Zoom lens and image pickup apparatus having zoom lens

Abstract

Zoom lenses and image pickup apparatuses having the zoom lenses are disclosed. A zoom lens can include, in order from an object side to an image side, a front group, an intermediate group, and a rear group, each of which includes one or more lens units. Each distance between adjacent lens units can change during zooming. The front group can consist of a first front lens unit having positive refractive power. The first front lens unit can be fixed with respect to an image plane during zooming. The intermediate group can consist, in order from the object side to the image side, of a first intermediate lens unit having negative refractive power, a second intermediate lens unit having negative refractive power, and a third intermediate lens unit. The third intermediate lens unit can move from the object side to the image side during zooming from a wide-angle end to a telephoto end. A predetermined inequality is satisfied.

Description

Technical Field

[0001] This disclosure relates to zoom lenses and image acquisition devices having zoom lenses. Background Technology

[0002] Modern zoom lenses are required to have reduced size, high zoom ratio, and the ability to satisfactorily correct various aberrations and perform high-speed zoom operations. Summary of the Invention

[0003] According to one aspect of this disclosure, a zoom lens may sequentially comprise a front group, a middle group, and a rear group from the object side to the image side, each of the front, middle, and rear groups comprising one or more lens units. The distance between each adjacent lens unit can be changed during zooming. The front group may consist of a first front lens unit having positive refractive power. The first front lens unit can be fixed relative to the image plane during zooming. The middle group may sequentially comprise a first intermediate lens unit having negative refractive power, a second intermediate lens unit having negative refractive power, and a third intermediate lens unit from the object side to the image side. During zooming from the wide-angle end to the telephoto end, the third intermediate lens unit can move from the object side to the image side. The following inequalities can be satisfied:

[0004]

[0005] Where fLF1 is the focal length of the first front lens unit, TLM1 is the distance on the optical axis from the lens surface closest to the object in the first intermediate lens unit to the lens surface closest to the image plane in the first intermediate lens unit, TLM2 is the distance on the optical axis from the lens surface closest to the object in the second intermediate lens unit to the lens surface closest to the image plane in the second intermediate lens unit, and MLM1 is the amount of movement of the first intermediate lens unit during zooming from the wide-angle end to the telephoto end, wherein the amount of movement towards the object side is positive. An image pickup device having the above-described zoom lens also constitutes another aspect of this disclosure.

[0006] The features of this disclosure will become clear from the following description of embodiments with reference to the accompanying drawings. The following description of embodiments is by way of example. Attached Figure Description

[0007] Figure 1 This is a cross-sectional view of the zoom lens according to Example 1, in the focused state at the wide-angle end for an object at infinity.

[0008] Figure 2A This is the aberration diagram of the zoom lens according to Example 1, under the focusing state of an object at infinity at the wide-angle end, and... Figure 2B This is the aberration diagram of the zoom lens according to Example 1, under the focusing state of an object at infinity at the telephoto end.

[0009] Figure 3 This is a cross-sectional view of the zoom lens according to Example 2, in the focusing state of an object at infinity at the wide-angle end.

[0010] Figure 4A This is the aberration diagram of the zoom lens according to Example 2, under the focusing state of an object at infinity at the wide-angle end, and... Figure 4B This is the aberration diagram of the zoom lens according to Example 2, under the focusing state of an object at infinity at the telephoto end.

[0011] Figure 5 This is a cross-sectional view of the zoom lens according to Example 3, in the focusing state of an object at infinity at the wide-angle end.

[0012] Figure 6A This is the aberration diagram of the zoom lens according to Example 3, under the focusing state of an object at infinity at the wide-angle end, and... Figure 6B This is the aberration diagram of the zoom lens according to Example 3, under the focusing state of an object at infinity at the telephoto end.

[0013] Figure 7 This is a cross-sectional view of the zoom lens according to Example 4, in the focusing state of an object at infinity at the wide-angle end.

[0014] Figure 8A This is the aberration diagram of the zoom lens according to Example 4, under the focusing state of an object at infinity at the wide-angle end, and... Figure 8B This is the aberration diagram of the zoom lens according to Example 4, under the focusing state of an object at infinity at the telephoto end.

[0015] Figure 9 This is a cross-sectional view of the zoom lens according to Example 5, in the focusing state of an object at infinity at the wide-angle end.

[0016] Figure 10A This is the aberration diagram of the zoom lens according to Example 5, under the focusing state of an object at infinity at the wide-angle end, and... Figure 10B This is the aberration diagram of the zoom lens according to Example 5, under the focusing state of an object at infinity at the telephoto end.

[0017] Figure 11 This is a cross-sectional view of the zoom lens according to Example 6, in the focusing state of an object at infinity at the wide-angle end.

[0018] Figure 12A This is the aberration diagram of the zoom lens according to Example 6, under the focusing state of an object at infinity at the wide-angle end, and... Figure 12BThis is the aberration diagram of the zoom lens according to Example 6, under the focusing state of an object at infinity at the telephoto end.

[0019] Figure 13 This is a schematic diagram of an image pickup device. Detailed Implementation

[0020] A detailed description of embodiments according to the present disclosure will now be given with reference to the accompanying drawings. Corresponding elements in the various figures will be designated by the same reference numerals, and repeated descriptions thereof will be omitted.

[0021] Figure 1 , Figure 3 , Figure 5 , Figure 7 , Figure 9 and Figure 11 This is a cross-sectional view of the zoom lens according to Examples 1 to 6 in a focused state at the wide-angle end for an object at infinity (hereinafter referred to as "focus state at infinity"). The zoom lens L0 according to each example is used in image acquisition devices such as digital video cameras, digital still cameras, broadcast cameras, film-based cameras, surveillance cameras, and vehicle-mounted (in-vehicle) cameras.

[0022] In each cross-sectional view, the left side is the object side and the right side is the image side. The zoom lens L0, according to each example, can also be used as a projection lens for a projector, etc. In this case, the left side is the image side and the right side is the projected image side.

[0023] The zoom lens L0 according to each example includes multiple lens units. In this specification, a lens unit refers to a group of lenses that move as a unit or remain stationary during zooming (magnification change). That is, in the zoom lens L0 according to each example, the distance between each adjacent lens unit changes during zooming. A lens unit may consist of one or more lenses. A lens unit may also include an aperture stop.

[0024] According to each example, the zoom lens L0 consists of a front group LF, a middle group LM and a rear group LR from the object side to the image side, and each group includes at least one lens unit.

[0025] In each cross-sectional view, LFi represents the i-th lens unit (where i is a natural number) counted from the object side in the front group LF. LMi represents the i-th lens unit (where i is a natural number) counted from the object side in the middle group LM. LRi represents the i-th lens unit (where i is a natural number) counted from the object side in the rear group LR.

[0026] SP represents the aperture stop, which defines (limits) the beam at the maximum F-number (Fno). I represents the image plane, where the imaging surface of an image sensor (photoelectric conversion element), such as a CCD sensor or a CMOS sensor, is deployed when the zoom lens L0 according to each example is used as the imaging optics system of a digital still camera or digital video camera. When the zoom lens according to each example is used as the imaging optics system of a film-based camera, the photosensitive surface equivalent to the film surface is deployed on the image plane I.

[0027] The solid arrows indicate the movement trajectory of each lens unit during zooming from the wide-angle end to the telephoto end. During focusing from an object at infinity to the nearest object, the lens unit (focusing unit) moves as indicated by the arrow labeled FOCUS.

[0028] Figure 2A , Figure 2B , Figure 4A , Figure 4B , Figure 6A , Figure 6B , Figure 8A , Figure 8B , Figure 10A , Figure 10B , Figure 12A and Figure 12B These are aberration diagrams of the zoom lens L0 according to Examples 1 to 6, in a focused state at infinity. In each aberration diagram, Figure 2A , Figure 4A , Figure 6A , Figure 8A , Figure 10A and Figure 12A It is the aberration map at the wide-angle end, and Figure 2B , Figure 4B , Figure 6B , Figure 8B , Figure 10B and Figure 12B It is an aberration diagram at the telescope.

[0029] In the spherical aberration diagram, Fno represents the F-number. The spherical aberration diagram indicates the amount of spherical aberration with respect to the d-line (wavelength 587.56 nm) and the g-line (wavelength 435.8 nm). In the astigmatism diagram, S indicates the amount of astigmatism in the sagittal plane with respect to the d-line, and M indicates the amount of astigmatism in the meridional plane with respect to the d-line. The distortion diagram indicates the amount of distortion with respect to the d-line. The chromatic aberration diagram indicates the amount of chromatic aberration with respect to the g-line. ω is the half-angle of view [°] calculated paraxially.

[0030] The following describes the feature configuration of the zoom lens L0 for each example.

[0031] The front element LF consists of a first front lens unit LF1 with positive refractive power. During zooming, the first front lens unit LF1 is fixed relative to the image plane. Maintaining the first front lens unit LF1 (which tends to have a relatively large lens diameter and mass) fixed during zooming facilitates high-speed zoom operation.

[0032] The intermediate lens group LM consists of the first intermediate lens unit LM1, the second intermediate lens unit LM2, and the third intermediate lens unit LM3, sequentially from the object side to the image side.

[0033] The following is a description of the configurations that can be satisfied by the zoom lens L0 for each example.

[0034] During zooming from the wide-angle end to the telephoto end, the third intermediate lens unit LM3 can be moved from the object side to the image side. This makes it easier to reduce the diameter and weight of the third intermediate lens unit LM3 and achieve high-speed zoom operation.

[0035] The first rear lens unit LR1, which is positioned closest to the object among the lens units included in the rear group LR, can have positive refractive power. This makes it easier to reduce the overall length and size.

[0036] During zooming, the first rear lens unit LR1 can be fixed relative to the image plane. As a result, the mechanism can be simplified and its size can be reduced.

[0037] The first rear lens unit LR1 may include an aperture stop SP. Therefore, optimal aberration correction before and after the aperture stop SP can be appropriate, and high image quality can be achieved.

[0038] Among the lens units included in the rear group LR, the second rear lens unit LR2, which is adjacent to the first rear lens unit LR1 and deployed on its image side, can move during zooming. This allows for proper correction of aberrations in the rear group LR and makes it easier to achieve high image quality.

[0039] The second rear lens unit LR2 can be moved during focusing. Placing the lens unit that moves during focusing on the image side (where the lens diameter is relatively small) provides a simple mechanism and reduces size.

[0040] The second rear lens unit LR2 can have negative refractive power. The rear group LR with a telephoto configuration can easily reduce the overall length.

[0041] The lens unit closest to the image plane can be fixed relative to the image plane during zooming. Fixing a lens with a relatively large diameter near the image plane relative to the image plane during zooming provides a simple mechanism and reduces size.

[0042] During focusing, the front group LF and the middle group LM can be fixed relative to the image plane. Fixing the object-side lens with a relatively large lens diameter relative to the image plane during focusing provides a simple mechanism and reduces size.

[0043] The first rear lens unit LR1 can have a positive lens deployed closest to the object. This allows for a telescopic configuration and makes it easier to reduce the overall length.

[0044] A description of the conditions that can be satisfied by the zoom lens L0 for each example will be given. One or more of the following inequalities (1) to (15) can be satisfied by the zoom lens for each example:

[0045]

[0046]

[0047] Here, fLF1 is the focal length of the first front lens unit LF1. TLM1 is the thickness of the first intermediate lens unit LM1, that is, the distance along the optical axis from the lens surface (surface vertex) closest to the object in the first intermediate lens unit LM1 to the lens surface (surface vertex) closest to the image plane in the first intermediate lens unit LM1. TLM2 is the thickness of the second intermediate lens unit LM2, that is, the distance along the optical axis from the lens surface (surface vertex) closest to the object in the second intermediate lens unit LM2 to the lens surface (surface vertex) closest to the image plane in the second intermediate lens unit LM2. ft is the focal length of the zoom lens L0 in the focusing state at infinity at the telephoto end. fw is the focal length of the zoom lens L0 in the focusing state at infinity at the wide-angle end. fLM1 is the focal length of the first intermediate lens unit LM1. fLM2 is the focal length of the second intermediate lens unit LM2. fLM3 is the focal length of the third intermediate lens unit LM3. fLR1 is the focal length of the first rear lens unit LR1. MLM1 is the amount of movement of the first intermediate lens unit LM1 during zoom from the wide-angle end to the telephoto end (where the movement towards the object side is positive). MLM2 is the amount of movement of the second intermediate lens unit LM2 during zoom from the wide-angle end to the telephoto end (where the movement towards the object side is positive). MLM3 is the amount of movement of the third intermediate lens unit LM3 during zoom from the wide-angle end to the telephoto end (where the movement towards the object side is positive). It is the combined horizontal magnification of the rear group LR at the wide-angle end. It is the combined lateral magnification of the rear group LR at the telescope end. BFw is the combined lateral magnification of the intermediate group LM at the telephoto end. BFw is the back focal length at infinity at the wide-angle end. Back focal length is the distance from the image-side lens surface (surface vertex) of the lens closest to the image plane among lenses of focal power to the optical axis of the image plane. In cases where there is a plate or similar element between the lens closest to the image plane and the image plane, the distance is calculated using air equivalent conversion. Lt is the distance from the object-side lens surface (surface vertex) to the optical axis of the image plane at infinity at the telephoto end.

[0048] Inequality (1) defines the appropriate thickness of the first intermediate lens unit LM1. When the thickness of the first intermediate lens unit LM1 increases and TLM1 / fLF1 becomes higher than the upper limit of inequality (1), the mass of the first intermediate lens unit LM1 increases, and it becomes difficult to achieve high-speed zoom operation. When the thickness of the first intermediate lens unit LM1 decreases and TLM1 / fLF1 becomes lower than the lower limit of inequality (1), it becomes difficult to correct various aberrations, especially astigmatism at the telephoto end.

[0049] Inequality (2) defines the appropriate thickness of the second intermediate lens unit LM2. When the thickness of the second intermediate lens unit LM2 increases and TLM2 / fLF1 becomes higher than the upper limit of inequality (2), it becomes difficult to achieve high-speed zoom operation. When the thickness of the second intermediate lens unit LM2 decreases and TLM2 / fLF1 becomes lower than the lower limit of inequality (2), it becomes difficult to correct various aberrations, especially astigmatism at the telephoto end.

[0050] Inequality (3) defines the appropriate relationship between the focal length of the zoom lens L0 and the focal length of the first front lens unit LF1 in a focused state at infinity at the telephoto end. When fLF1 / ft becomes higher than the upper limit of inequality (3), it becomes difficult to reduce the total length, and the size of the zoom lens L0 increases. When fLF1 / ft becomes lower than the lower limit of inequality (3), it becomes difficult to correct various aberrations, especially chromatic aberration at the telephoto end.

[0051] Inequality (4) defines the appropriate relationship between the focal length of the zoom lens L0 and the focal length of the first intermediate lens unit LM1 in a focused state at infinity at the wide-angle end. When fw / fLM1 becomes higher than the upper limit of inequality (4), it becomes difficult to achieve a high magnification ratio. When fw / fLM1 becomes lower than the lower limit of inequality (4), it becomes difficult to correct various aberrations, especially spherical aberration at the telephoto end.

[0052] Inequality (5) defines the appropriate relationship between the focal length of the zoom lens L0 and the focal length of the second intermediate lens unit LM2 in a focused state at infinity at the wide-angle end. When fw / fLM2 becomes higher than the upper limit of inequality (5), it becomes difficult to achieve a high magnification ratio. When fw / fLM2 becomes lower than the lower limit of inequality (5), it becomes difficult to correct various aberrations, especially spherical aberration at the telephoto end.

[0053] Inequality (6) defines the appropriate relationship between the focal length of the zoom lens L0 and the focal length of the third intermediate lens unit LM3 when focusing on an object at infinity at the wide-angle end. When fw / fLM3 becomes higher than the upper limit of inequality (6), it becomes difficult to correct various aberrations, especially spherical aberration at the telephoto end. When fw / fLM3 becomes lower than the lower limit of inequality (6), the size of the zoom lens L0 increases.

[0054] Inequality (7) defines the appropriate relationship between the focal length of the zoom lens L0 and the focal length of the first rear lens unit LR1 in a focused state at infinity at the wide-angle end. When fw / fLR1 becomes higher than the upper limit of inequality (7), it becomes difficult to correct various aberrations, especially spherical aberration at the telephoto end. When fw / fLR1 becomes lower than the lower limit of inequality (7), the size of the zoom lens L0 increases.

[0055] Inequality (8) defines the appropriate relationship between the amount of movement of the first intermediate lens unit LM1 and the focal length of the first front lens unit LF1 during zooming from the wide-angle end to the telephoto end. When MLM1 / fLF1 becomes higher than the upper limit of inequality (8), the size of the zoom lens L0 increases. When MLM1 / fLF1 becomes lower than the lower limit of inequality (8), it becomes difficult to achieve high magnification changes.

[0056] Inequality (9) defines the appropriate relationship between the amount of movement of the second intermediate lens unit LM2 and the focal length of the first front lens unit LF1 during zooming from the wide-angle end to the telephoto end. When MLM2 / fLF1 becomes higher than the upper limit of inequality (9), the size of the zoom lens L0 increases. When MLM2 / fLF1 becomes lower than the lower limit of inequality (9), it becomes difficult to achieve high magnification changes.

[0057] Inequality (10) defines the appropriate relationship between the amount of movement of the third intermediate lens unit LM3 and the focal length of the first front lens unit LF1 during zooming from the wide-angle end to the telephoto end. When MLM3 / fLF1 becomes higher than the upper limit of inequality (10), the size of the zoom lens L0 increases. When MLM3 / fLF1 becomes lower than the lower limit of inequality (10), it becomes difficult to achieve high magnification changes.

[0058] Inequality (11) defines the appropriate combination lateral magnification of the rear group LR at the wide-angle end. When the value exceeds the upper limit of inequality (11), it becomes difficult to correct various aberrations, especially field curvature at the optical end. When the value falls below the lower limit of inequality (11), it becomes difficult to correct various aberrations, especially the field curvature at the optical end.

[0059] Inequality (12) defines the appropriate relationship between the combined lateral magnification of the rear LR group at the wide-angle end and the combined lateral magnification of the rear LR group at the telephoto end. When the value exceeds the upper limit of inequality (12), it becomes difficult to correct various aberrations, especially field curvature at the telescope. When the value falls below the lower limit of inequality (12), it becomes difficult to achieve high-rate changes.

[0060] Inequality (13) defines the appropriate combined lateral magnification of the intermediate group LM at the telephoto end. If the focal length becomes higher than the upper limit of inequality (13), the focal length at the telephoto end becomes too short. When the aberrations fall below the lower limit of inequality (13), it becomes difficult to correct various aberrations, especially astigmatism at the telescope.

[0061] Inequality (14) defines the appropriate relationship between the back focal length at infinity at the wide-angle end and the focal length of the zoom lens L0 at infinity at the wide-angle end. When the back focal length increases and BFw / fw becomes higher than the upper limit of inequality (14), the size of the zoom lens L0 increases. When the back focal length decreases and BFw / fw becomes lower than the lower limit of inequality (14), the diameter of the back lens increases.

[0062] Inequality (15) defines the appropriate relationship between the distance along the optical axis from the lens surface closest to the object to the image plane in a focused state at infinity at the telephoto end and the focal length of the zoom lens L0 in a focused state at infinity at the telephoto end. When Lt / ft becomes higher than the upper limit of inequality (15), the size of the zoom lens L0 increases. When Lt / ft becomes lower than the lower limit of inequality (15), it becomes difficult to correct various aberrations, especially field curvature at the telephoto end.

[0063] The lower limit of inequality (1) can be set to 0.0015, 0.0020, 0.0025, 0.0030, 0.0035, 0.0040, 0.0042, 0.0044, 0.0046 or 0.0048. The upper limit of inequality (1) can be set to 0.0240, 0.0230, 0.0225, 0.0220, 0.0215, 0.0210, 0.0205, 0.0200, 0.0195 or 0.0190.

[0064] The lower limit of inequality (2) can be set to 0.0015, 0.0020, 0.0025, 0.0030, 0.0035, 0.0040, 0.0042, 0.0044, 0.0046, or 0.0048. The upper limit of inequality (2) can be set to 0.0218, 0.0216, 0.0214, 0.0212, 0.0210, 0.0209, 0.0208, 0.0207, 0.0206, or 0.0205.

[0065] The lower limit of inequality (3) can be set to 0.22, 0.25, 0.28, 0.31, 0.34, 0.37, 0.39, 0.40, 0.41 or 0.42. The upper limit of inequality (3) can be set to 2.00, 1.80, 1.60, 1.40, 1.30, 1.20, 1.16, 1.13, 1.10 or 1.08.

[0066] The lower limit of inequality (4) can be set to -3.2, -3.0, -2.8, -2.6, -2.4, -2.2, -2.1, -2.0, -1.9 or -1.8. The upper limit of inequality (4) can be set to -0.35, -0.40, -0.45, -0.50, -0.55, -0.57, -0.59, -0.61, -0.63 or -0.65.

[0067] The lower limit of inequality (5) can be set to -4.1, -3.9, -3.7, -3.5, -3.3, -3.1, -2.9, -2.7, -2.5 or -2.3. The upper limit of inequality (5) can be set to -0.22, -0.24, -0.25, -0.26, -0.27, -0.28, -0.29, -0.30, -0.31 or -0.32.

[0068] The lower limit of inequality (6) can be set to -2.6, -2.4, -2.2, -2.0, -1.9, -1.8, -1.7, -1.6, -1.5, or -1.4. The upper limit of inequality (6) can be set to 2.2, 2.0, 1.9, 1.8, 1.7, 1.6, 1.5, 1.4, 1.3, or 1.2.

[0069] The lower limit of inequality (7) can be set to 0.80, 1.00, 1.05, 1.10, 1.15, 1.20, 1.25, 1.30, 1.35 or 1.40. The upper limit of inequality (7) can be set to 7.4, 7.0, 6.6, 6.2, 5.8, 5.4, 5.0, 4.6, 4.2 or 3.8.

[0070] The lower limit of inequality (8) can be set to 0.110, 0.120, 0.125, 0.130, 0.135, 0.140, 0.145, 0.150, 0.155 or 0.158. The upper limit of inequality (8) can be set to 0.75, 0.70, 0.65, 0.60, 0.55, 0.50, 0.45, 0.40, 0.39 or 0.38.

[0071] The lower limit of inequality (9) can be set to 0.110, 0.116, 0.118, 0.120, 0.122, 0.124, 0.126, 0.128, 0.130, or 0.132. The upper limit of inequality (9) can be set to 0.75, 0.70, 0.65, 0.60, 0.55, 0.50, 0.45, 0.40, 0.39, or 0.38.

[0072] The lower limit of inequality (10) can be set to 0.101, 0.103, 0.104, 0.105, 0.106, 0.107, 0.108, 0.109, 0.110, or 0.111. The upper limit of inequality (10) can be set to 0.55, 0.50, 0.45, 0.40, 0.36, 0.35, 0.34, 0.33, 0.32, or 0.31.

[0073] The lower limit of inequality (11) can be set to -2.4, -2.2, -2.0, -1.9, -1.8, -1.7, -1.6, -1.5, -1.4 or -1.3. The upper limit of inequality (11) can be set to -0.21, -0.24, -0.27, -0.30, -0.33, -0.36, -0.39, -0.42, -0.45 or -0.48.

[0074] The lower limit of inequality (12) can be set to 0.35, 0.40, 0.45, 0.50, 0.55, 0.56, 0.57, 0.58, 0.59 or 0.60. The upper limit of inequality (12) can be set to 2.5, 2.3, 2.1, 2.0, 1.9, 1.8, 1.7, 1.6, 1.5 or 1.4.

[0075] The lower limit of inequality (13) can be set to -8.5, -8.0, -7.5, -7.0, -6.5, -6.0, -5.5, -5.0, -4.7 or -4.5. The upper limit of inequality (13) can be set to -0.55, -0.60, -0.65, -0.70, -0.75, -0.80, -0.85, -0.90, -0.95 or -1.00.

[0076] The lower limit of inequality (14) can be set to 0.110, 0.120, 0.130, 0.140, 0.150, 0.160, 0.170, 0.180, 0.185, or 0.190. The upper limit of inequality (14) can be set to 1.00, 0.90, 0.80, 0.70, 0.66, 0.64, 0.62, 0.60, 0.58, or 0.56.

[0077] The lower limit of inequality (15) can be set to 0.35, 0.40, 0.44, 0.48, 0.50, 0.52, 0.54, 0.56, 0.57 or 0.58. The upper limit of inequality (15) can be set to 3.0, 2.8, 2.6, 2.4, 2.2, 2.0, 1.9, 1.8, 1.7 or 1.6.

[0078] Next, the zoom lens L0 will be described in detail for each example.

[0079] According to Example 1, the zoom lens L0 consists of a front group LF, a middle group LM, and a rear group LR, sequentially from the object side to the image side, with each group including one or more lens units. The front group LF consists of a first front lens unit LF1 with positive refractive power. During zooming, the first front lens unit LF1 is fixed relative to the image plane. The middle group LM consists of a first intermediate lens unit LM1 with negative refractive power, a second intermediate lens unit LM2 with negative refractive power, and a third intermediate lens unit LM3 with positive refractive power, sequentially from the object side to the image side. During zooming from the wide-angle end to the telephoto end, the first intermediate lens unit LM1, the second intermediate lens unit LM2, and the third intermediate lens unit LM3 move from the object side to the image side. The rear group LR consists of a first rear lens unit LR1 to a fifth rear lens unit LR5, with positive refractive power, negative refractive power, positive refractive power, negative refractive power, and negative refractive power, respectively, sequentially from the object side to the image side. During zooming, the first rear lens unit LR1 is fixed relative to the image plane. The first rear lens unit LR1 includes an aperture stop. The second rear lens unit LR2 moves during zooming. During focusing from infinity to near distance, the second rear lens unit LR2 moves towards the image side. During zooming, the third rear lens unit LR3 is fixed relative to the image plane. The fourth rear lens unit LR4 moves during zooming. During focusing from infinity to near distance, the fourth rear lens unit LR4 moves towards the image side. During zooming, the fifth rear lens unit LR5 is fixed relative to the image plane.

[0080] According to each of Examples 2 to 5, the zoom lens L0 is composed of a front group LF, a middle group LM, and a rear group LR from the object side to the image side, each group including one or more lens units. The front group LF consists of a first front lens unit LF1 with positive refractive power. During zooming, the first front lens unit LF1 is fixed relative to the image plane. The middle group LM consists of a first intermediate lens unit LM1 with negative refractive power, a second intermediate lens unit LM2 with negative refractive power, and a third intermediate lens unit LM3 with positive refractive power, starting from the object side. During zooming from the wide-angle end to the telephoto end, the first intermediate lens unit LM1, the second intermediate lens unit LM2, and the third intermediate lens unit LM3 move from the object side to the image side. The rear group LR consists of a first rear lens unit LR1 to a third rear lens unit LR3 with positive, negative, and positive refractive powers, respectively, starting from the object side to the image side. During zooming, the first rear lens unit LR1 is fixed relative to the image plane. The first rear lens unit LR1 includes an aperture stop. The second rear lens unit LR2 moves during zooming. During focusing from infinity to near distance, the second rear lens unit LR2 moves toward the image side. During zooming, the third rear lens unit LR3 remains fixed relative to the image plane.

[0081] According to Example 6, the zoom lens L0 consists of a front group LF, a middle group LM, and a rear group LR, sequentially from the object side to the image side, with each group including one or more lens units. The front group LF consists of a first front lens unit LF1 with positive refractive power. During zooming, the first front lens unit LF1 is fixed relative to the image plane. The middle group LM consists of a first intermediate lens unit LM1 with negative refractive power, a second intermediate lens unit LM2 with negative refractive power, and a third intermediate lens unit LM3 with negative refractive power, sequentially from the object side to the image side. During zooming from the wide-angle end to the telephoto end, the first intermediate lens unit LM1, the second intermediate lens unit LM2, and the third intermediate lens unit LM3 move from the object side to the image side. The rear group LR consists of a first rear lens unit LR1 to a third rear lens unit LR3 with positive, negative, and positive refractive powers, respectively, sequentially from the object side to the image side. During zooming, the first rear lens unit LR1 is fixed relative to the image plane. The first rear lens unit LR1 includes an aperture stop. The second rear lens unit LR2 moves during zooming. During focusing from infinity to near distance, the second rear lens unit LR2 moves toward the image side. During zooming, the third rear lens unit LR3 remains fixed relative to the image plane.

[0082] In the zoom lens L0 according to Examples 1 to 6, all surfaces with refractive forces are refractive surfaces. Compared to lenses composed of diffractive optical elements or reflective surfaces, it can easily achieve optical performance equal to or better than that of lenses composed of diffractive optical elements or reflective surfaces, and is less difficult to manufacture.

[0083] In the zoom lens L0 according to Examples 1 to 6, optical elements such as prisms that bend the light path are not used. Prisms and the like that bend the light path increase the thickness of the lens and make it difficult to reduce its size.

[0084] The descriptions of the numerical values ​​corresponding to Examples 1 through 6 will now be given.

[0085] In the surface data for each numerical example, r represents the radius of curvature of each optical surface, and d (mm) represents the axial distance (distance along the optical axis) between the m-th surface and the (m+1)-th surface, where m is the surface number counted from the light incident side. nd represents the refractive index of each optical element with respect to the d-line, and This represents the Abbe number of each optical element with respect to the d-line. The Abbe number of the material. The following statement is made:

[0086]

[0087] Nd, NF, and NC are the refractive indices of the d-line (587.6 nm), F-line (486.1 nm), and C-line (656.3 nm) in Fraunhofer.

[0088] In each numerical example, d, focal length (mm), F-number, and half angle of view (°) are values ​​based on the zoom lens L0 for each example in focus on an object at infinity. "Back focal length (BF)" is the distance along the optical axis from the last surface of zoom lens L0 (the lens surface closest to the image plane) to the paraxial image plane, expressed as the equivalent length in air. "Total lens length" is the distance along the optical axis from the foremost surface of zoom lens L0 (the lens surface closest to the object) to the last surface, plus the back focal length. WIDE indicates the wide-angle end, MIDDLE indicates the intermediate zoom position, and TELE indicates the telephoto end.

[0089] When the optical surface is aspherical, an asterisk * is added to the right of the surface number. The shape of an aspherical surface is described below:

[0090]

[0091] Where X is the displacement from the vertex of the surface in the direction of the optical axis, H is the height from the optical axis in the direction orthogonal to the optical axis, R is the paraxial radius of curvature, K is the conic constant, and A4, A5, A6, A7, A8, A9, A10, A11 and A12 are the aspheric coefficients of each order.

[0092] In each aspherical coefficient, "e±XX" represents "×10". ±XX ".

[0093] Numerical Example 1

[0094] Unit: mm

[0095] Surface data

[0096]

[0097]

[0098]

[0099] Aspherical data

[0100] Surface 14

[0101]

[0102] Surface 15

[0103]

[0104] Surface 23

[0105]

[0106] Surface 35

[0107]

[0108] Surface 36

[0109]

[0110] Various data

[0111]

[0112]

[0113] Zoom lens unit data

[0114]

[0115] Zoom lens unit data

[0116]

[0117] Single lens data

[0118]

[0119] Numerical Example 2

[0120] Unit: mm

[0121] Surface data

[0122]

[0123]

[0124]

[0125]

[0126] Various data

[0127]

[0128]

[0129] Zoom lens unit data

[0130]

[0131] Zoom lens unit data

[0132]

[0133] Single lens data

[0134]

[0135]

[0136]

[0137] Numerical Example 3

[0138] Unit: mm

[0139] Surface data

[0140]

[0141]

[0142]

[0143] Various data

[0144]

[0145]

[0146] Zoom lens unit data

[0147]

[0148] Zoom lens unit data

[0149]

[0150] Single lens data

[0151]

[0152]

[0153] Numerical Example 4

[0154] Unit: mm

[0155] Surface data

[0156]

[0157]

[0158] Various data

[0159]

[0160]

[0161] Zoom lens unit data

[0162]

[0163] Zoom lens unit data

[0164]

[0165] Single lens data

[0166]

[0167] Numerical Example 5

[0168] Unit: mm

[0169] Surface data

[0170]

[0171]

[0172]

[0173] Various data

[0174]

[0175]

[0176] Zoom lens unit data

[0177]

[0178] Zoom lens unit data

[0179]

[0180] Single lens data

[0181]

[0182] Numerical Example 6

[0183] Unit: mm

[0184] Surface data

[0185]

[0186]

[0187] Various data

[0188]

[0189]

[0190] Zoom lens unit data

[0191]

[0192] Zoom lens unit data

[0193]

[0194] Single lens data

[0195]

[0196] Table 1 below summarizes the various values ​​for each numerical example.

[0197] Table 1

[0198]

[0199] Image pickup device

[0200] Now for reference Figure 13 An example of a digital still camera (image pickup device) using the zoom lens L0 according to this disclosure as its imaging optics will be given. Figure 13 In the figures, reference numeral 10 denotes the camera body, and reference numeral 11 denotes an imaging optical system including any of the zoom lenses L0 according to Examples 1 to 6. The imaging optical system 11 and the camera body 10 may be integrated or separable. Reference numeral 12 denotes a solid-state image sensor (photoelectric conversion element), such as a CCD sensor or a CMOS sensor, built into the camera body 10, which receives the optical image formed by the imaging optical system 11 and performs photoelectric conversion. The camera body 10 may be a so-called single-lens reflex camera with a fast-rotating mirror, or a so-called mirrorless camera without a fast-rotating mirror.

[0201] Applying the zoom lens L0 according to this disclosure to an image acquisition device such as a digital still camera can provide an image acquisition device with a compact lens.

[0202] Although this disclosure has been described with reference to examples, it should be understood that this disclosure is not limited to the disclosed examples. The scope of the following claims should be given the broadest interpretation in order to cover all such modifications and equivalent structures and functions.

Claims

1. A zoom lens, comprising, from the object side to the image side: The front group, the middle group, and the rear group, each of which includes one or more lens units. Its characteristic is that the distance between each adjacent lens unit changes during zooming. The front group is composed of a first front lens unit with positive refractive power. The first front lens unit is fixed relative to the image plane during zooming. The intermediate group, from the object side to the image side, consists of a first intermediate lens unit with negative refractive power, a second intermediate lens unit with negative refractive power, and a third intermediate lens unit. The third intermediate lens unit moves from the object side to the image side during zooming from the wide-angle end to the telephoto end, and The following inequalities are satisfied: Where fLF1 is the focal length of the first front lens unit, TLM1 is the distance on the optical axis from the lens surface closest to the object in the first intermediate lens unit to the lens surface closest to the image plane in the first intermediate lens unit, TLM2 is the distance on the optical axis from the lens surface closest to the object in the second intermediate lens unit to the lens surface closest to the image plane in the second intermediate lens unit, and MLM1 is the amount of movement of the first intermediate lens unit during zooming from the wide-angle end to the telephoto end, wherein the amount of movement towards the object side is positive.

2. The zoom lens according to claim 1, characterized in that, The first rear lens unit, which is the closest to the object among the lens units included in the rear group, has positive refractive power.

3. The zoom lens according to claim 1, characterized in that, The first rear lens unit, which is the closest to the object among the lens units included in the rear group, is fixed relative to the image plane during zooming.

4. The zoom lens according to claim 1, characterized in that, The first rear lens unit, which is the closest to the object among the lens units in the rear group, includes an aperture stop.

5. The zoom lens according to claim 1, characterized in that, A second rear lens unit, positioned on the image side of the first rear lens unit and adjacent to the first rear lens unit, moves during zooming. The first rear lens unit is positioned closest to the object among the lens units included in the rear group.

6. The zoom lens according to claim 1, characterized in that, A second rear lens unit, positioned on the image side of the first rear lens unit and adjacent to the first rear lens unit, moves during focusing. The first rear lens unit is positioned closest to the object among the lens units included in the rear group.

7. The zoom lens according to claim 1, characterized in that, The second rear lens unit, which is positioned on the image side of the first rear lens unit and adjacent to the first rear lens unit, has a negative refractive power. The first rear lens unit is positioned closest to the object among the lens units included in the rear group.

8. The zoom lens according to claim 1, characterized in that, The lens unit closest to the image plane is fixed relative to the image plane during zooming.

9. The zoom lens according to claim 1, characterized in that, The front group and the middle group are fixed relative to the image plane during focusing.

10. The zoom lens according to claim 1, characterized in that, The first rear lens unit, which is the closest to the object among the lens units included in the rear group, has the positive lens that is closest to the object.

11. The zoom lens according to claim 1, characterized in that, The following inequalities are satisfied: Where ft is the focal length of the zoom lens in the focusing state when focusing on an object at infinity at the telephoto end.

12. The zoom lens according to claim 1, characterized in that, The following inequalities are satisfied: Where fw is the focal length of the zoom lens in the focusing state at the wide-angle end for an object at infinity, and fLM1 is the focal length of the first intermediate lens unit.

13. The zoom lens according to claim 1, characterized in that, The following inequalities are satisfied: Where fw is the focal length of the zoom lens in the focusing state at the wide-angle end for an object at infinity, and fLM2 is the focal length of the second intermediate lens unit.

14. The zoom lens according to claim 1, characterized in that, The following inequalities are satisfied: Where fw is the focal length of the zoom lens in the focusing state at the wide-angle end for an object at infinity, and fLM3 is the focal length of the third intermediate lens unit.

15. The zoom lens according to claim 1, characterized in that, The following inequalities are satisfied: Where fw is the focal length of the zoom lens in the focusing state at the wide-angle end for an object at infinity, and fLR1 is the focal length of the first rear lens unit deployed closest to the object among the lens units included in the rear group.

16. The zoom lens according to claim 1, characterized in that, The following inequalities are satisfied: MLM2 is the amount of movement of the second intermediate lens unit during zooming from the wide-angle end to the telephoto end, wherein the amount of movement toward the object side is positive.

17. The zoom lens according to claim 1, characterized in that, The following inequalities are satisfied: MLM3 is the amount of movement of the third intermediate lens unit during zooming from the wide-angle end to the telephoto end, wherein the amount of movement toward the object side is positive.

18. The zoom lens according to claim 1, characterized in that, The following inequalities are satisfied: in It is the combined lateral magnification of the latter group at the wide-angle end.

19. The zoom lens according to claim 1, characterized in that, The following inequalities are satisfied: in It is the combined lateral magnification of the latter group at the wide-angle end, and It is the combined lateral magnification of the rear group at the telescope end.

20. The zoom lens according to claim 1, characterized in that, The following inequalities are satisfied: in It is the combined lateral magnification of the intermediate group at the telescope end.

21. The zoom lens according to claim 1, characterized in that, The following inequalities are satisfied: Where BFw is the back focal length when focusing on an object at infinity at the wide-angle end, and fw is the focal length of the zoom lens when focusing on an object at infinity at the wide-angle end.

22. The zoom lens according to any one of claims 1 to 21, characterized in that, The following inequalities are satisfied: Where ft is the focal length of the zoom lens in the focusing state of an object at infinity at the telephoto end, and Lt is the distance on the optical axis from the lens surface closest to the object to the image plane in the focusing state of an object at infinity at the telephoto end.

23. A zoom lens, comprising, from the object side to the image side: The front group, the middle group, and the rear group, each of which includes one or more lens units. Its characteristic is that the distance between each adjacent lens unit changes during zooming. The front group is composed of a first front lens unit with positive refractive power. The first front lens unit is fixed relative to the image plane during zooming, and The intermediate group consists of a first intermediate lens unit with negative refractive power, a second intermediate lens unit with negative refractive power, and a third intermediate lens unit, sequentially from the object side to the image side.

24. An image acquisition device, comprising: The zoom lens according to any one of claims 1 to 23; as well as An image sensor that receives an optical image formed by the zoom lens.

Images