Zoom lens and image capturing device

Abstract

To provide a compact, high-performance zoom lens which allows an extender group to be inserted therein.SOLUTION: A zoom lens provided herein comprises a first lens group having positive refractive power, a second lens group having negative refractive power, a third lens group having positive refractive power, a fourth lens group having negative refractive power, and a fifth lens group having positive refractive power, arranged in order from the object side to the image side, and is configured such that distances between adjacent lens groups change while zooming. The zoom lens further comprises an extender group configured to be inserted to or removed from the light path to change the focal length of the zoom lens. The zoom lens satisfies given conditional expressions regarding; a focal length f1 of the first lens group; a focal length ft of the zoom lens at the telephoto end; an optical axial distance D from a final lens group located on the most image side to a lens group next to the final lens group when focused at infinity at the telephoto end; an optical axial distance TL from a lens surface on the most object side to the image plane when focused at infinity at the telephoto end; a focal length f3 of the third lens group; and a focal length f4 of the fourth lens group.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a zoom lens and an imaging device. [Background technology]

[0002] 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 or removed. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Patent No. 5409841 [Patent Document 2] Japanese Patent Application Publication No. 2019-120771 Summary of the Invention [Problem to be solved by the invention]

[0004] In the optical systems disclosed in Patent Documents 1 and 2, an extender is provided on the image side of the aperture stop for the purpose of compactness. In this case, it is necessary to ensure a wide spacing between the lens groups on the image side of the aperture stop, so the focus lens group needs to be located on the object side of the aperture stop. If the focus lens group is located on the object side of the aperture stop, the diameter of the focus lens group will be determined by the Fno light beam diameter at the telephoto end, which means that the diameter will be large and heavy, making it impossible to achieve high-speed operation.

[0005] SUMMARY OF THE INVENTION It is therefore an object of the present invention to provide a small, high-performance zoom lens and an image pickup apparatus into which an extender group can be inserted. [Means for solving the problem]

[0006] A zoom lens according to one aspect of the present invention comprises, in order from the object side to the image side, a first lens group having a positive refractive power, a second lens group having a negative refractive power, a third lens group having a positive refractive power, a fourth lens group having a negative refractive power, an extender group, and a fifth lens group having a positive refractive power, and the distance between adjacent lens groups changes during zooming, and the focal length of the zoom lens changes when the extender group is inserted or removed from the optical path, and the second lens group has at least four lenses, and the extender group The fifth lens group has a cemented lens, the lens in the first lens group closest to the object has positive refractive power, and 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 focusing on infinity at the telephoto end, the distance TL on the optical axis from the lens surface closest to the object to the image plane when focusing on infinity at the telephoto end, the focal length f3 of the third lens group, and the focal length f4 of the fourth lens group satisfy predetermined conditional expressions.

[0007] Other objects and features of the present invention are illustrated in the following examples. [Effects of the Invention]

[0008] According to the present invention, it is possible to provide a small-sized, high-performance zoom lens and an image pickup apparatus into which an extender group can be inserted. [Brief explanation of the drawings]

[0009] [Figure 1] FIG. 2 is a cross-sectional view of the first embodiment at the wide-angle end. [Figure 2] 1A and 1B are aberration diagrams in Example 1 at the wide-angle end, at the intermediate zoom position, and at the telephoto bridge position, respectively. [Figure 3] FIG. 10 is a cross-sectional view of the wide-angle end in the second embodiment. [Figure 4] 10A to 10C are aberration diagrams in Example 2 at (a) the wide-angle end, (b) an intermediate zoom position, and (c) a telephoto bridge. [Figure 5] FIG. 10 is a cross-sectional view of the wide-angle end in the third embodiment. [Figure 6]10A and 10B are aberration diagrams in Example 3 at (a) the wide-angle end, (b) an intermediate zoom position, and (c) a telephoto bridge. [Figure 7] FIG. 10 is a cross-sectional view of the fourth embodiment at the wide-angle end. [Figure 8] 10A to 10C are aberration diagrams in Example 4 at (a) the wide-angle end, (b) an intermediate zoom position, and (c) a telephoto bridge. [Figure 9] FIG. 10 is a cross-sectional view of the fifth embodiment at the wide-angle end. [Figure 10] 10A to 10C are aberration diagrams in Example 5 at (a) the wide-angle end, (b) an intermediate zoom position, and (c) a telephoto bridge. [Figure 11] FIG. 13 is a cross-sectional view of the sixth embodiment at the wide-angle end. [Figure 12] 10A to 10C are aberration diagrams in Example 6 at (a) the wide-angle end, (b) an intermediate zoom position, and (c) a telephoto bridge. [Figure 13] FIG. 10 is a cross-sectional view at the wide-angle end in Example 1-2. [Figure 14] FIG. 10 is a cross-sectional view at the wide-angle end in Example 3-2. [Figure 15] FIG. 4 is a cross-sectional view at the wide-angle end in Example 4-2. [Figure 16] FIG. 5 is a cross-sectional view at the wide-angle end in Example 5-2. [Figure 17] FIG. 10 is a cross-sectional view at the wide-angle end in Example 6-2. [Figure 18] 1 is a schematic diagram of an imaging device including an optical system in each embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0010] Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

[0011] 1, 3, 5, 7, 9, and 11 are cross-sectional views of optical systems (zoom lenses) 1a to 1f of Examples 1 to 6, respectively, when focused on infinity at the wide-angle end. The optical systems of the respective Examples 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.

[0012] In each cross-sectional view, the left side is the object side (the magnification conjugate plane side), and the right side is the image side (the reduction conjugate plane side). The optical system of each embodiment is composed of, from the object side to the image side, a first lens group B1, a second lens group B2, a third lens group B3, a fourth lens group B4, and a fifth lens group B5. In each embodiment, a lens group refers to a group of lenses that either move integrally or remain stationary during zooming. In the optical system of each embodiment, the spacing between adjacent lens groups changes during zooming from the wide-angle end to the telephoto end. The wide-angle end and the telephoto end represent zoom states in which the lens group that moves during zooming is located at both ends of its mechanically movable range along the optical axis OA (optical axis direction). Each lens group may be composed of a single lens or multiple lenses. The lens group may also include an aperture stop (aperture stop) SP.

[0013] The aperture stop SP determines (limits) the light flux at the maximum F-number (Fno). IP is an image plane (reduction conjugate plane), and 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 imaging element (photoelectric conversion element) such as a CCD sensor or CMOS sensor is disposed 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 disposed on the image plane IP.

[0014] In the optical system of each embodiment, when zooming from the wide-angle end to the telephoto end, each lens group moves as shown by the solid arrow in each cross-sectional view. When focusing from an object at infinity to the closest object, the fourth lens group (focus lens group) B4 moves as shown by the arrow focus.

[0015] 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 when the zoom lens is at the wide-angle end and focused at infinity, (B) shows the longitudinal aberration diagram when the zoom lens is at the intermediate zoom position and focused at infinity, and (C) shows the longitudinal aberration diagram when the zoom lens is at the telephoto end and focused at infinity.

[0016] In the spherical aberration diagram, Fno is the F-number, and the spherical aberration diagram shows the amount of spherical aberration for each of the d-line (wavelength 587.6 nm), g-line (wavelength 435.8 nm), C-line (wavelength 656.3 nm), and F-line (486.1 nm). In the astigmatism diagram, S shows the amount of astigmatism on the sagittal image plane, and M shows the amount of astigmatism on 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).

[0017] Next, the characteristic configuration of the optical system (zoom lens) of each embodiment will be described. The optical system of each embodiment has, arranged 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. Furthermore, the spacing between adjacent lens groups changes during zooming. The optical system of each embodiment also has a magnification conversion optical group (extender group EXT) that is inserted into or removed from the optical path to change the focal length of the zoom lens.

[0018] In each embodiment, the first lens unit B1 satisfies the following conditional expression (1).

[0019] 0.60 <f1 / ft<1.50 ···(1) In conditional formula (1), f1 is the focal length of the first lens unit B1, and ft is the focal length of the optical system at the telephoto end. Exceeding the upper limit of conditional formula (1) weakens the power (refractive power) of the first lens unit B1. As a result, it is not possible to reduce the size of the optical system at the telephoto end, or to increase the focal length at the telephoto end. On the other hand, falling below the lower limit of conditional formula (1), the power of the first lens unit B1 becomes too strong. While this is effective in increasing the focal length at the telephoto end, the excessively strong power increases the amount of spherical aberration at the telephoto end, and increases distortion and lateral chromatic aberration throughout the entire zoom range.

[0020] In each embodiment, the first lens unit B1 and the second lens unit B2 satisfy the following conditional expression (2).

[0021] -3.90 <f1 / f2<-0.10 ···(2) In conditional expression (2), f2 is the focal length of the second lens unit B2. If the upper limit of conditional expression (2) is exceeded, the power of the second lens unit B2 becomes too weak, the amount of movement required to achieve a predetermined amount of magnification increases, and the optical system becomes long. On the other hand, if the lower limit of conditional expression (2) is not reached, the power of the second lens unit B2 becomes too strong, and although the amount of movement required to achieve a predetermined amount of magnification can be shortened, lateral chromatic aberration at the wide-angle end cannot be suppressed, and spherical aberration and axial chromatic aberration at the telephoto end cannot be suppressed.

[0022] The optical system of each embodiment also satisfies the following conditional expressions (3) and (4).

[0023] 0.10 <D / TL<0.30 ···(3) -5.00 <f3 / f4<-1.00 ···(4) In conditional formula (3), D is the distance on the optical axis from the final lens group (fifth lens group B5) closest to the image to the lens group (fourth lens group B4) adjacent to the final lens group when focusing at infinity at the telephoto end. TL is the distance on the optical axis from the lens surface closest to the object to the image plane IP when focusing at infinity at the telephoto end. In conditional formula (4), f3 is the focal length of the third lens group B3, and f4 is the focal length of the fourth lens group B4.

[0024] If the upper limit of conditional expression (3) is exceeded, the air gap containing the extender group will be too wide, which will make the distance from the first lens group B1 to the fourth lens group B4, which have the main image-forming function, too short, and will require the power of each lens group to be strong, making it difficult to correct various aberrations or increasing the number of lenses in each lens group in order to effectively suppress various aberrations, resulting in increased costs.

[0025] On the other hand, if the lower limit of conditional expression (3) is exceeded, the air gap containing the extender group becomes too narrow, the size required for the extender group becomes too small, and the aberrations of the extender group cannot be suppressed, or an aspherical lens must be used to effectively suppress the aberrations of the extender group, which increases costs.

[0026] If the upper limit of conditional expression (4) is exceeded, the power of the third lens group B3 becomes too strong relative to the power of the fourth lens group B4. Having a strong power in the third lens group B3 has the advantage of being able to compress the light beam incident on the subsequent fourth lens group B4, thereby reducing the weight of the fourth lens group B4. However, if the upper limit of conditional expression (4) is exceeded, the power of the third lens group B3 becomes too strong, causing excessive spherical aberration and axial chromatic aberration at the wide-angle end. Furthermore, if an attempt is made to suppress this with the third lens group B3, a large number of lenses would be required, which would increase the weight and cost of the optical system.

[0027] On the other hand, if the lower limit of conditional expression (4) is not reached, 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 becomes too weak, the light beam incident on the subsequent fourth lens group B4 cannot be compressed, and the fourth lens group B4, which serves as a focus lens group, must have a large diameter. As the diameter of the fourth lens group B4 increases, its weight increases and high-speed operation becomes difficult. Furthermore, it becomes more difficult to focus the light beam, which results in a longer optical system. To prevent this, if power is added to the fifth lens group B5, which serves as the final lens group, in an attempt to focus light, the ray angle of off-axial rays also changes sharply, resulting in increased chromatic aberration of magnification.

[0028] In the optical systems of each embodiment, the final lens unit (fifth lens unit B5) is fixed (it does not move during zooming). This is because, if a built-in extender insertion / removal mechanism is provided in the space immediately in front of the final lens unit, it would be difficult to configure the units with the same cam across the built-in extender.

[0029] Preferably, the optical system of each embodiment satisfies the following conditional expression (5):

[0030] -0.50 <f4 / ft<-0.05 ···(5) If the lower limit of conditional expression (5) is exceeded, the power of the fourth lens group B4 becomes too weak. If the power of the fourth lens group B4, which is a focus lens group, becomes weak, a large movement distance during focusing must be ensured, resulting in an increase in the size of the optical system or a narrow focusing range. On the other hand, if the upper limit of conditional expression (5) is exceeded, the power of the fourth lens group B4 becomes too strong. If the power of the fourth lens group B4 becomes strong, there is the advantage that the group movement distance during focusing can be shortened, but it is necessary to increase the number of lenses in the fourth lens group B4 to suppress aberration fluctuations during focusing, which increases the weight of the fourth lens group B4.

[0031] Preferably, the optical system of each embodiment satisfies the following conditional expression (6):

[0032] 0.10 <f5 / ft<2.00 ···(6) In conditional expression (6), f5 is the focal length of the fifth lens group B5. If the upper limit of conditional expression (6) is exceeded, the power of the fifth lens group B5 becomes too weak. The fifth lens group B5 has the role of focusing the light beam emerging from the fourth lens group B4 onto the sensor surface (on the image plane IP) while adjusting the image surface size, and also has the function of canceling out distortion that could not be fully suppressed by the first lens group B1. If the power of the fifth lens group B5 becomes too weak, distortion cannot be canceled out. On the other hand, if the lower limit of conditional expression (6) is not reached, 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 becomes large, and even if the distortion generated in the first lens group B1 is canceled out, distortion will still occur within the fifth lens group B5.

[0033] More preferably, the numerical ranges of conditional expressions (1) to (6) are set so as to satisfy the following conditional expressions (1a) to (6b).

[0034] 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 so as to satisfy the following conditional expressions (1b) to (6b).

[0035] 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 system of each embodiment will be described. [Example]

[0036] First, an optical system 1a in Example 1 will be described with reference to FIG. 1. The optical system 1a in this Example is a telephoto zoom lens. As shown in FIG. 1, the optical system 1a is composed 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 so that a magnification conversion optical group (extender group) can be inserted or removed. The second lens group B2 and the fourth lens group B4 move during zooming. The second lens group B2 mainly has a magnification changing function, while the fourth lens group B4 has a function of correcting the focus position that moves during magnification changing.

[0037] The first lens group B1 contributes to compressing the overall optical system at the telephoto end. It remains fixed (unmoving) during zooming and is designed to enhance dust- and splash-proof performance, enhancing durability in adverse weather conditions. It consists of a first lens element with positive refractive power, a second lens element with positive refractive power, a third lens element with positive refractive power, and a fourth lens element with negative refractive power. The third and fourth lenses are cemented together. The first and second lenses are given strong light-gathering properties, and the air gap between the second and third lenses is increased, allowing for a smaller diameter for the third lens element. Reducing the number of focusing lenses in the first and second lenses to a single lens would result in increased spherical aberration at the telephoto end. In addition, the cemented lens formed by the third and fourth lenses has a composite focal length with negative power, and has the function of canceling out spherical aberration occurring between the first and second lenses at the telephoto end, and also has the function of canceling out distortion occurring between the first and second lenses over the entire zoom range.

[0038] The second lens group B2 moves from the object side (magnification conjugate direction) to the image side (reduction conjugate direction) from the wide-angle end to the telephoto end, so that the main imaging performance is provided to the third lens group B3 at the wide-angle end and the first lens group B1 at the telephoto end. The lens diameter of the second lens group B2 is determined by off-axis marginal rays at the wide-angle end or on-axis marginal rays at the telephoto end. In this case, off-axis marginal rays at the wide-angle end are sufficiently converged by the first lens group B1, so the diameter of the second lens group B2 does not need to be increased. On-axis marginal rays at the telephoto end are sufficiently converged by the second lens group B2 moving toward the reduction conjugate plane, so the diameter of the second lens group B2 does not need to be increased.

[0039] However, if the second lens unit B2 has positive refractive power, it moves from the reduction conjugate surface side to the magnification conjugate surface side during zooming from the wide-angle end to the telephoto end. At this time, the lens diameter of the second lens unit B2 is determined by the height of the on-axis marginal ray at the telephoto end, resulting in a large diameter and heavy weight. Furthermore, a single convex lens with positive refractive power is provided as the fourth lens in the second lens unit B2. This makes it easier to align the image plane with the second lens unit B2, which has negative refractive power. Furthermore, three lenses with negative refractive power are provided in the second lens unit B2. This gently bends off-axial rays at the wide-angle end, thereby suppressing various aberrations. It is preferable that the second lens unit B2 have at least four lenses.

[0040] The third lens unit B3 contributes to compressing the entire optical system at the wide-angle end, and a low-dispersion convex lens is used to suppress axial chromatic aberration. In this embodiment, the third lens unit B3 does not move during zooming, but it may be moved during zooming to suppress aberration fluctuations.

[0041] The fourth lens group is a variable magnification lens group that moves during zooming, and is also a focus lens group that moves from the magnification conjugate direction to the reduction conjugate direction from infinity to the close-up end during focusing, forming an image of the light beam on the sensor surface. In this embodiment, a cemented lens is provided in the focus lens group, which is configured to easily suppress chromatic aberration even when the power of the lens group is strong.

[0042] The fifth lens group B5 is a field lens that focuses light emitted from the fourth lens group B4 onto the image sensor surface. In this embodiment, by arranging a negative lens closest to the reduction conjugate plane, it is possible to satisfy the angle of incidence condition on the image sensor. Furthermore, by providing an air gap between the negative lens and the positive lens immediately preceding it in the fifth lens group B5, the height of off-axis light rays incident on the positive lens is increased, thereby canceling distortion generated by the negative lens. In this case, the positive lens is a cemented lens to prevent light rays from separating by color through the air. That is, the final lens group (fifth lens group B5) is composed of a cemented lens formed by cementing a positive lens and a negative lens together, and a negative lens located on the image side of the cemented lens. The fifth lens group B5 also plays a role in canceling distortion that cannot be completely suppressed by the first lens group B1.

[0043] Figure 13 is a cross-sectional view of the optical system 1a of Figure 1 at the wide-angle end when focusing at infinity with the extender group EXT inserted. By inserting the extender group EXT between the fourth lens group B4 and the fifth lens group B5 of the optical system 1a of Figure 1, the focal length increases by approximately 1.4 times, making it possible to realize a more telephoto optical system. [Example]

[0044] Next, an optical system 1b in Example 2 will be described with reference to FIG. 2. The optical system 1b in this example differs from the optical system 1a in Example 1 in that the fifth lens group B5 has an aspherical lens. That is, the optical system 1b performs good image plane correction by providing an aspherical surface in the fifth lens group B5, where off-axis rays are separated. In this example, the aspherical surface is formed by bonding a resin material to glass, but the glass may have an aspherical shape. Furthermore, although the object to be bonded is a cemented lens, it may also be bonded to a single lens. [Example]

[0045] Next, an optical system 1c according to Example 3 will be described with reference to Fig. 5. The optical system 1c according to Example 3 has one less lens than the optical system 1b according to Example 2 that constitutes the fourth lens group B4, making it possible to drive at higher speeds.

[0046] Figure 14 is a cross-sectional view of the optical system 1c of 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 increases by approximately 1.4 times, making it possible to realize a more telephoto optical system. [Example]

[0047] Next, an optical system 1d according to Example 4 will be described with reference to Fig. 7. The optical system 1d of this Example has a telephoto end extended to the long focal length side compared to the optical system 1a of Example 1. This enables the range of expression to be further expanded.

[0048] Figure 15 is a cross-sectional view of the optical system 1d of 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 increases by approximately 1.4 times, making it possible to realize a more telephoto optical system. [Example]

[0049] Next, an optical system 1e in Example 5 will be described with reference to Fig. 9. The optical system 1e in this example differs from the optical system 1a in Example 1 in that the third lens unit B3 moves during zooming. By moving the third lens unit B3 during zooming, better aberration correction becomes possible.

[0050] Figure 16 is a cross-sectional view of the optical system 1e of 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 increases by approximately 1.4 times, making it possible to realize a more telephoto optical system. [Example]

[0051] Next, an optical system 1f in Example 6 will be described with reference to Fig. 11. The optical system 1f of this Example differs from the optical system 1a of Example 1 in that the first lens unit B1 moves during zooming. By moving the first lens unit B1 during zooming, better aberration correction is possible at the telephoto end.

[0052] Figure 17 is a cross-sectional view of the optical system 1f of 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 increases by approximately 1.4 times, making it possible to realize a more telephoto optical system.

[0053] Numerical Examples 1 to 6 corresponding to Examples 1 to 6, respectively, and Numerical Examples 1-2 and 3-2 to 6-2 corresponding to the states in which a magnification conversion optical group (extender group) is built in (inserted into) Examples 1 and 3 to 6, respectively, are shown below.

[0054] In the surface data of each numerical example, r represents the radius of curvature of each optical surface, and d (mm) represents the axial distance (distance on the optical axis) between the mth surface and the (m+1)th surface. Here, m is the surface number counted from the light incident side. Furthermore, nd represents the refractive index of each optical element with respect to the d-line, and vd represents the Abbe number of the optical element with respect to the d-line. The Abbe number vd is given by the following equation when the refractive indices at the d-line (587.6 nm), F-line (486.1 nm), and C-line (656.3 nm) of the Fraunhofer lines are Nd, NF, and NC, respectively: νd=(Nd-1) / (NF-NC) It is expressed as:

[0055] 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 (when focused at infinity). "Back focus" is the distance on the optical axis from the final lens surface (the lens surface closest to the image) to the paraxial image plane, expressed as an air-equivalent length. "Total lens length" is the distance on the optical axis from the forefront lens surface (the lens surface closest to the object) to the final lens surface plus the back focus. "Lens group" is not limited to cases where it is composed of multiple lenses, but also includes cases where it is composed of a single lens.

[0056] Furthermore, if the optical surface is aspherical, an asterisk (*) is added to the right of the surface number. The aspherical shape is expressed by the following equation, where x is the displacement from the vertex of the surface in the optical axis direction, h is the height from the optical axis in a direction perpendicular to the optical axis, R is the paraxial radius of curvature, k is the conic constant, and A4, A6, A8, A10, A12, and A14 are aspherical coefficients of each order.

[0057] 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 In addition, "e±XX" in each aspherical coefficient is "×10± XX " means.

[0058] (Numerical Example 1) Surface 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 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 58.493 58.870 61.479 d42 39.994 39.994 39.994 Wide-angle end Mid-range Telephoto end Focal length 206.1 285.0 385.5 F-number 4.1 4.1 4.1 Half angle of view 5.99 4.34 3.21 Image height 21.635 21.635 21.635 Lens total length 367.62 367.62 367.62 BF 39.994 39.994 39.994 (Numerical Example 2) Surface 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 (0 after c8) Wide-angle end Mid-range 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 Mid-range Telephoto end Focal length 206.4 309.0 383.7 F-number 4.1 4.1 4.1 Half angle of view 5.98 4.01 3.23 Image height 21.635 21.635 21.635 Lens total length 358.05 358.05 358.05 BF 39.983 39.983 39.983 (Numerical Example 3) Surface 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 (0 after c8) 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 64.037 65.641 69.158 d38 39.996 39.996 39.996 Wide-angle end Mid-range Telephoto end Focal length 207.5 309.0 380.8 F-number 4.1 4.1 4.1 Half angle of view 5.95 4.01 3.25 Image height 21.635 21.635 21.635 Lens total length 368.37 368.37 368.37 BF 39.996 39.996 39.996 (Numerical Example 4) Surface 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 Mid-range 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 Mid-range Telephoto end Focal length 207.0 306.0 487.9 F-number 4.1 4.1 4.1 Half angle of view 5.97 4.04 2.54 Image height 21.635 21.635 21.635 Lens total length 410.05 410.05 410.05 BF 39.998 39.998 39.998 (Numerical Example 5) Surface 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 Mid-range Telephoto end Focal length 200.1 309.0 386.1 F-number 4.1 4.1 4.1 Half angle of view 6.17 4.01 3.21 Image height 21.635 21.635 21.635 Lens total length 367.43 367.43 367.43 BF 39.997 39.997 39.997 (Numerical Example 6) Surface 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 Mid-range Telephoto end Focal length 206.1 285.0 386.5 F-number 4.1 4.1 4.1 Half angle of view 5.99 4.34 3.2 Image height 21.635 21.635 21.635 Lens total length 367.18 373.56 380.00 BF 39.993 39.993 39.993 (Numerical Example 1-2) Surface 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 Mid-range Telephoto end Focal length 290.4 401.6 543.2 F-number 5.8 5.8 5.8 Half angle of view 4.26 3.08 2.28 Image height 21.635 21.635 21.635 Lens total length 367.62 367.62 367.62 BF 39.994 39.994 39.994 (Numerical Example 3-2) Surface 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 (0 after c8) 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 Mid-range Telephoto end Focal length 295.9 440.8 543.2 F-number 5.9 5.8 5.9 Half angle of view 4.18 2.81 2.28 Image height 21.635 21.635 21.635 Lens total length 368.37 368.37 368.37 BF 39.995 39.995 39.995 (Numerical Example 4-2) Surface 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 Mid-range 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 Mid-range Telephoto end Focal length 288.1 425.7 678.9 F-number 5.7 5.7 5.7 Half angle of view 4.30 2.91 1.83 Image height 21.635 21.635 21.635 Lens total length 410.05 410.05 410.05 BF 39.998 39.998 39.998 (Numerical Example 5-2) Surface 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 Mid-range Telephoto end Focal length 278.4 429.9 537.2 F-number 5.7 5.7 5.7 Half angle of view 4.44 2.88 2.31 Image height 21.635 21.635 21.635 Lens total length 367.43 367.43 367.43 BF 39.997 39.997 39.997 (Numerical Example 6-2) Surface 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 Mid-range Telephoto end Focal length 278.7 385.4 522.5 F-number 5.5 5.5 5.5 Half angle of view 4.44 3.21 2.37 Image height 21.635 21.635 21.635 Lens total 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.

[0059] [Table 1]

[0060] (imaging device) Next, an imaging device including the optical system of each example will be described with reference to Fig. 18. Fig. 18 is a schematic diagram of an imaging device (digital still camera) 10 that uses any one of the optical systems 1a to 1f of Examples 1 to 6 as an imaging optical system.

[0061] 18, reference numeral 13 denotes a camera body, and 11 denotes an imaging optical system (interchangeable lens) configured using any one of the optical systems 1a to 1f of Examples 1 to 6. Reference numeral 12 denotes an imaging element (photoelectric conversion element) such as a CCD sensor or CMOS sensor that is built into camera body 13 and receives light from imaging optical system 11 (an optical image formed by imaging optical system 11) and performs photoelectric conversion. Camera body 13 may be a so-called single-lens reflex camera that has a quick-turn mirror, or a so-called mirrorless camera that does not have a quick-turn mirror.

[0062] According to each embodiment, it is possible to provide a small-sized, high-performance zoom lens and an imaging device into which an extender group can be inserted.

[0063] Although the 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 the gist of the present invention.

[0064] For example, the zoom lens in each embodiment is made up of five lens groups other than the extender group EXT, but this is not limitative, and the number of lens groups other than the extender group EXT may be six or more. [Explanation of symbols]

[0065] 1a~1f Optical system (zoom lens) B1 First lens group B2 Second lens group B3 Third lens group B4 4th lens group B5 5th lens group EXT Extender group

Claims

1. A zoom lens comprising, arranged in order from the object side to the image side, a first lens group having positive refractive power, a second lens group having negative refractive power, a third lens group having positive refractive power, a fourth lens group having negative refractive power, an extender group, and a fifth lens group having positive refractive power, 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, the second lens group has at least four lenses, the extender group includes a cemented lens; Let f1 be the focal length of the first lens group, ft be the focal length of the zoom lens at the telephoto end, D be the distance on the optical axis from the fifth lens group to the fourth lens group when focusing on infinity at the telephoto end, TL be the distance on the optical axis from the lens surface closest to the object to the image plane when focusing on infinity at the telephoto end, f3 be the focal length of the third lens group, and f4 be the focal length of the fourth lens group. 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 expressions:

2. 2. The zoom lens according to claim 1, wherein the fifth lens group remains stationary during zooming.

3. -0.50<f4 / ft<-0.05 3. The zoom lens according to claim 1, wherein the following condition is satisfied:

4. 4. The zoom lens according to claim 1, wherein the fifth lens group comprises at least one positive lens and at least one negative lens.

5. 5. The zoom lens according to claim 1, wherein the fifth lens group comprises a cemented lens formed by cementing a positive lens and a negative lens together, and a negative lens disposed on the image side of the cemented lens.

6. 0.10<f5 / ft<2.00 6. The zoom lens according to claim 1, wherein the following condition is satisfied:

7. 7. The zoom lens according to claim 1, wherein the fourth lens group moves during focusing.

8. 8. The zoom lens according to claim 1, wherein the second lens group moves toward the image side during zooming from the wide-angle end to the telephoto end.

9. 9. An imaging device comprising: the zoom lens according to claim 1; and an imaging element that receives an image formed by the zoom lens.

Images