

Claims (9)

A zoom lens consisting of a first lens group with positive refractive power, a second lens group with negative refractive power, a third lens group with positive refractive power, a fourth lens group with negative refractive power, an extender group, and a fifth lens group with positive refractive power, arranged sequentially from the object side to the image side, wherein the spacing between adjacent lens groups changes during zooming.
The focal length of the zoom lens changes as the extender group is inserted into or removed from the optical path.
The second lens group has at least four lenses,
The extender group has a cemented lens,
When the focal length of the first lens group is f1, the focal length of the zoom lens at its telephoto end is ft, the distance along the optical axis from the fifth lens group to the fourth lens group when in focus at the telephoto end is D, the distance along the optical axis from the lens surface closest to the object to the image plane when in focus at the telephoto end is TL, the focal length of the third lens group is f3, and the focal length of the fourth lens group is f4,
0.60<f1/ft<1.50
-3.90<f1/f2<-1.00
0.10<D/TL<0.30
-5.00<f3/f4<-1.00
A zoom lens characterized by satisfying the following conditional equation. The zoom lens according to claim 1, characterized in that the fifth lens group remains stationary during zooming. -0.50<f4/ft<-0.05
A zoom lens according to claim 1 or 2, characterized in that it satisfies the following conditional expression. The zoom lens according to any one of claims 1 to 3, characterized in that the fifth lens group comprises at least one positive lens and at least one negative lens. The zoom lens according to any one of claims 1 to 4, characterized in that the fifth lens group comprises a cemented lens formed by joining a positive lens and a negative lens, and a negative lens positioned on the image side of the cemented lens. 0.10<f5/ft<2.00
A zoom lens according to any one of claims 1 to 5, characterized in that it satisfies the following conditional expression. A zoom lens according to any one of claims 1 to 6, characterized in that the fourth lens group moves during focusing. A zoom lens according to any one of claims 1 to 7, characterized in that the second lens group moves toward the image side when zooming from the wide-angle end to the telephoto end. An imaging device characterized by having a zoom lens according to any one of claims 1 to 8, and an image sensor that receives an image formed by the zoom lens.