JP6583574B2 - Zoom lens and imaging device - Google Patents

Description

  The present invention relates to a zoom lens and an imaging apparatus.

  Conventionally, a zoom lens having a small size and a short back focus has been proposed (see, for example, Patent Document 1).

JP 2009-251118 A

  However, conventional so-called standard zoom lenses have adopted a method of increasing the refractive power of each group in order to reduce the size. Therefore, there is a tendency to make the group configuration complicated or increase the number of components. In addition, when each group is configured with a strong power, the configuration tends to be highly sensitive to eccentricity, which has a drawback in assembling the lens. In addition, a lens type advantageous for correcting various aberrations has been demanded.

  The present invention has been made in view of such problems, and an object of the present invention is to provide a zoom lens and an imaging apparatus that are small in size, high in performance, and low in various aberrations.

  In order to achieve such an object, a zoom lens according to the first aspect of the present invention includes a first lens group having a positive refractive power and a second lens group having a negative refractive power, which are arranged in order from the object side. A lens group substantially consisting of four lens groups, a third lens group having a negative refractive power and a fourth lens group having a positive refractive power, and adjacent to the first to fourth lens groups. A part of the fourth lens group is provided as a vibration-proof lens group for correcting image blur so as to be movable so as to have a component perpendicular to the optical axis. And the following conditional expression is satisfied.

0.60 <f4 / fw <1.15
4.50 <f1 / f4 <11.00
However,
f1: the focal length of the first lens group,
f4: focal length of the fourth lens group,
fw: The focal length of the entire system in the wide-angle end state when focusing on infinity.

  The zoom lens according to a second aspect of the present invention includes a first lens group having a positive refractive power, a second lens group having a negative refractive power, and a third lens having a negative refractive power, which are arranged in order from the object side. It consists of substantially four lens groups, a lens group and a fourth lens group having a positive refractive power, and is changed by changing the air spacing between adjacent lens groups of the first to fourth lens groups. A part of the fourth lens group is provided as a vibration-proof lens group for correcting image blur so as to be movable so as to have a component perpendicular to the optical axis, and satisfies the following conditional expression: .

0.60 <f4 / fw <1.15
0.596 ≤ VRT <2.00
4.00 <f1 / f4 <11.00
However,
f1: the focal length of the first lens group,
f4: focal length of the fourth lens group,
fw: focal length of the entire system in the wide-angle end state when focusing on infinity,
VRT: Anti-vibration coefficient in the telephoto end state of the anti-vibration lens group.
The anti-vibration coefficient VRT is defined by the following conditional expression.
VRT = | (1-Bvr) × Br |
However,
Bvr: lateral magnification of the anti-vibration lens group,
Br: lateral magnification of the entire optical system on the image side from the image stabilizing lens group.

  A zoom lens according to a third aspect of the present invention includes a first lens group having a positive refractive power, a second lens group having a negative refractive power, and a third lens having a negative refractive power, which are arranged in order from the object side. It consists of substantially four lens groups, a lens group and a fourth lens group having a positive refractive power, and is changed by changing the air spacing between adjacent lens groups of the first to fourth lens groups. A part of the fourth lens group is provided as a vibration-proof lens group for correcting image blur so as to be movable so as to have a component perpendicular to the optical axis, and satisfies the following conditional expression: .

0.60 <f4 / fw <1.15
0.596 ≤ VRT ≤ 0.924
4.00 <f1 / f4 <11.00
However,
f1: the focal length of the first lens group,
f4: focal length of the fourth lens group,
fw: focal length of the entire system in the wide-angle end state when focusing on infinity,
VRT: Anti-vibration coefficient in the telephoto end state of the anti-vibration lens group.
The anti-vibration coefficient VRT is defined by the following conditional expression.
VRT = | (1-Bvr) × Br |
However,
Bvr: lateral magnification of the anti-vibration lens group,
Br: lateral magnification of the entire optical system on the image side from the image stabilizing lens group.

  A zoom lens according to a fourth aspect of the present invention includes a first lens group having a positive refractive power, a second lens group having a negative refractive power, and a third lens having a negative refractive power, which are arranged in order from the object side. It consists of substantially four lens groups, a lens group and a fourth lens group having a positive refractive power, and is changed by changing the air spacing between adjacent lens groups of the first to fourth lens groups. A part of the fourth lens group is provided as a vibration-proof lens group for correcting image blur so as to be movable so as to have a component in a direction perpendicular to the optical axis. It has one positive lens on the most image side, and has a cemented negative lens composed of a cemented positive lens and negative lens on its object side with a convex cemented surface facing the image side. Satisfies the equation.

0.60 <f4 / fw <1.15
0.10 <VRT ≦ 0.596
However,
f4: focal length of the fourth lens group,
fw: focal length of the entire system in the wide-angle end state when focusing on infinity,
VRT: Anti-vibration coefficient in the telephoto end state of the anti-vibration lens group.
The anti-vibration coefficient VRT is defined by the following conditional expression.
VRT = | (1-Bvr) × Br |
However,
Bvr: lateral magnification of the anti-vibration lens group,
Br: lateral magnification of the entire optical system on the image side from the image stabilizing lens group.

  The imaging device of the present invention includes any one of the zoom lenses described above.

  According to the present invention, it is possible to provide a zoom lens and an imaging apparatus that are small in size, high in performance, and low in various aberrations.

It is sectional drawing which shows the lens structure in the infinite point focusing state of the zoom lens which concerns on 1st Example. FIG. 4A is a diagram illustrating various aberrations when the zoom lens according to Example 1 is in focus at infinity in the wide-angle end state, FIG. 9A is a diagram illustrating various aberrations when focusing at infinity in the wide-angle end state, and FIG. FIG. 10 is a coma aberration diagram when performing blur correction (shift amount of the image stabilizing group = 0.332). FIG. 5 is a diagram illustrating various aberrations when the zoom lens according to Example 1 is in focus at infinity in the intermediate focal length state. FIG. 4A is a diagram illustrating various aberrations when the zoom lens according to Example 1 is in focus at infinity in the telephoto end state, FIG. 5A is a diagram illustrating various aberrations when focusing at infinity in the telephoto end state, and FIG. FIG. 10 is a coma aberration diagram when blur correction (shift amount of the image stabilizing group = 0.457) is performed. It is sectional drawing which shows the lens structure in the infinite point focusing state of the zoom lens which concerns on 2nd Example. FIG. 7A is a diagram illustrating various aberrations when the zoom lens according to Example 2 is in focus at infinity in the wide-angle end state, FIG. 9A is a diagram illustrating various aberrations when focusing at infinity in the wide-angle end state, and FIG. FIG. 10 is a coma aberration diagram when blur correction (shift amount of image stabilizing group = 0.733) is performed. FIG. 12 is a diagram illustrating various aberrations when the zoom lens according to Example 2 is focused at infinity in the intermediate focal length state. FIG. 6A is a diagram illustrating various aberrations when the zoom lens according to Example 2 is in focus at infinity in the telephoto end state, FIG. 9A is a diagram illustrating various aberrations when focusing at infinity in the telephoto end state, and FIG. FIG. 6 is a coma aberration diagram when blur correction (shift amount of image stabilizing group = 0.92) is performed. It is sectional drawing which shows the lens structure in the infinite point focusing state of the zoom lens which concerns on 3rd Example. FIG. 6A is a diagram illustrating various aberrations when the zoom lens according to Example 3 is in focus at infinity in the wide-angle end state, FIG. 9A is a diagram illustrating various aberrations when focusing at infinity in the wide-angle end state, and FIG. FIG. 10 is a coma aberration diagram when blur correction (shift amount of image stabilization group = 0.216) is performed. FIG. 11 is a diagram illustrating various aberrations when the zoom lens according to Example 3 is in focus at infinity in the intermediate focal length state. FIG. 6A is a diagram illustrating various aberrations when the zoom lens according to Example 3 is in focus at infinity in the telephoto end state, FIG. 9A is a diagram illustrating various aberrations when focusing at infinity in the telephoto end state, and FIG. FIG. 10 is a coma aberration diagram when blur correction (shift amount of image stabilization group = 0.295) is performed. It is sectional drawing which shows the lens structure in the infinite point focusing state of the zoom lens which concerns on 4th Example. FIG. 7A is a diagram illustrating various aberrations when the zoom lens according to Example 4 is in focus at infinity in the wide-angle end state, FIG. 9A is a diagram illustrating aberrations when focusing at infinity in the wide-angle end state, and FIG. FIG. 7 is a coma aberration diagram when blur correction (shift amount of image stabilization group = 0.168) is performed. FIG. 10 is a diagram illustrating various aberrations when the zoom lens according to Example 4 is in focus at infinity in the intermediate focal length state. FIG. 7A is a diagram illustrating various aberrations when the zoom lens according to Example 4 is in focus at infinity in the telephoto end state, FIG. 9A is a diagram illustrating various aberrations when focusing at infinity in the telephoto end state, and FIG. FIG. 10 is a coma aberration diagram when blur correction (shift amount of image stabilization group = 0.200) is performed. It is sectional drawing which shows the structure of the camera (imaging device) which concerns on this embodiment. 5 is a flowchart for explaining a method of manufacturing a zoom lens according to the present embodiment.

  Hereinafter, the present embodiment will be described with reference to the drawings. As shown in FIG. 1, the zoom lens ZL according to this embodiment includes a first lens group G1 having a positive refractive power, a second lens group G2 having a negative refractive power, arranged in order from the object side, It has a third lens group G3 having a negative refractive power and a fourth lens group G4 having a positive refractive power, and is changed by changing the air gap between the first lens group G1 and the second lens group G2. A part of the fourth lens group G4 is provided as a vibration-proof lens group (for example, the lens L41 in FIG. 1) for correcting image blur so as to be movable so as to have a component perpendicular to the optical axis. Therefore, the following conditional expression (1) is satisfied.

0.60 <f4 / fw <1.15 (1)
However,
f4: focal length of the fourth lens group G4,
fw: The focal length of the entire system in the wide-angle end state when focusing on infinity.

  Conditional expression (1) is a condition that defines the focal length of the positive fourth lens group G4, in other words, the magnitude relationship of the refractive power. The greatest feature of the present invention is that the refractive power of the fourth lens group G4 is particularly strong. As a result, the total optical length is significantly reduced, and downsizing can be achieved. Furthermore, by maintaining the category of the conditional expression (1), it is possible to correct various aberrations satisfactorily and optimally.

  When the upper limit value of conditional expression (1) is exceeded, the focal length of the fourth lens group G4 increases, that is, the refractive power decreases. In this case, the total optical length is increased and the back focus is also increased. Therefore, it becomes difficult to achieve a zoom lens that is remarkably miniaturized as in the present invention. In addition, if the refractive power of other groups, in particular, the first lens group G1 and the second lens group G2, is strengthened and the miniaturization is promoted, the field curvature and astigmatism change as a result. Variation due to magnification and correction of coma aberration deteriorate, which is not preferable.

  Note that by setting the upper limit value of conditional expression (1) to 1.10, it is possible to correct aberrations satisfactorily. Further, by setting the upper limit value of conditional expression (1) to 1.09, better aberration correction can be performed. Further, by setting the upper limit value of conditional expression (1) to 1.08, better aberration correction can be performed. Further, by setting the upper limit of conditional expression (1) to 1.07, the effect of this embodiment can be maximized.

  When the lower limit of conditional expression (1) is not reached, the focal length of the fourth lens group G4 becomes small, that is, the refractive power becomes strong. In this case, downsizing can be achieved, but the back focus is too short and the exit pupil is too close to the image plane. In addition, the degree of design difficulty increases in terms of aberration correction. As a result, fluctuation due to field curvature and astigmatism variation, spherical aberration and coma correction are deteriorated, distortion is increased, etc., which is not preferable. .

  In addition, by setting the lower limit value of conditional expression (1) to 0.63, it is possible to correct aberrations satisfactorily. Further, by setting the lower limit value of conditional expression (1) to 0.65, better aberration correction can be performed. Further, by setting the lower limit value of the conditional expression (1) to 0.70, further better aberration correction can be performed. Further, by setting the lower limit value of conditional expression (1) to 0.75, the effect of the present embodiment can be maximized.

  The zoom lens ZL according to the present embodiment also changes the air gap between the second lens group G2 and the third lens group G3 and the air gap between the third lens group G3 and the fourth lens group G4 during zooming. Is preferred. With this configuration, it is possible to ensure a predetermined zoom ratio while satisfactorily correcting mainly off-axis aberrations such as field curvature and coma.

  In the zoom lens ZL according to this embodiment, it is preferable that the following conditional expression (2) is satisfied.

0.10 <VRT <2.00 (2)
However,
VRT: Anti-vibration coefficient in the telephoto end state of the anti-vibration lens group.

  The anti-vibration coefficient VRT is defined by the following conditional expression.

VRT = | (1-Bvr) × Br |
However,
Bvr: lateral magnification of the anti-vibration lens group,
Br: lateral magnification of the entire optical system on the image side from the image stabilizing lens group (Note that Br = 1 when no optical element is present on the image side of the image stabilizing lens group).

  Conditional expression (2) is a condition that prescribes the anti-vibration coefficient of the anti-vibration lens group that is provided in the positive fourth lens group G4 so as to have a component perpendicular to the optical axis. It is. When the image stabilization coefficient is small, the amount of movement required for image stabilization per unit increases. When the image stabilization coefficient is large, the amount of movement required for image stabilization per unit decreases. .

  If the upper limit value of conditional expression (2) is exceeded, the anti-vibration coefficient becomes too large, and the stop control accuracy during anti-vibration must be remarkably increased, which is not preferable. In terms of aberration correction, coma aberration fluctuation and field curvature fluctuation during image stabilization increase, which is not preferable.

  Note that by setting the upper limit value of conditional expression (2) to 1.80, good aberration correction can be achieved. Further, by setting the upper limit value of conditional expression (2) to 1.60, better aberration correction can be performed. Further, by setting the upper limit value of conditional expression (2) to 1.50, it becomes possible to correct aberrations even better. Further, by setting the upper limit value of conditional expression (2) to 1.40, the effect of the present embodiment can be maximized.

  If the lower limit value of conditional expression (2) is not reached, the anti-vibration coefficient becomes too small, so that the amount of movement required for anti-vibration per unit increases remarkably. In this case, the size of the lens and the size of the vibration isolator are increased, which is not preferable. In terms of aberration correction, it is difficult to secure the light amount during image stabilization, and as a result, correction of coma aberration during image stabilization deteriorates.

  In addition, by setting the lower limit value of conditional expression (2) to 0.12, it becomes possible to correct aberrations satisfactorily. Further, by setting the lower limit value of conditional expression (2) to 0.15, better aberration correction can be performed. Further, by setting the lower limit value of conditional expression (2) to 0.17, better aberration correction can be performed. Further, by setting the lower limit value of conditional expression (2) to 0.20, it becomes possible to correct aberrations even better. Further, by setting the lower limit value of conditional expression (2) to 0.25, the effect of the present embodiment can be maximized.

  In the zoom lens ZL according to this embodiment, it is preferable that the following conditional expression (3) is satisfied.

3.00 <f1 / f4 <11.00 (3)
However,
f1: Focal length of the first lens group G1.

  Conditional expression (3) is a condition that defines the ratio between the focal lengths of the positive first lens group G1 and the positive fourth lens group G4, in other words, the magnitude relationship of the refractive power ratio.

  When the upper limit of conditional expression (3) is exceeded, the focal length of the fourth lens group G4 becomes smaller than the focal length of the first lens group G1, that is, the refractive power increases. In this case, fluctuation due to field curvature and astigmatism variation, correction of spherical aberration and coma aberration, deterioration of distortion, etc. occur, which is not preferable.

  Note that by setting the upper limit value of conditional expression (3) to 10.50, it becomes possible to correct aberrations satisfactorily. Further, by setting the upper limit value of conditional expression (3) to 10.00, better aberration correction becomes possible. Further, by setting the upper limit value of conditional expression (3) to 9.50, better aberration correction becomes possible. Further, by setting the upper limit value of conditional expression (3) to 9.00, the effect of the present embodiment can be maximized.

  When the lower limit value of conditional expression (3) is not reached, the focal length of the first lens group G1 is smaller than the focal length of the fourth lens group G4, that is, the refractive power is increased. In this case, correction of spherical aberration on the telephoto side and coma aberration in the entire area deteriorates, which is not preferable.

  Note that by setting the lower limit of conditional expression (3) to 3.20, it is possible to correct various aberrations satisfactorily. Further, by setting the lower limit value of conditional expression (3) to 3.50, it becomes possible to correct various aberrations better. Further, by setting the lower limit value of conditional expression (3) to 4.00, it becomes possible to correct various aberrations even better. Further, by setting the lower limit value of conditional expression (3) to 4.50, the effect of the present embodiment can be maximized.

  In the zoom lens ZL according to this embodiment, it is preferable that the following conditional expression (4) is satisfied.

0.10 <f2 / f3 <20.00 (4)
However,
f2: focal length of the second lens group G2,
f3: focal length of the third lens group G3.

  Conditional expression (4) is a condition that defines the ratio of the focal lengths of the negative second lens group G2 and the negative third lens group G3, in other words, the magnitude relationship of the refractive power ratio.

  When the upper limit value of conditional expression (4) is exceeded, the absolute value of the focal length of the third lens group G3 is smaller than the focal length of the second lens group G2, that is, the negative refractive power is increased. In this case, the amount of movement for focusing is small, but aberration fluctuations during focusing increase, and fluctuations due to field curvature and astigmatism scaling, as well as spherical aberration fluctuations, are undesirable.

  In addition, by setting the upper limit value of conditional expression (4) to 19.00, it becomes possible to correct aberrations satisfactorily. Further, by setting the upper limit value of conditional expression (4) to 18.50, better aberration correction becomes possible. Further, by setting the upper limit value of conditional expression (4) to 18.00, it is possible to correct aberrations even better. In addition, by setting the upper limit value of conditional expression (4) to 17.70, the effect of the present embodiment can be maximized.

  When the lower limit value of conditional expression (4) is not reached, the absolute value of the focal length of the second lens group G2 is smaller than the focal length of the third lens group G3, that is, the refractive power is increased. In this case, fluctuations due to coma aberration magnification, field curvature, and astigmatism fluctuations increase, which is not preferable.

  Note that by setting the lower limit of conditional expression (4) to 0.13, it is possible to correct aberrations satisfactorily. In addition, by setting the lower limit value of conditional expression (4) to 0.15, better aberration correction becomes possible. Further, by setting the lower limit value of the conditional expression (4) to 0.20, further better aberration correction can be performed. Further, by setting the lower limit value of conditional expression (4) to 0.22, the effect of the present embodiment can be maximized.

  In the zoom lens ZL according to the present embodiment, the fourth lens group G4 has one positive lens closest to the image side, and a positive cemented surface facing the image side toward the object side, It is preferable to have a cemented negative lens formed by cementing with a negative lens. With this configuration, the back focus is appropriately reduced, and the effect of shortening the total optical length is brought about. In terms of aberration correction, the configuration is more advantageous for correcting astigmatism, distortion, and coma.

  In the zoom lens ZL according to this embodiment, it is preferable that the following conditional expression (5) is satisfied.

0.10 <(-r) / fw <2.00 (5)
However,
r: radius of curvature of the cemented surface of the cemented negative lens in the fourth lens group G4.

  Conditional expression (5) is the optimum value of the radius of curvature of the cemented surface of the cemented negative lens in the negative fourth lens group G4 (for example, the cemented negative lens composed of the lenses L44 and L45 in FIG. 1). It is a condition that prescribes.

  When exceeding the upper limit value of the conditional expression (5), the radius of curvature of the cemented surface of the cemented negative lens in the negative fourth lens group G4 becomes large, and the surface refractive power becomes weak. In this case, negative distortion increases, which is not preferable.

  In addition, by setting the upper limit value of conditional expression (5) to 1.50, it becomes possible to correct aberrations satisfactorily. Further, by setting the upper limit value of conditional expression (5) to 1.00, better aberration correction can be performed. Further, by setting the upper limit value of conditional expression (5) to 0.70, it is possible to correct aberrations even better. Further, by setting the upper limit value of conditional expression (5) to 0.60, the effect of the present embodiment can be maximized.

  When falling below the lower limit value of conditional expression (5), the radius of curvature of the cemented surface of the cemented negative lens in the negative fourth lens group G4 becomes small, and the surface refractive power becomes strong. In this case, positive distortion is increased, and coma, field curvature, and astigmatism are deteriorated.

  In addition, by setting the lower limit value of conditional expression (5) to 0.13, it is possible to correct aberrations satisfactorily. Further, by setting the lower limit value of conditional expression (5) to 0.15, better aberration correction can be performed. Further, by setting the lower limit value of the conditional expression (5) to 0.18, further better aberration correction can be performed. Further, by setting the lower limit value of conditional expression (5) to 0.20, the effect of the present embodiment can be maximized.

  The zoom lens ZL according to this embodiment preferably satisfies the following conditional expression (6).

30.00 ° <ωw <80.00 ° (6)
However,
ωw: Half angle of view in the wide-angle end state.

  Conditional expression (6) is a condition that defines an optimum value of the angle of view in the wide-angle end state. By satisfying this conditional expression (6), coma aberration, distortion aberration, and field curvature can be favorably corrected while having a wide angle of view.

  Incidentally, by setting the upper limit value of conditional expression (6) to 77.00 °, it becomes possible to correct aberrations satisfactorily.

  Further, by setting the lower limit value of conditional expression (6) to 33.00 °, it is possible to correct aberrations satisfactorily. Further, by setting the lower limit value of conditional expression (6) to 36.00 °, better aberration correction can be performed.

  The zoom lens ZL according to this embodiment preferably satisfies the following conditional expression (7).

2.00 <ft / fw <15.00 (7)
However,
ft: The focal length of the entire system in the telephoto end state when focusing on infinity.

  Conditional expression (7) is a condition that prescribes an appropriate ratio between the focal length of the entire system in the telephoto end state and the focal length of the entire system in the wide-angle end state when focusing on infinity. By satisfying the conditional expression (7), a high zoom ratio can be obtained, and spherical aberration and coma aberration can be corrected well.

  Incidentally, by setting the upper limit value of conditional expression (7) to 10.00, it becomes possible to correct aberrations satisfactorily. Further, by setting the upper limit value of conditional expression (7) to 7.00, better aberration correction can be performed.

  Further, by setting the lower limit value of conditional expression (7) to 2.30, it becomes possible to correct aberrations satisfactorily. Further, by setting the lower limit value of conditional expression (7) to 2.50, better aberration correction can be performed. Further, by setting the lower limit value of conditional expression (7) to 2.70, it becomes possible to correct aberrations even better.

  According to the present embodiment as described above, it is possible to realize a zoom lens ZL that is suitable for an imaging apparatus such as a so-called mirrorless camera or a range finder camera, is small, has high performance, and has few aberrations.

  Next, a camera (imaging device) 1 including the above-described zoom lens ZL will be described with reference to FIG. As shown in FIG. 17, the camera 1 is an interchangeable lens camera (so-called mirrorless camera) provided with the zoom lens ZL described above as the photographing lens 2.

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

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

  The zoom lens ZL according to this embodiment mounted on the camera 1 as the photographic lens 2 is small, high-performance, and low in aberrations due to its characteristic lens configuration, as can be seen from each example described later. The lens is realized. Thereby, this camera 1 can implement | achieve an imaging device with a small size, high performance, and few aberrations.

  Next, a method for manufacturing the zoom lens ZL according to the present embodiment will be outlined with reference to FIG. First, a first lens group G1 having a positive refractive power, a second lens group G2 having a negative refractive power, and a third lens group having a negative refractive power, which are arranged in order from the object side in the lens barrel. Each lens is arranged so as to have G3 and a fourth lens group G4 having a positive refractive power (step S10). At this time, each lens is arranged so as to change the magnification by changing the air gap between the first lens group G1 and the second lens group G2 (step ST20). A part of the fourth lens group G4 is provided as a vibration-proof lens group for correcting image blur so as to be movable so as to have a component perpendicular to the optical axis (step ST30). Further, each lens is arranged so as to satisfy the following conditional expression (1) (step ST40).

0.60 <f4 / fw <1.15 (1)
However,
f4: focal length of the fourth lens group G4,
fw: The focal length of the entire system in the wide-angle end state when focusing on infinity.

  As an example of the lens arrangement in the present embodiment, as shown in FIG. 1, as a first lens group G1, a negative meniscus lens L11 having a convex surface facing the object side and a positive meniscus lens L12 are joined in order from the object side. A cemented positive lens is arranged. As the second lens group G2, a negative meniscus lens L21 having a convex surface facing the object side, a biconcave negative lens L22, and a positive meniscus lens L23 having a convex surface facing the object side are disposed in order from the object side. As the third lens group G3, a negative meniscus lens L31 having a concave surface facing the object side is disposed. As the fourth lens group G4, in order from the object side, a positive meniscus lens L41 (antivibration lens group) having a convex surface directed toward the image side, and a biconvex positive lens L42 and a biconcave negative lens L43 are cemented together. A cemented positive lens, an aperture stop S for determining an F number, a cemented negative lens formed by cementing a positive lens L44 having an aspheric surface on the object side, and a negative lens L45 having a concave surface on the object side, and the object side A positive meniscus lens L46 having a convex surface is disposed.

  According to the manufacturing method according to the present embodiment as described above, it is possible to obtain a zoom lens ZL that is suitable for an imaging apparatus such as a so-called mirrorless camera and a range finder camera, is small in size, has high performance, and has few aberrations. .

  Hereinafter, each example according to the present embodiment will be described with reference to the drawings. Tables 1 to 4 are shown below, but these are tables of specifications in the first to fourth examples.

  1, FIG. 5, FIG. 9 and FIG. 13 are cross-sectional views showing the configurations of zoom lenses ZL (ZL1 to ZL4) according to the respective examples. In the cross-sectional views of the zoom optical systems ZL1 to ZL4, the movement trajectory along the optical axis of each of the lens groups G1 to G4 when zooming from the wide-angle end state (W) to the telephoto end state (T) is indicated by an arrow. ing.

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

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

  In [Lens data] in the table, the surface number is the order of the optical surfaces from the object side along the direction in which the light beam travels, R is the radius of curvature of each optical surface, and D is the next optical surface from each optical surface (or The distance between surfaces on the optical axis to the image plane), nd is the refractive index of the material of the optical member with respect to the d-line, and νd is the Abbe number based on the d-line of the material of the optical member. Further, (variable) indicates a variable surface interval, “∞” of the radius of curvature indicates a plane or an aperture, and (aperture S) indicates an aperture aperture S. The refractive index of air (d-line) “1.000000” is omitted. When the optical surface is an aspherical surface, “*” is attached to the left side of the surface number, and the paraxial radius of curvature is indicated in the column of the radius of curvature R.

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

^{X (y) = (y 2} / R) / [1+ {1-κ (y 2 / R 2)} 1/2] + A4 × y 4 + A6 × y 6 + A8 × y 8 + A10 × y 10 ... (a)

In each group interval data in the table, f is the focal length of the entire lens system, β is the imaging magnification, D0 is the distance from the object surface to the first surface, and Di (where i is an integer) is the i-th surface. The variable interval of the (i + 1) th plane is shown. 1-POS is in focus at infinity in the wide-angle end state, 2-POS is in focus at infinity in the intermediate focal length state, 3-POS is in focus at infinity in the telephoto end state, and 4-POS is wide-angle When focusing at an intermediate distance in the end state, 5-POS when focusing at an intermediate distance in the intermediate focal length state, 6-POS when focusing at an intermediate distance in the telephoto end state, and 7-POS when focusing at a short distance in the wide-angle end state In this case, 8-POS indicates near focus in the intermediate focal length state, and 9-POS indicates close focus in the telephoto end state.

  In [Various data] in the table, f is the focal length of the entire lens system, FNO is the F number, ω is the half angle of view (unit: °), Y is the image height, TL is the total length of the lens system (on the optical axis) Σd is the distance from the lens front surface to the lens final surface on the optical axis, and Bf is the back focus (the lens front surface to the paraxial image surface on the optical axis). Distance).

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

  In [Values for Conditional Expressions] in the table, values corresponding to the conditional expressions (1) to (7) are shown.

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

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

(First embodiment)
A first embodiment will be described with reference to FIGS. As shown in FIG. 1, the zoom lens ZL (ZL1) according to the first example includes a first lens group G1 having a positive refractive power arranged in order from the object side along the optical axis, and a negative refractive power. A second lens group G2 having a negative refractive power, a third lens group G3 having a negative refractive power, and a fourth lens group G4 having a positive refractive power.

  The first lens group G1 is composed of a cemented positive lens formed by cementing a negative meniscus lens L11 having a convex surface toward the object side and a positive meniscus lens L12 having a convex surface toward the object side, which are arranged in order from the object side.

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

  The third lens group G3 includes a negative meniscus lens L31 having a concave surface directed toward the object side.

  The fourth lens group G4 includes a positive meniscus lens L41 arranged in order from the object side and having a convex surface directed toward the image side, and a cemented positive lens formed by cementing a biconvex positive lens L42 and a biconcave negative lens L43. An aperture stop S for determining the F number, a cemented negative lens formed by cementing a positive lens L44 having an aspheric surface on the object side and a negative lens L45 having a concave surface on the object side, and a convex surface facing the object side And a positive meniscus lens L46.

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

  The zoom lens ZL1 according to the first example includes an air gap between the first lens group G1 and the second lens group G2, an air gap between the second lens group G2 and the third lens group G3, and a third lens group G3. Is changed from the wide-angle end state to the telephoto end state. At this time, the first lens group G1 moves toward the object side with respect to the image plane I, the second lens group G2 moves along the optical axis so as to draw a convex locus on the image side, and the third lens. The group G3 moves to the image side, and the fourth lens group G4 moves to the object side. The aperture stop S moves to the object side together with the fourth lens group G4 during zooming.

  In addition, the third lens group G3 is configured to focus by moving along the optical axis direction, and as shown by the arrow in FIG. When the state is changed, the third lens group G3 moves from the image side to the object side.

  Further, when image blur occurs, the image blur correction on the image plane I is performed by moving the positive meniscus lens L41 of the fourth lens group G4 as a vibration-proof lens group so as to have a component perpendicular to the optical axis. Do.

  Table 1 below shows the values of each item in the first example. Surface numbers 1 to 22 in Table 1 correspond to the optical surfaces m1 to m22 shown in FIG.

(Table 1)
[Lens data]
Surface number R D nd νd
1 43.8295 1.2000 23.78 1.846660
2 31.7630 10.0000 52.34 1.755000
3 109.2239 D3 (variable)
4 50.1616 1.2000 31.31 1.903660
5 12.0806 6.8000
6 -100.4932 1.2000 46.51 1.804200
7 32.0847 0.5000
8 22.5028 4.0000 20.88 1.922860
9 10044.2545 D9 (variable)
10 -38.4460 1.0000 33.27 1.806100
11 -83.2624 D11 (variable)
12 -116.2034 1.0000 46.51 1.804200
13 -45.1463 1.2000
14 14.8637 4.0000 44.81 1.744000
15 -18.7249 1.0000 23.78 1.846660
16 228.6540 0.6500
17 ∞ 8.5459 (Aperture S)
* 18 248.5826 6.8772 63.30 1.514430
19 -7.7669 1.0000 46.51 1.804200
20 -1159.7397 0.1000
21 33.1411 3.0000 40.98 1.581440
22 3486.3112 Bf (variable)

[Aspherical data]
18th surface κ = 85.1749
A4 = -7.49845E-05
A6 = -1.69086E-08
A8 = -1.81387E-09
A10 = 7.35712E-11

[Each group interval data]
1-POS 2-POS 3-POS
f 18.40007 31.99983 52.00012
D0 0.0000 0.0000 0.0000
D3 0.79731 5.94803 26.60122
D9 4.43546 4.06170 5.95917
D11 15.72774 6.29491 2.04800
Bf 14.76613 24.10940 26.72106

4-POS 5-POS 6-POS
β -0.02509 -0.02525 -0.02376
D0 711.0157 1244.4755 2126.1737
D3 0.79731 5.94803 26.60122
D9 3.85803 3.67322 5.50483
D11 16.30517 6.68339 2.50233
Bf 15.01478 24.54574 27.38686

7-POS 8-POS 9-POS
β -0.05994 -0.10760 -0.16713
D0 284.6749 274.6815 248.6892
D3 0.79731 5.94803 26.60122
D9 3.05315 2.43554 2.94824
D11 17.11005 7.92106 5.05893
Bf 15.35663 25.95132 31.30984

[Various data]
f = 18.4 to 52.0
FNO = 3.66 to 6.00
ω = 40.37 to 15.08
Y = 14.25
TL = 89.000-114.603
Σd = 74.234 to 87.881
Bf = 14.766 to 26.721

[Lens group data]
Group number Group first surface Group focal length G1 1 97.17640
G2 4 -23.58581
G3 10 -89.49950
G4 12 19.53948

[Conditional expression values]
Conditional expression (1): f4 / fw = 1.062
Conditional expression (2): VRT = 0.596
Conditional expression (3): f1 / f4 = 4.973
Conditional expression (4): f2 / f3 = 0.264
Conditional expression (5): (−r) /fw=0.422
Conditional expression (6): ωw = 40.37
Conditional expression (7): ft / fw = 2.826

  From Table 1, it can be seen that the zoom lens ZL1 according to Example 1 satisfies all the conditional expressions (1) to (7).

FIGS. 2A and 2B are diagrams showing various aberrations (spherical aberration diagram, astigmatism diagram, distortion diagram, and chromatic aberration of magnification) when the zoom lens ZL1 according to the first example is in focus at infinity in the wide-angle end state. FIG. 10 is a coma aberration diagram when image blur correction (shift amount of image stabilizing group = 0.332) is performed. FIG. 3 is a diagram illustrating various aberrations when the zoom lens ZL1 according to Example 1 is in focus at infinity in the intermediate focal length state. 4A and 4B are graphs showing various aberrations (spherical aberration diagram, astigmatism diagram, distortion diagram, and chromatic aberration of magnification) when the zoom lens ZL1 according to the first example is in focus at infinity in the telephoto end state. FIG. 6 is a coma aberration diagram when image blur correction (shift amount of image stabilizing group = 0.457) is performed. In this embodiment, as shown in FIGS. 2 (b) and 4 (b), the optical performance at the time of image stabilization is a frame corresponding to an upper / lower plus / minus image height 10.0 with an image height y = 0.0 as the center. This is shown in the aberration diagram.

  In each aberration diagram, FNO is the F number, Y is the image height, d is the aberration at the d-line, and g is the aberration at the g-line. In the spherical aberration diagram, the F-number value corresponding to the maximum aperture is shown, and in the astigmatism diagram and the distortion diagram, the maximum image height is shown. In the astigmatism diagram, the solid line indicates the sagittal image plane, and the broken line indicates the meridional image plane. In the coma aberration diagram, the solid line indicates the meridional coma. The explanation of the above aberration diagrams is the same in the other examples, and the explanation is omitted.

  2A to 4B, the zoom lens ZL1 according to the first example has excellent correction with various aberrations including spherical aberration, curvature of field, astigmatism, coma, and the like. It can be seen that it has optical performance.

(Second embodiment)
A second embodiment will be described with reference to FIGS. As shown in FIG. 5, the zoom lens ZL (ZL2) according to the second example includes a first lens group G1 having a positive refractive power and a second lens having a negative refractive power, which are arranged in order from the object side. The lens group G2 includes a third lens group G3 having a negative refractive power, and a fourth lens group G4 having a positive refractive power.

  The first lens group G1 is composed of a cemented positive lens formed by cementing a negative meniscus lens L11 having a convex surface toward the object side and a positive meniscus lens L12 having a convex surface toward the object side, which are arranged in order from the object side.

  The second lens group G2 includes a negative meniscus lens L21 having a convex surface directed toward the object side, a negative meniscus lens L22 having a convex surface directed toward the object side, and a positive meniscus lens having a convex surface directed toward the object side. L23.

  The third lens group G3 includes a negative meniscus lens L31 having a concave surface directed toward the object side.

  The fourth lens group G4 is formed by joining a positive meniscus lens L41 having a convex surface toward the image side, a biconvex positive lens L42, and a negative meniscus lens L43 having a concave surface toward the object side, which are arranged in order from the object side. A cemented positive lens, an aperture stop S that determines the F number, a cemented negative lens formed by cementing a positive lens L44 having an aspheric surface on the object side, and a negative lens L45 having a concave surface on the object side, and biconvex And a positive lens L46 having a shape.

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

  The zoom lens ZL2 according to the second example includes an air gap between the first lens group G1 and the second lens group G2, an air gap between the second lens group G2 and the third lens group G3, and a third lens group G3. Is changed from the wide-angle end state to the telephoto end state. At this time, the first lens group G1 moves toward the object side with respect to the image plane I, the second lens group G2 moves along the optical axis so as to draw a convex locus on the image side, and the third lens. The group G3 moves to the image side, and the fourth lens group G4 moves to the object side. The aperture stop S moves to the object side together with the fourth lens group G4 during zooming.

  Further, the third lens group G3 is configured to focus by moving along the optical axis direction, and as shown by the arrows in FIG. When the state is changed, the third lens group G3 moves from the image side to the object side.

  Further, when image blur occurs, the image blur correction on the image plane I is performed by moving the positive meniscus lens L41 of the fourth lens group G4 as a vibration-proof lens group so as to have a component perpendicular to the optical axis. Do.

  Table 2 below shows the values of each item in the second embodiment. Surface numbers 1 to 22 in Table 2 correspond to the optical surfaces m1 to m22 shown in FIG.

(Table 2)
[Lens data]
Surface number R D nd νd
1 45.9725 1.2000 23.78 1.846660
2 32.4747 9.0000 52.34 1.755000
3 116.1757 D3 (variable)
4 30.2911 1.2000 31.31 1.903660
5 12.6889 8.0000
6 376.8193 1.2000 46.51 1.804200
7 17.0572 1.0000
8 17.4828 4.5000 20.88 1.922860
9 97.6208 D9 (variable)
10 -46.5874 1.0000 33.27 1.806100
11 -216.5990 D11 (variable)
12 -207.7276 1.0000 46.51 1.804200
13 -89.3144 1.2000
14 13.2573 3.5000 44.81 1.744000
15 -14.4070 0.8000 23.78 1.846660
16 -245.5609 2.0000
17 ∞ 5.7557 (Aperture S)
* 18 -72.5541 8.0000 63.88 1.516800
19 -8.6684 1.0000 46.59 1.816000
20 692.0816 0.1000
21 36.4834 2.8000 38.03 1.603420
22 -127.2725 Bf (variable)

[Aspherical data]
18th surface κ = 85.1749
A4 = -1.50694E-04
A6 = -1.49843E-06
A8 = -1.81387E-09
A10 = -4.41763E-10

[Each group interval data]
1-POS 2-POS 3-POS
f 18.40098 31.99898 52.00021
D0 0.0000 0.0000 0.0000
D3 0.79731 5.94803 26.60122
D9 4.43546 4.06170 5.95917
D11 15.72774 6.29491 2.04800
Bf 14.78536 23.94059 27.28426

4-POS 5-POS 6-POS
β -0.02498 -0.02517 -0.02368
D0 711.0157 1244.4755 2126.1737
D3 0.79731 5.94803 26.60122
D9 3.85803 3.67322 5.50483
D11 16.30517 6.68339 2.50233
Bf 15.00997 24.33266 27.85182

7-POS 8-POS 9-POS
β -0.05931 -0.10612 -0.16320
D0 284.6749 274.6815 248.6892
D3 0.79731 5.94803 26.60122
D9 3.05315 2.43554 2.94824
D11 17.11005 7.92106 5.05893
Bf 15.31172 25.56164 31.07180

[Various data]
f = 18.4 to 52.0
FNO = 3.64 to 5.90
ω = 38.66 to 15.00
Y = 14.25
TL = 89.002-115.148
Σd = 74.216 to 87.864
Bf = 14.785 to 27.284

[Lens group data]
Group number Group first surface Group focal length G1 1 102.79844
G2 4 -25.94477
G3 10 -73.82428
G4 12 19.16986

[Conditional expression values]
Conditional expression (1): f4 / fw = 1.042
Conditional expression (2): VRT = 0.275
Conditional expression (3): f1 / f4 = 5.362
Conditional expression (4): f2 / f3 = 0.351
Conditional expression (5): (−r) /fw=0.471
Conditional expression (6): ωw = 38.66
Conditional expression (7): ft / fw = 2.826

  From Table 2, it can be seen that the zoom lens ZL2 according to the second example satisfies all the conditional expressions (1) to (7).

FIGS. 6A and 6B are graphs showing various aberrations (spherical aberration diagram, astigmatism diagram, distortion diagram, and chromatic aberration of magnification) when the zoom lens ZL2 according to Example 2 is in focus at infinity in the wide-angle end state. FIG. 6 is a coma aberration diagram when image blur correction (shift amount of image stabilizing group = 0.733) is performed. FIG. 7 is a diagram illustrating various aberrations when the zoom lens ZL2 according to Example 2 is in focus at infinity in the intermediate focal length state. FIGS. 8A and 8B are graphs showing various aberrations (spherical aberration diagram, astigmatism diagram, distortion diagram, and chromatic aberration of magnification) at the time of focusing on infinity in the telephoto end state of the zoom lens ZL2 according to the second example. FIG. 9 is a coma aberration diagram when image blur correction (shift amount of image stabilizing group = 0.92) is performed. In this embodiment, as shown in FIGS. 6B and 8B, the optical performance at the time of image stabilization is a frame corresponding to an upper / lower plus / minus image height 10.0 centered on the image height y = 0.0. This is shown in the aberration diagram.

From the respective aberration diagrams shown in FIGS. 6 to 8, the zoom lens ZL2 according to Example 2 is excellent in correcting various aberrations including spherical aberration, curvature of field, astigmatism, coma and the like. It can be seen that it has optical performance.

(Third embodiment)
A third embodiment will be described with reference to FIGS. 9 to 12 and Table 3. FIG. As shown in FIG. 9, the zoom lens ZL (ZL3) according to the third example includes a first lens group G1 having a positive refractive power arranged in order from the object side, and a second lens group having a negative refractive power. The lens group G2 includes a third lens group G3 having a negative refractive power, and a fourth lens group G4 having a positive refractive power.

  The first lens group G1 is composed of a cemented positive lens formed by cementing a negative meniscus lens L11 having a convex surface toward the object side and a positive meniscus lens L12 having a convex surface toward the object side, which are arranged in order from the object side.

  The second lens group G2 includes a negative meniscus lens L21 having a convex surface directed toward the object side, a negative meniscus lens L22 having a convex surface directed toward the object side, and a positive meniscus lens having a convex surface directed toward the object side. L23.

  The third lens group G3 is composed of a biconcave negative lens L31.

  The fourth lens group G4 includes, in order from the object side, a biconvex positive lens L41, a cemented positive lens formed by cementing a biconvex positive lens L42 and a biconcave negative lens L43, and an F-number. A negative lens L44 having an aspheric surface on both sides, a positive meniscus lens L45 having a concave surface on the object side, and a negative lens L46 having a concave surface on the object side. And a biconvex positive lens L47.

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

  The zoom lens ZL3 according to Example 3 includes an air gap between the first lens group G1 and the second lens group G2, an air gap between the second lens group G2 and the third lens group G3, and a third lens group G3. Is changed from the wide-angle end state to the telephoto end state. At this time, the first lens group G1 moves to the object side, the second lens group G2 moves to the image side, the third lens group G3 moves to the image side, and the fourth lens group. G4 moves to the object side. The aperture stop S moves to the object side together with the fourth lens group G4 during zooming.

  Further, the third lens group G3 is configured to focus by moving along the optical axis direction, and as shown by the arrow in FIG. When the state is changed, the third lens group G3 moves from the image side to the object side.

  Further, when image blur occurs, the image blur correction on the image plane I is performed by moving the positive meniscus lens L41 of the fourth lens group G4 as a vibration-proof lens group so as to have a component perpendicular to the optical axis. Do.

  Table 3 below shows values of various specifications in the third example. Surface numbers 1 to 24 in Table 3 correspond to the optical surfaces m1 to m24 shown in FIG.

(Table 3)
[Lens data]
Surface number R D nd νd
1 38.2502 1.2000 23.78 1.846660
2 26.7321 9.0000 52.34 1.755000
3 70.8740 D3 (variable)
4 30.2911 1.0000 31.31 1.903660
5 12.6889 6.0000
6 35.9312 1.0000 46.51 1.804200
7 17.1890 1.0000
8 16.2094 4.0000 20.88 1.922860
9 59.1857 D9 (variable)
10 -45.6003 1.0000 33.27 1.806100
11 98.5667 D11 (variable)
12 53.9062 1.0000 46.51 1.804200
13 -107.1675 0.7000
14 9.1711 2.6000 52.34 1.755000
15 -24.2257 0.6000 23.78 1.846660
16 41.5680 1.0000
17 ∞ 1.8944 (Aperture S)
* 18 199.8522 1.0000 63.88 1.516800
* 19 -100.0000 1.0000
20 -27.5815 3.9125 58.82 1.518230
21 -3.8056 1.0000 46.59 1.816000
22 114.5395 0.1000
23 36.4834 2.3000 33.73 1.647690
24 -48.3556 Bf (variable)

[Aspherical data]
18th surface κ = 85.1749
A4 = 6.74722E-04
A6 = 2.72415E-05
A8 = -1.81387E-09
A10 = -2.78024E-07

Surface 19 κ = 1.0000
A4 = 4.93035E-04
A6 = 5.50621E-05
A8 = -3.63208E-06
A10 = -3.05333E-07

[Each group interval data]
1-POS 2-POS 3-POS
f 18.40085 31.99789 52.00054
D0 0.0000 0.0000 0.0000
D3 0.28473 5.43545 26.08863
D9 3.12280 2.74904 4.64651
D11 14.83468 5.40185 1.15494
Bf 10.46191 16.23636 18.16125

4-POS 5-POS 6-POS
β -0.02493 -0.02524 -0.02382
D0 711.0157 1244.4755 2126.1737
D3 0.28473 5.43545 26.08863
D9 2.54537 2.36056 4.19217
D11 15.41210 5.79032 1.60927
Bf 10.69526 16.64712 18.79284

7-POS 8-POS 9-POS
β -0.05904 -0.10716 -0.16767
D0 284.6749 274.6815 248.6892
D3 0.28473 5.43545 26.08863
D9 1.74049 1.12288 1.63558
D11 16.21699 7.02800 4.16587
Bf 10.99595 17.89061 22.15847

[Various data]
f = 18.4 to 52.0
FNO = 3.53 to 5.62
ω = 38.36 to 14.11
Y = 14.25
TL = 70.545 to 91.358
Σd = 59.549 to 73.197
Bf = 10.462 to 18.161

[Lens group data]
Group number Group first surface Group focal length G1 1 107.75402
G2 4 -60.57702
G3 10 -38.55679
G4 12 15.00386

[Conditional expression values]
Conditional expression (1): f4 / fw = 0.815
Conditional expression (2): VRT = 0.924
Conditional expression (3): f1 / f4 = 7.182
Conditional expression (4): f2 / f3 = 1.571
Conditional expression (5): (−r) /fw=0.207
Conditional expression (6): ωw = 38.36
Conditional expression (7): ft / fw = 2.826

  From Table 3, it can be seen that the zoom lens ZL3 according to Example 3 satisfies all the conditional expressions (1) to (7).

FIGS. 10A and 10B are diagrams showing various aberrations (spherical aberration diagram, astigmatism diagram, distortion diagram, and chromatic aberration of magnification) when the zoom lens ZL3 according to the third example is in focus at infinity in the wide-angle end state. FIG. 9 is a coma aberration diagram when performing image blur correction (shift amount of image stabilizing group = 0.216).
FIG. 11 is a diagram illustrating various aberrations when the zoom lens ZL3 according to Example 3 is in focus at infinity in the intermediate focal length state. 12A and 12B are graphs showing various aberrations (spherical aberration diagram, astigmatism diagram, distortion diagram, and chromatic aberration of magnification) when the zoom lens ZL3 according to the third example is in focus at infinity in the telephoto end state. FIG. 6 is a coma aberration diagram when image blur correction (shift amount of image stabilizing group = 0.295) is performed. In this example, the optical performance during image stabilization is shown in FIG. 10B and FIG.
As shown in (b), a coma aberration diagram corresponding to an upper / lower plus / minus image height 10.0 with the image height y = 0.0 as the center.

  10A to 12B, the zoom lens ZL3 according to the third example has excellent correction with various aberrations including spherical aberration, curvature of field, astigmatism, coma and the like. It can be seen that it has optical performance.

(Fourth embodiment)
A fourth embodiment will be described with reference to FIGS. 13 to 16 and Table 4. FIG. As shown in FIG. 13, the zoom lens ZL (ZL4) according to the fourth example includes a first lens group G1 having a positive refractive power and a second lens having a negative refractive power, which are arranged in order from the object side. The lens group G2 includes a third lens group G3 having a negative refractive power, and a fourth lens group G4 having a positive refractive power.

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

  The second lens group G2 includes a negative meniscus lens L21 having a convex surface facing the object side and an aspheric surface facing the object side, a negative meniscus lens L22 having a convex surface facing the image side, And a positive lens L23 having a shape.

  The third lens group G3 is composed of a biconcave negative lens L31.

  The fourth lens group G4 includes a positive meniscus lens L41 arranged in order from the object side and having a convex surface directed toward the object side, and a cemented positive lens formed by cementing a biconvex positive lens L42 and a biconcave negative lens L43. And an aperture stop S for determining the F number, a positive lens L44 having aspheric surfaces on both sides, a positive meniscus lens L45 having a concave surface on the object side, and a negative meniscus lens L46 having a concave surface on the object side. And a biconvex positive lens L47.

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

  The zoom lens ZL4 according to the fourth example includes an air space between the first lens group G1 and the second lens group G2, an air space between the second lens group G2 and the third lens group G3, and a third lens group G3. Is changed from the wide-angle end state to the telephoto end state. At this time, the first lens group G1 moves toward the object side with respect to the image plane I, the second lens group G2 moves along the optical axis so as to draw a convex locus on the image side, and the third lens. The group G3 moves along the optical axis so as to draw a convex locus on the image side, and the fourth lens group G4 moves to the object side. The aperture stop S moves to the object side together with the fourth lens group G4 during zooming.

  In addition, the third lens group G3 is configured to focus by moving along the optical axis direction, and as shown by the arrow in FIG. When the state is changed, the third lens group G3 moves from the image side to the object side.

  Further, when image blur occurs, the image blur correction on the image plane I is performed by moving the positive meniscus lens L41 of the fourth lens group G4 as a vibration-proof lens group so as to have a component perpendicular to the optical axis. Do.

  Table 4 below shows values of various specifications in the fourth embodiment. Surface numbers 1 to 24 in Table 4 correspond to the optical surfaces m1 to m24 shown in FIG.

(Table 4)
[Lens data]
Surface number R D nd νd
1 117.0356 1.2000 23.78 1.846660
2 55.9729 5.0000 52.34 1.755000
3 -643.8314 D3 (variable)
* 4 35.8382 1.0000 31.31 1.903660
5 14.3439 7.0000
6 -34.7156 1.0000 46.51 1.804200
7 -191.4209 0.1000
8 25.5833 3.8000 20.88 1.922860
9 -101.7184 D9 (variable)
10 -33.0329 1.0000 33.27 1.806100
11 76.6963 D11 (variable)
12 28.6596 1.0000 46.51 1.804200
13 321.1835 0.7000
14 11.0584 2.6000 52.34 1.755000
15 -30.7509 0.6000 23.78 1.846660
16 34.0209 1.0000
17 ∞ 4.3637 (Aperture S)
* 18 -213.7328 1.0000 63.88 1.516800
* 19 -32.7498 1.0000
20 -18.3365 4.0000 58.82 1.518230
21 -4.8697 1.0000 46.59 1.816000
22 -214.8274 0.1000
23 35.1245 2.0000 32.35 1.850 260
24 -88.3809 Bf (variable)

[Aspherical data]
4th surface κ = 0.8118
A4 = 3.23414E-06
A6 = -6.04464E-08
A8 = 3.00631E-10
A10 = -5.96901E-13

18th surface κ = 1.0000
A4 = 7.12812E-04
A6 = 1.59375E-05
A8 = -4.04113E-07
A10 = 4.21273E-08

Surface 19 κ = 1.0000
A4 = 8.03440E-04
A6 = 1.64331E-05
A8 = -4.58692E-07
A10 = 4.02611E-08

[Each group interval data]
1-POS 2-POS 3-POS
f 18.40048 31.98644 52.00321
D0 0.0000 0.0000 0.0000
D3 0.80071 5.95143 26.60461
D9 2.13426 1.76050 3.65797
D11 15.05176 5.61892 1.37201
Bf 12.55463 20.48689 26.87882

4-POS 5-POS 6-POS
β -0.02500 -0.02500 -0.02500
D0 698.7959 1233.7370 1987.5917
D3 0.80071 5.95143 26.60461
D9 1.23465 1.19556 3.12930
D11 15.95137 6.18386 1.90069
Bf 12.55463 20.48689 26.87882

7-POS 8-POS 9-POS
β -0.02758 -0.03290 -0.11767
D0 629.9950 926.7186 352.0229
D3 0.80071 5.95143 26.60461
D9 1.14204 1.01750 1.18983
D11 16.04397 6.36193 3.84015
Bf 12.55463 20.48689 26.87882

[Various data]
f = 18.4 to 52.0
FNO = 3.61 to 5.91
ω = 40.53 to 14.49
Y = 14.25
TL = 70.005 to 97.977
Σd = 57.450 to 71.098
Bf = 12.555 to 26.879

[Lens group data]
Group number Group first surface Group focal length G1 1 148.08761
G2 4 -494.72518
G3 10 -28.52640
G4 12 16.63602

[Conditional expression values]
Conditional expression (1): f4 / fw = 0.904
Conditional expression (2): VRT = 1.358
Conditional expression (3): f1 / f4 = 8.902
Conditional expression (4): f2 / f3 = 17.343
Conditional expression (5): (−r) /fw=0.265
Conditional expression (6): ωw = 40.53
Conditional expression (7): ft / fw = 2.826

  From Table 4, it can be seen that the zoom lens ZL4 according to Example 4 satisfies all the conditional expressions (1) to (7).

FIGS. 14A and 14B are graphs showing various aberrations (spherical aberration diagram, astigmatism diagram, distortion diagram, and chromatic aberration of magnification) at the time of focusing on infinity in the wide-angle end state of the zoom lens ZL4 according to the fourth example. FIG. 6 is a coma aberration diagram when image blur correction (shift amount of image stabilizing group = 0.168) is performed.
FIG. 15 is a diagram illustrating various aberrations when the zoom lens ZL2 according to Example 4 is in focus at infinity in the intermediate focal length state. FIGS. 16A and 16B are graphs showing various aberrations (spherical aberration diagram, astigmatism diagram, distortion aberration diagram, and chromatic aberration of magnification) when the zoom lens ZL4 according to Example 4 is in focus at infinity. FIG. 10 is a coma aberration diagram when image blur correction (shift amount of image stabilization group = 0.200) is performed. In this embodiment, as shown in FIGS. 14 (b) and 16 (b), the optical performance at the time of image stabilization is a frame corresponding to an upper / lower plus / minus image height 10.0 centering on the image height y = 0.0. This is shown in the aberration diagram.

  From the aberration diagrams shown in FIGS. 14 to 16, the zoom lens ZL4 according to Example 4 is excellent in correcting various aberrations including spherical aberration, curvature of field, astigmatism, coma and the like. It can be seen that it has optical performance.

  According to each of the embodiments described above, it is possible to realize a zoom lens having a wide angle of view, a small size, a short overall length, and excellent correction of spherical aberration, field curvature, astigmatism, coma, and the like.

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

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

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

  In this embodiment, the lens group or the partial lens group is vibrated in a direction perpendicular to the optical axis, or rotated (swinged) in an in-plane direction including the optical axis to correct image blur caused by camera shake. An anti-vibration lens group may be used. In particular, it is preferable that at least a part of the fourth lens group G4 is an anti-vibration lens group.

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

  In the present embodiment, the aperture stop S is preferably arranged in the vicinity of or in the fourth lens group G4. However, the role may be substituted by a lens frame without providing a member as the aperture stop.

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

  The zoom lens ZL of the present embodiment has a zoom ratio of about 2-7.

ZL (ZL1 to ZL4) Zoom lens G1 First lens group G2 Second lens group G3 Third lens group G4 Fourth lens group S Aperture stop I Image plane 1 Camera (imaging device)
2 Shooting lens (zoom lens)

Claims (12)

A first lens group having a positive refractive power, a second lens group having a negative refractive power, a third lens group having a negative refractive power, and a first lens group having a positive refractive power, arranged in order from the object side. It consists essentially of four lens groups with four lens groups,
Magnification is achieved by changing the air spacing between adjacent lens groups of the first to fourth lens groups,
A part of the fourth lens group is provided as a vibration-proof lens group for correcting image blur so as to be movable so as to have a component in a direction perpendicular to the optical axis,
A zoom lens satisfying the following conditional expression:
0.60 <f4 / fw <1.15
4.50 <f1 / f4 <11.00
However,
f1: the focal length of the first lens group,
f4: focal length of the fourth lens group,
fw: The focal length of the entire system in the wide-angle end state when focusing on infinity. A first lens group having a positive refractive power, a second lens group having a negative refractive power, a third lens group having a negative refractive power, and a first lens group having a positive refractive power, arranged in order from the object side. It consists essentially of four lens groups with four lens groups,
Magnification is achieved by changing the air spacing between adjacent lens groups of the first to fourth lens groups,
A part of the fourth lens group is provided as a vibration-proof lens group for correcting image blur so as to be movable so as to have a component in a direction perpendicular to the optical axis,
A zoom lens satisfying the following conditional expression:
0.60 <f4 / fw <1.15
0.596 ≤ VRT <2.00
4.00 <f1 / f4 <11.00
However,
f1: the focal length of the first lens group,
f4: focal length of the fourth lens group,
fw: focal length of the entire system in the wide-angle end state when focusing on infinity,
VRT: Anti-vibration coefficient in the telephoto end state of the anti-vibration lens group.
The anti-vibration coefficient VRT is defined by the following conditional expression.
VRT = | (1-Bvr) × Br |
However,
Bvr: lateral magnification of the anti-vibration lens group,
Br: lateral magnification of the entire optical system on the image side from the image stabilizing lens group. A first lens group having a positive refractive power, a second lens group having a negative refractive power, a third lens group having a negative refractive power, and a first lens group having a positive refractive power, arranged in order from the object side. It consists essentially of four lens groups with four lens groups,
Magnification is achieved by changing the air spacing between adjacent lens groups of the first to fourth lens groups,
A part of the fourth lens group is provided as a vibration-proof lens group for correcting image blur so as to be movable so as to have a component in a direction perpendicular to the optical axis,
A zoom lens satisfying the following conditional expression:
0.60 <f4 / fw <1.15
0.596 ≤ VRT ≤ 0.924
4.00 <f1 / f4 <11.00
However,
f1: the focal length of the first lens group,
f4: focal length of the fourth lens group,
fw: focal length of the entire system in the wide-angle end state when focusing on infinity,
VRT: Anti-vibration coefficient in the telephoto end state of the anti-vibration lens group.
The anti-vibration coefficient VRT is defined by the following conditional expression.
VRT = | (1-Bvr) × Br |
However,
Bvr: lateral magnification of the anti-vibration lens group,
Br: lateral magnification of the entire optical system on the image side from the image stabilizing lens group. A first lens group having a positive refractive power, a second lens group having a negative refractive power, a third lens group having a negative refractive power, and a first lens group having a positive refractive power, arranged in order from the object side. It consists essentially of four lens groups with four lens groups,
Magnification is achieved by changing the air spacing between adjacent lens groups of the first to fourth lens groups,
A part of the fourth lens group is provided as a vibration-proof lens group for correcting image blur so as to be movable so as to have a component in a direction perpendicular to the optical axis,
The fourth lens group has one positive lens closest to the image side, and a cemented negative lens formed by cementing a positive lens and a negative lens with a convex cemented surface facing the image side facing the object side Have
A zoom lens satisfying the following conditional expression:
0.60 <f4 / fw <1.15
0.10 <VRT ≦ 0.596
However,
f4: focal length of the fourth lens group,
fw: focal length of the entire system in the wide-angle end state when focusing on infinity,
VRT: Anti-vibration coefficient in the telephoto end state of the anti-vibration lens group.
The anti-vibration coefficient VRT is defined by the following conditional expression.
VRT = | (1-Bvr) × Br |
However,
Bvr: lateral magnification of the anti-vibration lens group,
Br: lateral magnification of the entire optical system on the image side from the image stabilizing lens group. The zoom lens according to claim 1, wherein the following conditional expression is satisfied.
0.10 <VRT <2.00
However,
VRT: Anti-vibration coefficient in the telephoto end state of the anti-vibration lens group.
The anti-vibration coefficient VRT is defined by the following conditional expression.
VRT = | (1-Bvr) × Br |
However,
Bvr: lateral magnification of the anti-vibration lens group,
Br: lateral magnification of the entire optical system on the image side from the image stabilizing lens group. The zoom lens according to claim 4, wherein the following conditional expression is satisfied.
3.00 <f1 / f4 <11.00
However,
f1: Focal length of the first lens group. The fourth lens group has one positive lens closest to the image side, and a cemented negative lens formed by cementing a positive lens and a negative lens with a convex cemented surface facing the image side facing the object side The zoom lens according to claim 1, further comprising: The zoom lens according to claim 1, wherein the following conditional expression is satisfied.
0.10 <f2 / f3 <20.00
However,
f2: focal length of the second lens group,
f3: focal length of the third lens group. The zoom lens according to claim 4, wherein the following conditional expression is satisfied.
0.10 <(-r) / fw <2.00
However,
r: radius of curvature of the cemented surface of the cemented negative lens in the fourth lens group. The zoom lens according to claim 1, wherein the following conditional expression is satisfied.
30.00 ° <ωw <80.00 °
However,
ωw: Half angle of view in the wide-angle end state. The zoom lens according to claim 1, wherein the following conditional expression is satisfied.
2.00 <ft / fw <15.00
However,
ft: The focal length of the entire system in the telephoto end state when focusing on infinity.   An imaging apparatus comprising the zoom lens according to claim 1.

Images