JP4794845B2 - Zoom lens and imaging apparatus having the same - Google Patents

Description

  The present invention relates to a zoom lens and an image pickup apparatus having the same, and is suitable for an image pickup apparatus such as a video camera or a digital still camera.

  Recently, many imaging devices (cameras) such as video cameras and digital still cameras use a solid-state imaging device having a large number of pixels (high pixels), and a high-performance zoom lens is required for an optical system used therefor. .

  In particular, zoom lenses for high-pixel imaging devices are required to sufficiently correct chromatic aberration not only for chromatic aberration but also for a wide wavelength range. In general, in a zoom lens having a high zoom ratio (high zoom ratio), if the focal length of the entire system is long at the telephoto end, reduction of the secondary spectrum is strongly required for chromatic aberration in addition to primary achromaticity.

  Conventionally, many zoom lenses using a lens made of glass having anomalous dispersion for correcting the secondary spectrum of longitudinal chromatic aberration at the telephoto end are known. As a zoom configuration of a zoom lens suitable for increasing the zoom ratio, a positive lead type zoom lens in which the most object side lens unit is a lens unit having a positive refractive power can be cited.

  In order from the object side, zoom lenses using lenses made of glass having anomalous dispersion in a three-group zoom lens composed of positive, negative, and positive refractive power lens groups are known (for example, Patent Documents 1 to 3). 3).

  A zoom lens using a lens made of glass having anomalous dispersion in a four-group zoom lens composed of lens groups having positive, negative, positive and positive refractive powers in order from the object side is known (for example, patents). References 4-8).

Further, in order from the object side, a zoom lens using a lens made of glass having anomalous dispersion in a five-group zoom lens composed of lens groups of positive, negative, positive, negative, and positive refractive power is known ( For example, Patent Documents 9 to 12).
Patent No. 3008580 JP-A-6-43363 Japanese Patent Publication No. 3-58490 Patent No. 3097399 Japanese Patent Laid-Open No. 2002-62478 JP 2000-32499 A JP-A-8-248317 JP 2001-194590 A Japanese Patent Laid-Open No. 9-5624 Japanese Patent Laid-Open No. 2002-62478 JP 2001-350093 A JP 2001-194590 A

  In a positive lead type zoom lens with a high zoom ratio, the secondary spectrum of axial chromatic aberration tends to be large in the zoom region on the telephoto side. In order to reduce the secondary spectrum of axial chromatic aberration, it is effective to use an anomalous dispersion material having a low dispersion and a small partial dispersion ratio.

  In Patent Documents 2, 5, 7, 8, and 11, glass having anomalous dispersion with an Abbe number exceeding 80 is used as the material of the positive lens in the first lens unit having a positive refractive power.

  In general, a low dispersion glass having an Abbe number exceeding 80 has anomalous dispersion, and when used for a positive lens in the first lens group of positive lead, there is an effect of reducing the secondary spectrum on the telephoto side. However, anomalous dispersive materials are generally difficult to process and particularly difficult to manufacture when used for the first lens group having a large diameter.

  In Patent Documents 1 to 5 and 9, the secondary spectrum is reduced by using a glass having an anomalous dispersion with an Abbe number exceeding 80 as the material of the positive lens in the third lens group having a positive refractive power.

  However, the negative lens material in the third lens group has not been disclosed as having anomalous dispersion characteristics, and as a method for reducing the secondary spectrum, the use of anomalous dispersion characteristic glass as the positive lens material is disclosed. It was only there. For this reason, in order to reduce the amount of secondary spectrum in order to increase the number of pixels of the image sensor, it has been necessary to use a material having a higher anomalous dispersion such as fluorite for the positive lens in the third lens group. .

  The present invention is a zoom lens capable of satisfactorily correcting chromatic aberration, particularly the secondary spectrum, and obtaining high optical performance in the entire zoom range from the wide-angle end to the telephoto end by appropriately using a lens made of an anomalous dispersion material. The purpose is to provide.

The zoom lens according to the present invention includes, in order from the object side to the image side, a first lens group having a positive refractive power, a second lens group having a negative refractive power, a third lens group having a positive refractive power, and a positive refractive power. is a fourth lens unit, at the telephoto end than at the wide-angle end, the distance between the first lens and the second lens group and group is wide, it narrows the distance between the second lens and the third lens group and group Ri, wherein the third lens group and the distance between the fourth lens group changing the interval each lens group so that widens zoom lens for zooming, the third lens group, Nyudi3n the Abbe number, a partial dispersion When the ratio is θgF3n,
10 <νd3n ≦ 28.3
−0.0027νd3n + 0.620 <θgF3n <−0.0027νd3n + 0.680
It is characterized by having a negative lens made of a material that satisfies the following conditions.
In addition, the zoom lens according to the present invention includes, in order from the object side to the image side, a first lens group having a positive refractive power, a second lens group having a negative refractive power, a third lens group having a positive refractive power , and a negative refraction. the fourth lens group of the force, is composed of a fifth lens unit having positive refractive power, at the telephoto end than at the wide-angle end, the spacing of the first lens group and the second lens group becomes large, the second lens Ri a narrow interval between the the group third lens group, the distance between the fourth lens group and the third lens group becomes large, so that the distance of said fifth lens group and the fourth lens group is narrowed each by changing the distance between the lens units in the zoom lens for zooming, the third lens group, Nyudi3n an Abbe number, when the partial dispersion ratio and ShitagF3n,
10 <νd3n ≦ 28.3
−0.0027νd3n + 0.620 <θgF3n <−0.0027νd3n + 0.680
It is characterized by having a negative lens made of a material that satisfies the following conditions.

  According to the present invention, it is possible to realize a zoom lens that can satisfactorily correct chromatic aberration and obtain high optical performance in a wide zoom range.

  Embodiments of the zoom lens of the present invention and an image pickup apparatus having the same will be described below.

  FIG. 1 is an explanatory diagram of the paraxial refractive power arrangement of the zoom lenses of Examples 1 to 6 as an example of the zoom lens of the present invention.

  FIG. 2 is a cross-sectional view of a main part of the zoom lens of Example 1, and FIGS. 3 to 5 are aberration diagrams of the zoom lens of Example 1 at the wide-angle end, the intermediate focal length, and the telephoto end.

  FIG. 6 is a cross-sectional view of a main part of the zoom lens of Example 2, and FIGS. 7 to 9 are aberration diagrams of the zoom lens of Example 2 at the wide angle end, the intermediate focal length, and the telephoto end.

FIG. 10 is a cross-sectional view of the main part of the zoom lens of Reference Example 1 , and FIGS. 11 to 13 are aberration diagrams of the zoom lens of Reference Example 1 at the wide angle end, intermediate focal length, and telephoto end.

FIG. 14 is a cross-sectional view of a main part of the zoom lens of Example 3 , and FIGS. 15 to 17 are aberration diagrams of the zoom lens of Example 3 at the wide angle end, the intermediate focal length, and the telephoto end.

FIG. 18 is a cross-sectional view of a principal part of the zoom lens of Example 4 , and FIGS. 19 to 21 are aberration diagrams of the zoom lens of Example 4 at the wide angle end, the intermediate focal length, and the telephoto end.

FIG. 22 is a cross-sectional view of a principal part of the zoom lens of Example 5 , and FIGS. 23 to 25 are aberration diagrams of the zoom lens of Example 5 at the wide angle end, the intermediate focal length, and the telephoto end.

FIG. 26 is a cross-sectional view of a principal part of the zoom lens of Example 6 , and FIGS. 27 to 29 are aberration diagrams of the zoom lens of Example 6 at the wide-angle end, the intermediate focal length, and the telephoto end.

  FIG. 30 is an explanatory diagram showing the relationship between the Abbe number νd and the partial dispersion ratio Θg, F, and FIGS. 31 and 32 are schematic diagrams of image pickup apparatuses according to Examples 8 and 9 of the present invention.

In the lens sectional views of the zoom lenses of Examples 1 and 2, Reference Example 1, and Examples 3 to 5 shown in FIGS. 2, 6, 10, 14, 18, and 22, L1 is a positive refractive power. L2 is a second lens group having a negative refractive power, L3 is a third lens group having a positive refractive power, and L4 is a fourth lens group having a positive refractive power. SP is an aperture stop, which is located in front of the third lens unit L3.

In the lens cross-sectional view of the zoom lens of Example 6 shown in FIG. 26, L1 is a first lens unit having a positive refractive power, L2 is a second lens unit having a negative refractive power, and L3 is a third lens unit having a positive refractive power. A lens group, L4 is a fourth lens group having a negative refractive power, and L5 is a fifth lens group having a positive refractive power. After all, SP is an aperture stop and is located in front of the third lens unit L3.

  In the lens cross-sectional views of FIGS. 2, 6, 10, 14, 18, 22, and 26, G corresponds to an optical filter, a face plate, a color separation prism, etc., and is an optical block provided by design. is there. IP is an image plane on which an imaging plane of a solid-state imaging device (photoelectric conversion device) such as a CCD sensor or a CMOS sensor is located. In the lens cross-sectional view, the left side is the object side and the right side is the image side.

  In the aberration diagrams, d, g, C and F are d-line, g-line, C-line and F-line, ΔM and ΔS are meridional image surface and sagittal image surface, and lateral chromatic aberration is expressed by g-line, C-line and F-line. Yes.

In each example and reference example , each lens group is moved as indicated by an arrow during zooming from the wide-angle end to the telephoto end.

  Note that the wide-angle end and the telephoto end are zoom positions when the zooming lens groups are positioned at both ends of a range in which the lens group can be moved in the optical axis direction.

In each example and reference example , during zooming from the wide-angle end to the telephoto end, the first lens unit L1 is moved to the object side and the second lens unit L2 is set so that the distance between the first lens unit L1 and the second lens unit L2 is widened. The second lens unit L2 is moved to the image side so that the distance between the aperture SP and the stop SP is narrowed, and the third lens unit L3 is moved to the object side so that the distance between the second lens unit L2 and the third lens unit L3 is narrowed. Image plane fluctuations associated with zooming are corrected by moving the fourth lens unit L4 (in the sixth embodiment, the fifth lens unit L5).

  By moving the first lens unit L1 during zooming, the total lens length at the wide-angle end is shortened, and the entire lens system in the optical axis direction is downsized. In addition, the effective diameter of the first lens unit L1 is reduced by reducing the distance between the first lens unit L1 and the stop SP on the wide-angle side compared to the telephoto side, thereby reducing the size of the front lens.

  The third lens unit L3 is moved toward the object side during zooming from the wide-angle end to the telephoto end, and is moved so that the distance between the third lens unit L3 and the fourth lens unit L4 is widened. The group L3 is assigned the zooming action. Accordingly, it is possible to weaken the zooming effect due to the change in the distance between the first lens group L1 and the second lens group L2, and it is possible to shorten the distance between the first lens group L1 and the second lens group L2 at the telephoto end. As a result, the total lens length on the telephoto side is shortened and the front lens diameter is reduced.

The aperture stop SP may be moved integrally with the third lens unit L3 during zooming or may be moved separately. When integrated, the number of movements is reduced and the mechanical structure is easily simplified. Further, when the lens is moved separately from the third lens unit L3, the front lens diameter can be easily reduced particularly by moving the third lens unit L3 along a convex locus on the object side. Next, features of each embodiment and reference example will be described.

The zoom lens of each embodiment includes, in order from the object side to the image side, a first lens unit L1 having a positive refractive power, a second lens unit L2 having a negative refractive power, a third lens unit L3 having a positive refractive power, This has a rear group including one or more lens groups, and the distance between the first lens group L1 and the second lens group L2 at the telephoto end is wider than the wide-angle end, and the second lens group L2 and the third lens group Zooming is performed by moving the lens groups so that the distance between the lens groups L3 is narrow. Examples 1 and 2, Reference Example 1 and Examples 3 to 5 are examples in which the rear group is configured only by the fourth lens group having a positive refractive power. In Example 6 , the rear group is In this example, the fourth lens unit has a negative refractive power and the fifth lens unit has a positive refractive power.

  In each embodiment, one or more of the following conditional expressions are satisfied, thereby obtaining an effect corresponding to each conditional expression.

The third lens unit L3 has one or more negative lenses, and the refractive index and Abbe number of the material of the predetermined negative lens A in the third lens unit L3 are N3n and νd3n, the partial dispersion ratios are Θg, F3n, The focal length of the negative lens A is f3n, the focal lengths of the first, second, and third lens groups are f1, f2, and f3, respectively. The focal length at the telephoto end in the entire system is ft, and the Abbe number of the third lens group L3 is The Abbe number of the largest positive lens B is νd3p, the partial dispersion ratio of the positive lens B is Θg, F3p, the negative lens A is the radius of curvature of the concave surface in contact with air R3n, and the focal length of the cemented lens including the negative lens A is f3s. When the Abbe number of the material of the positive lens constituting the cemented lens is νd3ps and the partial dispersion ratio is Θg, F3ps, 10 <νd3n ≦ 28.3 (1)
−0.0027νd3n + 0.620 <Θg, F3n <−0.0027νd3n + 0.680 (2)
0.2 <| f3n | / f3 <3.5 (3)
0.2 <f3 / ft <0.8 (4)
−0.0030 <(Θg, F3n−Θg, F3p) / (νd3n−νd3p) (5)
1.80 <N3n (6)
0.2 <| R3n | / f3 <1.2 (7)
0.01 <| f3n | / f3s <1.5 (8)
−0.0030 <(Θg, F3n−Θg, F3ps) / (νd3n−νd3ps) (9)
0.5 <f1 / ft <2.2 (10)
0.1 <| f2 | / ft <0.4 (11)
Is satisfied.

  Here, when the refractive indices of materials in the d-line, F-line, C-line, and g-line of the Fraunhofer line are Nd, NF, NC, and Ng in this order, the Abbe number νd of the material and the partial dispersion ratios Θg and F are

It is.

  Next, the technical meaning of each conditional expression described above will be described.

  Conditional expression (1) defines the Abbe number νd3n of the negative lens A of the third lens unit L3. When the Abbe number increases beyond the upper limit, the dispersion becomes too small and the positive lens of the third lens unit L3. The generated primary chromatic aberration is insufficiently corrected.

  Further, when the Abbe number decreases beyond the lower limit, the dispersion increases and the refractive power of the negative lens A for correcting primary chromatic aberration decreases. If the refractive power of the negative lens A is too weak, the effect of correcting the Petzval sum to the minus side is weakened and the image surface curvature occurs on the under side, which is not good.

  Conditional expression (2) defines the partial dispersion ratio Θg, F3n of the negative lens A of the third lens unit L3. In FIG. 30, Θg, F3n = −0.0027νd3n + 0.680 is the line segment E, which means that the conditional expression (2) is located below the line segment E in FIG. The line segment E is a line segment having the same inclination as that of the reference line 2, and the glass satisfying the conditional expression (2) is a material having a small partial dispersion ratio for the glass in the vicinity of the reference line 2 instead of high dispersion.

  A material that exceeds the upper limit of conditional expression (2) and is above the line segment E in FIG. 30 has a high partial dispersion ratio as a high dispersion material, and when used for the negative lens A, the effect of correcting the secondary spectrum. And the secondary spectrum is undercorrected. Further, in FIG. 30, Θg, F3n = −0.0027νd3n + 0.620 is the line segment F, which means that the conditional expression (2) is located above the line segment F in FIG.

  In the material below the line segment F in FIG. 30 exceeding the lower limit of the conditional expression (2), the correction capability of the secondary spectrum is increased, but the correction capability is too high and the refractive power of the negative lens A is weakened. If the refractive power of the negative lens A is too weak, the effect of correcting the Petzval sum to the minus side is weakened and the image surface curvature occurs on the under side, which is not good.

  Conditional expression (3) defines the focal length of the negative lens A of the third lens unit L3. If the upper limit is exceeded and the focal length of the negative lens A is too long, that is, if the refractive power of the negative lens A is too weak, even if high dispersion glass is used, the primary chromatic aberration in the third lens unit L3 is insufficiently corrected.

  Also, the effect of correcting the secondary spectrum is diminished. If the lower limit is exceeded and the focal length of the negative lens A is too short, that is, if the refractive power of the negative lens A is too strong, the Petzval sum will increase on the negative side and an image surface curvature will occur on the over side.

  Conditional expression (4) defines the focal length of the third lens unit L3. If the upper limit is exceeded and the focal length of the third lens unit L3 is too long, the distance from the third lens unit L3 to the focus surface becomes longer, and the overall length increases.

  If the lower limit is exceeded and the focal length of the third lens unit L3 becomes too short, that is, if the refractive power is too strong, spherical aberration will occur in the third lens unit L3 and correction will be difficult even if an aspherical surface is used. .

  Conditional expression (5) is an expression defining the relationship between the partial dispersion ratios of the negative lens A and the positive lens in the third lens unit L3. In Conditional Expression (5), (Θg, F3n−Θg, F3p) / (νd3n−νd3p) connects the corresponding points from the Abbe numbers and partial dispersion ratios of the negative lens A and the positive lens in the third lens unit L3 in FIG. This represents the slope of the ellipse line. The smaller the slope, the easier the secondary spectrum is reduced.

  If the inclination becomes too large beyond the lower limit, it is difficult to reduce the secondary spectrum even if glass satisfying conditional expressions (1) and (2) is used for the negative lens. In each embodiment, it is particularly preferable that the negative lens A satisfies the conditional expressions (1) and (2) and the positive lens of the third lens unit L3 satisfies the conditional expression (5).

  Conditional expression (6) defines the refractive index of the material of the negative lens A of the third lens group. When the refractive power of the material of the negative lens A of the third lens unit L3 satisfies the conditional expression (3), if the refractive index becomes too small exceeding the lower limit of the conditional expression (6), the Petzval sum increases to the negative side. It is not good because a field curvature occurs on the over-over side.

  Conditional expression (7) defines the radius of curvature of the concave surface of the negative lens A. If the curvature exceeds the upper limit and the curvature is too loose, the effect of correcting the secondary spectrum is diminished. If the curvature exceeds the lower limit and the curvature is too tight, spherical aberration and coma will occur significantly, and correction will be difficult even if an aspherical surface is used.

  Conditional expression (8) defines the focal length of the negative lens A constituting the cemented lens in the third lens unit L3. When the focal length of the negative lens A is too long with respect to the focal length of the cemented lens beyond the upper limit, that is, when the refractive power is too weak, the effect of correcting the secondary spectrum by the negative lens A is diminished.

  Further, when the focal length is too short beyond the lower limit, that is, when the refractive power is too strong, aberrations generated on the cemented surface, for example, higher-order chromatic aberration, spherical aberration, coma aberration, etc. increase, which is not good.

  Conditional expression (9) defines the relationship between the partial dispersion ratios of the negative lens A and the positive lens constituting the cemented lens in the third lens unit L3, and the secondary spectrum is corrected well by the cemented lens. It is a condition for. (Θg, F3n−Θg, F3ps) / (νd3n−νd3ps) in the conditional expression (9) connects the corresponding points from the Abbe numbers and partial dispersion ratios of the negative lens A and the positive lens constituting the cemented lens in FIG. This represents the slope of the line segment. The smaller the slope, the lower the secondary spectrum. If the slope becomes too large beyond the lower limit, correction of the secondary spectrum becomes difficult even if glass satisfying conditional expressions (1) and (2) is used for the negative lens A.

  In each embodiment, it is preferable that the positive lens constituting the cemented lens satisfies the conditional expression (9) after the negative lens A satisfies the conditional expressions (1) and (2).

  Conditional expression (10) defines the focal length of the first lens unit L1. If the focal length of the first lens unit L1 is too long beyond the upper limit, that is, if the refractive power of the first lens unit L1 is too weak, the total length at the telephoto end becomes long. If the lower limit is exceeded and the focal length of the first lens unit L1 becomes too short, that is, if the refractive power of the first lens unit L1 is too strong, the occurrence of spherical aberration at the telephoto end becomes significant.

  Conditional expression (11) defines the focal length of the second lens unit L2. If the focal length of the second lens unit L2 becomes too long beyond the upper limit, that is, if the refractive power of the second lens unit L2 is too weak, the second lens unit L2 moves to ensure a desired zoom ratio during zooming. Since the amount increases, the overall length at the wide-angle end increases.

  If the lower limit value is exceeded and the focal length of the second lens unit L2 becomes too short, that is, if the refractive power of the second lens unit L2 is too strong, the Petzval sum increases on the negative side and the occurrence of field curvature increases. Not good.

  More preferably, the numerical ranges of the conditional expressions (1) to (11) are set as follows.

15 <νd3n ≦ 28.3 (1a)
−0.0027νd3n + 0.650 <Θg, F3n <−0.0027νd3n + 0.676 (2a)
0.3 <| f3n | / f3 <3.2 (3a)
0.3 <f3 / ft <0.7 (4a)
−0.0025 <(Θg, F3n−Θg, F3p) / (νd3n−νd3p) (5a)
1.85 <N3n (6a)
0.3 <| R3n | / f3 <1.1 (7a)
0.02 <| f3n | / f3s <1.45 (8a)
−0.0025 <(Θg, F3n−Θg, F3ps) / (νd3n−νd3ps) (9a)
0.6 <f1 / ft <2.1 (10a)
0.12 <| f2 | / ft <0.35 (11a)
Conditional expression (2a) limits conditional expression (2) to both an upper limit value and a lower limit value. If conditional expression (2a) is satisfied, secondary spectrum correction and field curvature correction are more compatible. is there.

  Conditional expression (6a) is limited to the higher refractive index side than conditional expression (6), and it becomes easier to obtain a flat image surface characteristic by further reducing image surface curvature.

  Next, specific features of each embodiment will be described.

  In Example 1 of FIG. 2, during zooming from the wide-angle end to the telephoto end, the first lens unit L1 is on the object side, the second lens unit L2 is a convex locus on the image side, and the third lens unit L3 is on the object side. The fourth lens unit L4 moves along a locus convex toward the object side.

  The first lens unit L1 is composed of a cemented lens composed of a negative lens and a positive lens in order from the object side, and a positive lens, and each color correction of axial chromatic aberration and chromatic aberration of magnification and correction of spherical aberration are performed with a high zoom ratio. I am doing.

  The second lens unit L2 is composed of four lenses in order from the object side to the image side: a negative lens having a negative image side, a negative lens having a meniscus shape, a positive lens having both lens surfaces having a convex shape, and a negative lens. is doing.

  The configuration of the third lens unit L3 is composed of a positive lens 31 and a negative lens 32 in order from the object side to the image side, and is composed of a cemented lens 36 having a positive refractive power as a whole, and a negative lens 33 and a positive lens 34 as a whole. It is composed of five elements in three groups, a cemented lens 37 having a refractive power and a positive lens 35. Here, the negative lens 33 is the above-described negative lens A, and the secondary spectrum of axial chromatic aberration is reduced by using a material having a relatively small partial dispersion ratio as the high dispersion glass material.

  The material of the negative lens 33 is trade name S-LAH79 (Nd = 2.00330, νd = 28.3, Θg, F = 0.598) manufactured by OHARA INC.

  FIG. 30 is a graph showing the relationship between the Abbe number νd of the optical material and the partial dispersion ratio Θg, F. In the figure, point A is a trade name PBM2 (νd = 36.26, Θg, F = 0.5828) manufactured by OHARA INC., And point B is a trade name NSL7 (νd = 60.49, Θg, F = 0.5436) manufactured by OHARA INC. ), Point C is a trade name S-TIH53 (νd = 23.8, Θg, F = 0.621) manufactured by OHARA, Inc., and point D is a trade name S-TIM22 (νd = 33.8, Θg, manufactured by OHARA CORPORATION. , F = 0.594).

  Assuming that the line connecting points A and B is the reference line 1, as a distribution of the optical glass, a high dispersion glass having an Abbe number νd smaller than about 35 is roughly above the reference line 1 and an Abbe number νd is 35. Many low-dispersion glasses up to about 65 are located below the reference line 1, and there exists an anomalous dispersion glass located above the reference line 1 when νd is 60 or more.

  However, in the high dispersion glass whose Abbe number νd is smaller than 35, there are not many that are located below the reference line 1 connecting the points A and B, so the points C and D are connected to the high dispersion glass. The line is defined as reference line 2 in the high dispersion glass. At this time, when the Abbe number νd is 35 or less, a lot of glass located near the reference line 2 is seen, but some of them are located below the reference line 2. As an example, the trade name S-LAH79 is located below the reference line 2 and is characterized by a relatively small partial dispersion ratio as a high dispersion material.

  When such a material is used for the negative lens of the third lens unit L3, there is an effect that the secondary spectrum of axial chromatic aberration can be reduced.

  In the lens configuration of the third lens unit L3 of Example 1 shown in FIG. 2, a negative lens using glass having a small partial dispersion ratio as a high dispersion material has a certain refractive power, and a positive lens in the third lens unit L3 is used. As low dispersion, the secondary spectrum is reduced without using anomalous dispersion glass having a large partial dispersion ratio.

  The third lens unit L3 has a high axial ray height in the entire zoom range from zooming to the telephoto end, and has a secondary spectrum correction effect in the entire zoom range with respect to axial chromatic aberration. is doing.

  Further, as the positive lens material of the third lens unit L3, a glass having anomalous dispersion characteristics with a large partial dispersion ratio (a glass positioned above the reference line 1 with an Abbe number νd of 60 or more in FIG. 30) is used. It is good to use, and according to this, a further secondary spectrum can be reduced. As described above, the negative lens material has a relatively small partial dispersion ratio for high dispersion, and the positive lens material has a relatively large partial dispersion ratio for low dispersion. Therefore, it is easy to cope with a high-pixel image sensor, to increase the zoom ratio by increasing the focal length at the telephoto end.

Next, Example 2 in FIG. 6 will be described. The basic lens configuration, such as the refractive power of each lens group and the movement conditions of each lens group during zooming, is the same as that of the first embodiment shown in FIG.

  The negative lens 23 of the third lens unit L3 is trade name S-LAH79 (νd = 28.3, Θg, F = 0.598) manufactured by OHARA INC., And the positive lens 24 is trade name S manufactured by OHARA INC. -FPL51 (νd = 81.5, Θg, F = 0.538) is used. The negative lens 23 is made of a material having a relatively small partial dispersion ratio for high dispersion, and the positive lens 24 is made of a material having a relatively large partial dispersion ratio for low dispersion, thereby favorably correcting the secondary spectrum. ing. In particular, by using a cemented lens, the secondary spectrum is easily corrected without causing extremely high-order aberrations.

  Next, Reference Example 1 in FIG. 10 will be described. The basic lens configuration is the same as in Example 1. The negative lens 32 of the third lens unit L3 is a negative lens having a concave surface on the image side. The material used is NBFD15 (νd = 33.3, Θg, F = 0.588) manufactured by HOYA Corporation. ing. The material of the positive lenses 34 and 35 is trade name S-FPL manufactured by OHARA INC. The negative lens 32 is a material having a relatively small partial dispersion ratio as high dispersion, but the refractive power is enhanced by increasing the curvature of the lens surface on the image side in contact with air to a certain degree, thereby enhancing the effect of correcting the secondary spectrum.

  The positive lenses 34 and 35 are made of a material having a relatively large partial dispersion ratio as low dispersion, and the secondary spectrum is corrected well in addition to the effects obtained when the negative lens 32 is used.

Next, Example 3 in FIG. 14 will be described. The basic lens configuration is the same as in Example 1.

The third embodiment is different from the first embodiment in that the third lens unit L3 has a three-group four-lens configuration. The negative lens 42 of the third lens unit L3 is a negative lens having a concave surface on the image side, and the material name is S-LAH79 (νd = 28.3, Θg, F = 0.598) manufactured by OHARA INC. Is used. The positive lens 43 is made of a material of trade name S-FPL51 (νd = 81.5, Θg, F = 0.538) manufactured by OHARA INC. The negative lens 42 is made of a material having a relatively small partial dispersion ratio for high dispersion, and the curvature of the lens surface on the image side in contact with the air is tightened to some extent to increase the refractive power and enhance the secondary spectrum correction effect. .

In addition to the effect of using the negative lens 42 by using a material having a relatively large partial dispersion ratio as the low dispersion for the positive lens 43, the secondary spectrum is corrected well.

Next, Example 4 in FIG. 18 will be described. The basic lens configuration is the same as in Example 1. Tellurite glass (νd = 17.6, Θg, F = 0.626) is used for the negative lens 53 of the third lens unit L3. As the material of the positive lens 54, trade name S-FPL51 (νd = 81.6, Θg, F = 0.538) manufactured by OHARA INC. Is used. The negative lens 53 uses a material with a relatively small partial dispersion ratio for high dispersion, and the positive lens 54 uses a material with a relatively large partial dispersion ratio for low dispersion, thereby enhancing the correction effect of the secondary spectrum. . In particular, by using a cemented lens, the secondary spectrum is satisfactorily corrected without causing extremely high-order aberrations.

Next, Example 5 of FIG. 22 will be described. The fifth embodiment is a zoom lens including four lens groups, and the refractive power arrangement of each lens group is the same as that of the first embodiment. The fifth embodiment is the same as the first embodiment in that all lens units move during zooming, but the second lens unit L2 monotonously moves to the image side during zooming from the wide-angle end to the telephoto end. The third lens unit L3 and the fourth lens unit L4 are both moved along a locus convex toward the object side.

  The second lens unit L2 is composed of three lenses, a meniscus negative lens, negative lens, and positive lens having a concave surface on the image side in order from the object side to the image side. The third lens unit L3 is different from that of the first embodiment in that the third lens unit L3 includes a positive lens 61, a negative lens 62, and a positive lens 63. The negative lens 62 of the third lens unit L3 is made of a material of trade name S-LAH79 (νd = 28.3, Θg, F = 0.598) manufactured by OHARA INC. The secondary lens is favorably corrected by using a material with a relatively small partial dispersion ratio as the high dispersion for the negative lens 62.

Next, Example 6 of FIG. 26 will be described. In the zoom lens of Example 6 , the first lens unit L1 having a positive refractive power, the second lens unit L2 having a negative refractive power, and the third lens unit L3 having a positive refractive power in order from the object side to the image side. The fourth lens unit L4 has a negative refractive power, and the fifth lens unit L5 has a positive refractive power.

During zooming from the wide-angle end to the telephoto end, the first lens unit L1 is on the object side, the second lens unit L2 is on the image side, the third lens unit L3 is on the object side, and the fourth lens unit L4 is on the image side. The fifth lens unit L5 has moved to the object side. As a result, the distance between the fourth lens unit L4 and the fifth lens unit L5 is narrower at the telephoto end than at the wide-angle end. The glass block G has an optical path length equivalent to that of the color separation prism and the like, and is thicker than the other embodiments. The third lens unit L3 includes two lenses in three groups, a negative lens 71, a cemented lens including a positive lens 72, and a positive lens 73. The negative lens 71 is trade name S-LAH79 (νd = 28.3, Θg, F = 0.598) manufactured by OHARA INC. The negative lens 71 is a material having a relatively small partial dispersion ratio as high dispersion, and corrects the secondary spectrum favorably by being used for the negative lens.

  The lens configuration of each embodiment is not limited to the moving system of the above embodiment, and the first lens unit and the third lens unit having a positive refractive power may be fixed for zooming.

Next, numerical examples of the zoom lens of the present invention will be shown. Examples 1, 2, Reference Example 1, and Examples 3-6 correspond to Numerical Examples 1-7. In the numerical examples, i indicates the order of the optical surfaces from the object side, Ri is the radius of curvature of the i-th lens surface in order from the object side, Di is the i-th lens thickness and air spacing in order from the object side, Ni And νi are the refractive index and Abbe number of the glass of the i-th lens in order from the object side. Table 1 shows the relationship between the above-described conditional expressions and numerical examples. The partial dispersion ratio Θg, FI is shown only for the negative lens A of the third lens group. The aspherical shape is based on the displacement in the optical axis direction as the X axis, the H axis in the direction perpendicular to the optical axis, the light traveling direction is positive, R is the paraxial radius of curvature, K is the conic constant, A ′, When B ′, C ′, D ′, B, C, D, and E are aspherical coefficients, respectively

+ A′H ³ + BH ⁴ + B′H ⁵ + CH ⁶ + C′H ⁷ + DH ⁸ + D′ H ⁹ + EH ¹⁰
It is expressed by the following formula.

Further, for example, the display of “e-Z” means “10 ^−Z ”. F is a focal length, Fno is an F number, and ω is a half angle of view. In each numerical example, the last two surfaces are glass blocks such as filters.

[Numerical Example 1]
f = 7.42-49.81 Fno = 2.45-3.14 2ω = 74.1 °-12.8 °

R 1 = 60.867 D 1 = 1.80 N 1 = 1.846660 ν 1 = 23.9
R 2 = 39.187 D 2 = 5.30 N 2 = 1.603112 ν 2 = 60.6
R 3 = 418.644 D 3 = 0.20
R 4 = 48.333 D 4 = 3.20 N 3 = 1.603112 ν 3 = 60.6
R 5 = 150.081 D 5 = Variable
R 6 = 56.887 D 6 = 1.10 N 4 = 1.772499 ν 4 = 49.6
R 7 = 9.793 D 7 = 4.58
R 8 = -54.743 D 8 = 0.90 N 5 = 1.719995 ν 5 = 50.2
R 9 = 21.822 D 9 = 1.38
R10 = 31.006 D10 = 3.30 N 6 = 1.846660 ν 6 = 23.9
R11 = -24.564 D11 = 0.53
R12 = -15.952 D12 = 0.80 N 7 = 1.882997 ν 7 = 40.8
R13 = -55.425 D13 = variable
R14 = Aperture D14 = 2.40
R15 = 10.897 D15 = 4.00 N 8 = 1.743300 ν 8 = 49.3
R16 = -29.579 D16 = 4.00 N 9 = 1.647689 ν 9 = 33.8
R17 = 9.522 D17 = 1.42
R18 = 72.553 D18 = 1.16 N10 = 2.003300 ν10 = 28.3
R19 = 23.852 D19 = 4.40 N11 = 1.487490 ν11 = 70.2
R20 = -22.225 D20 = 2.00
R21 = 20.206 D21 = 3.00 N12 = 1.487490 ν12 = 70.2
R22 = -166.360 D22 = variable
R23 = 25.324 D23 = 2.80 N13 = 1.772499 ν13 = 49.6
R24 = -53.348 D24 = 0.90 N14 = 1.846660 ν14 = 23.9
R25 = 250.592 D25 = variable
R26 = ∞ D26 = 2.40 N15 = 1.516330 ν15 = 64.1
R27 = ∞

\ Focal length 7.42 20.40 49.81
Variable interval \
D 5 1.50 20.10 34.81
D13 19.97 6.94 1.30
D22 1.66 13.11 23.30
D25 5.00 5.67 3.55

Aspheric coefficient
R10 k = -7.17899e + 00 B = 8.46885e-05 C = -3.33220e-07 D = -7.27660e-10
E = -1.32077e-11
R11 k = -2.53914e-01 B = -5.82787e-06 C = -2.30584e-07 D = -5.10167e-09
E = 1.70407e-11
R15 k = -4.51997e-01 B = -3.07120e-05 C = 3.11687e-08 D = 0.00000e + 00
E = 0.00000e + 00

[Numerical Example 2]
f = 7.41-49.76 Fno = 2.45-3.14 2ω = 74.2 °-12.8 °

R 1 = 60.391 D 1 = 1.80 N 1 = 1.846660 ν 1 = 23.9
R 2 = 39.348 D 2 = 5.30 N 2 = 1.603112 ν 2 = 60.6
R 3 = 372.414 D 3 = 0.20
R 4 = 48.834 D 4 = 3.20 N 3 = 1.603112 ν 3 = 60.6
R 5 = 148.809 D 5 = Variable
R 6 = 55.691 D 6 = 1.10 N 4 = 1.772499 ν 4 = 49.6
R 7 = 9.837 D 7 = 4.46
R 8 = -64.785 D 8 = 0.90 N 5 = 1.719995 ν 5 = 50.2
R 9 = 21.479 D 9 = 1.38
R10 = 30.601 D10 = 3.30 N 6 = 1.846660 ν 6 = 23.9
R11 = -24.721 D11 = 0.53
R12 = -15.784 D12 = 0.80 N 7 = 1.882997 ν 7 = 40.8
R13 = -57.872 D13 = Variable
R14 = Aperture D14 = 2.40
R15 = 10.942 D15 = 5.00 N 8 = 1.743300 ν 8 = 49.3
R16 = -31.848 D16 = 3.00 N 9 = 1.647689 ν 9 = 33.8
R17 = 9.569 D17 = 1.41
R18 = 73.381 D18 = 1.00 N10 = 2.003300 ν10 = 28.3
R19 = 25.459 D19 = 4.40 N11 = 1.496999 ν11 = 81.5
R20 = -22.737 D20 = 2.00
R21 = 20.362 D21 = 3.00 N12 = 1.487490 ν12 = 70.2
R22 = -234.301 D22 = variable
R23 = 25.885 D23 = 3.00 N13 = 1.772499 ν13 = 49.6
R24 = -48.420 D24 = 0.90 N14 = 1.846660 ν14 = 23.9
R25 = 806.972 D25 = variable
R26 = ∞ D26 = 2.40 N15 = 1.516330 ν15 = 64.1
R27 = ∞

\ Focal length 7.41 20.78 49.76
Variable interval \
D 5 1.50 20.68 35.27
D13 20.23 6.56 1.01
D22 2.43 13.24 23.01
D25 5.00 6.25 4.53

Aspheric coefficient
R10 k = -8.08213e + 00 B = 7.85119e-05 C = -1.85039e-07 D = -4.85066e-09
E = 4.29041e-11
R11 k = -3.50553e-01 B = -1.82078e-05 C = -9.87066e-08 D = -9.37907e-09
E = 7.81990e-11
R15 k = -4.52946e-01 B = -2.97445e-05 C = 5.14379e-08 D = 0.00000e + 00
E = 0.00000e + 00

[Numerical Example 3]
f = 7.40-49.79 Fno = 2.45-3.17 2ω = 74.2 °-12.8 °

R 1 = 65.191 D 1 = 1.80 N 1 = 1.846660 ν 1 = 23.9
R 2 = 40.823 D 2 = 5.30 N 2 = 1.603112 ν 2 = 60.6
R 3 = 683.073 D 3 = 0.20
R 4 = 50.030 D 4 = 3.20 N 3 = 1.603112 ν 3 = 60.6
R 5 = 158.327 D 5 = Variable
R 6 = 69.953 D 6 = 1.10 N 4 = 1.772499 ν 4 = 49.6
R 7 = 9.044 D 7 = 5.40
R 8 = -41.303 D 8 = 0.90 N 5 = 1.743997 ν 5 = 44.8
R 9 = 30.183 D 9 = 0.25
R10 = 39.230 D10 = 3.30 N 6 = 1.846660 ν 6 = 23.9
R11 = -23.968 D11 = 0.55
R12 = -15.318 D12 = 0.80 N 7 = 1.882997 ν 7 = 40.8
R13 = -27.956 D13 = variable
R14 = Aperture D14 = 0.80
R15 = 9.075 D15 = 4.00 N 8 = 1.743300 ν 8 = 49.3
R16 = -126.862 D16 = 4.00 N 9 = 1.806100 ν 9 = 33.3
R17 = 8.141 D17 = 1.57
R18 = 36.369 D18 = 1.00 N10 = 1.603420 ν10 = 38.0
R19 = 13.766 D19 = 4.40 N11 = 1.496999 ν11 = 81.5
R20 = -21.700 D20 = 2.00
R21 = 15.685 D21 = 3.00 N12 = 1.496999 ν12 = 81.5
R22 = 69.573 D22 = variable
R23 = 22.235 D23 = 4.00 N13 = 1.772499 ν13 = 49.6
R24 = -27.099 D24 = 0.90 N14 = 1.846660 ν14 = 23.9
R25 = 5461.127 D25 = variable
R26 = ∞ D26 = 2.40 N15 = 1.516330 ν15 = 64.1
R27 = ∞


\ Focal length 7.40 20.82 49.79
Variable interval \
D 5 1.50 21.95 35.88
D13 19.69 7.09 1.42
D22 1.96 13.13 23.14
D25 5.00 4.95 2.35

Aspheric coefficient
R10 k = -9.11623e + 00 B = 8.43674e-05 C = 2.03964e-07 D = 7.73046e-09
E = -3.40062e-10
R11 k = 6.28631e + 00 B = 4.19463e-05 C = 7.32183e-07 D = -3.87583e-09
E = -1.21361e-10
R15 k = -4.18532e-01 B = -2.22198e-05 C = 9.08447e-08 D = 0.00000e + 00
E = 0.00000e + 00

[Numerical Example 4 ]
f = 7.40-49.79 Fno = 2.45-3.37 2ω = 74.2 °-12.8 °

R 1 = 67.958 D 1 = 1.80 N 1 = 1.846660 ν 1 = 23.9
R 2 = 40.649 D 2 = 5.50 N 2 = 1.603112 ν 2 = 60.6
R 3 = 858.539 D 3 = 0.20
R 4 = 46.066 D 4 = 3.30 N 3 = 1.603112 ν 3 = 60.6
R 5 = 151.771 D 5 = variable
R 6 = 74.979 D 6 = 1.10 N 4 = 1.772499 ν 4 = 49.6
R 7 = 8.930 D 7 = 5.33
R 8 = -55.569 D 8 = 0.90 N 5 = 1.806098 ν 5 = 40.9
R 9 = 32.588 D 9 = 0.25
R10 = 40.466 D10 = 3.30 N 6 = 1.846660 ν 6 = 23.9
R11 = -22.739 D11 = 0.61
R12 = -14.581 D12 = 0.80 N 7 = 1.882997 ν 7 = 40.8
R13 = -30.718 D13 = variable
R14 = Aperture D14 = 0.80
R15 = 9.714 D15 = 4.00 N 8 = 1.743300 ν 8 = 49.3
R16 = 36.804 D16 = 4.00 N 9 = 2.003300 ν 9 = 28.3
R17 = 9.343 D17 = 1.25
R18 = 35.677 D18 = 5.40 N10 = 1.496999 ν10 = 81.5
R19 = -19.905 D19 = 2.00
R20 = 17.166 D20 = 3.00 N11 = 1.487490 ν11 = 70.2
R21 = 81.806 D21 = variable
R22 = 24.402 D22 = 4.00 N12 = 1.772499 ν12 = 49.6
R23 = -28.644 D23 = 0.90 N13 = 1.922860 ν13 = 18.9
R24 = -325.677 D24 = variable
R25 = ∞ D25 = 2.40 N14 = 1.516330 ν14 = 64.1
R26 = ∞

\ Focal length 7.40 21.54 49.79
Variable interval \
D 5 1.00 21.60 34.61
D13 22.75 8.61 2.92
D21 6.20 16.22 25.46
D24 5.00 6.14 4.33

Aspheric coefficient
R10 k = 4.73026e + 00 B = 6.80111e-05 C = -1.90565e-07 D = 3.41468e-09
E = -1.11868e-11
R11 k = 1.60490e + 00 B = 1.07600e-05 C = -1.80049e-07 D = -3.93171e-09
E = 2.77776e-11
R15 k = -4.16400e-01 B = -1.63805e-05 C = 8.95486e-08 D = 0.00000e + 00
E = 0.00000e + 00

[Numerical Example 5 ]
f = 7.41-49.76 Fno = 2.45-3.14 2ω = 74.2 °-12.8 °

R 1 = 62.198 D 1 = 1.80 N 1 = 1.846660 ν 1 = 23.9
R 2 = 39.904 D 2 = 5.30 N 2 = 1.603112 ν 2 = 60.6
R 3 = 561.465 D 3 = 0.20
R 4 = 51.676 D 4 = 3.20 N 3 = 1.603112 ν 3 = 60.6
R 5 = 168.814 D 5 = Variable
R 6 = 76.445 D 6 = 1.10 N 4 = 1.772499 ν 4 = 49.6
R 7 = 9.604 D 7 = 4.53
R 8 = -80.828 D 8 = 0.90 N 5 = 1.743997 ν 5 = 44.8
R 9 = 25.586 D 9 = 1.38
R10 = 33.444 D10 = 3.30 N 6 = 1.846660 ν 6 = 23.9
R11 = -22.591 D11 = 0.30
R12 = -16.830 D12 = 0.80 N 7 = 1.882997 ν 7 = 40.8
R13 = -75.117 D13 = Variable
R14 = Aperture D14 = 2.40
R15 = 10.589 D15 = 4.00 N 8 = 1.743300 ν 8 = 49.3
R16 = 2031.389 D16 = 4.00 N 9 = 1.672700 ν 9 = 32.1
R17 = 9.417 D17 = 1.38
R18 = 55.536 D18 = 1.16 N10 = 2.003300 ν10 = 28.3
R19 = 30.869 D19 = 4.40 N11 = 1.496999 ν11 = 81.5
R20 = -23.001 D20 = 2.00
R21 = 20.478 D21 = 3.00 N12 = 1.487490 ν12 = 70.2
R22 = -518.854 D22 = variable
R23 = 23.937 D23 = 2.80 N13 = 1.772499 ν13 = 49.6
R24 = -101.645 D24 = 0.90 N14 = 1.846660 ν14 = 23.9
R25 = 131.019 D25 = variable
R26 = ∞ D26 = 2.40 N15 = 1.516330 ν15 = 64.1
R27 = ∞

\ Focal length 7.41 20.07 49.76
Variable interval \
D 5 1.50 20.39 35.65
D13 20.49 7.18 1.00
D22 1.37 11.98 21.62
D25 5.00 5.26 2.87

Aspheric coefficient
R10 k = -1.11862e + 01 B = 8.65350e-05 C = -3.62465e-07 D = 1.05864e-08
E = -4.46762e-10
R11 k = -8.21740e-01 B = -1.80820e-05 C = 9.96845e-08 D = -1.45132e-08
E = -1.11035e-10
R15 k = -5.02012e-01 B = -1.87507e-05 C = 8.73716e-08 D = 0.00000e + 00
E = 0.00000e + 00

[Numerical Example 6 ]
f = 6.74-64.80 Fno = 2.88-3.13 2ω = 52.9 °-5.9 °

R 1 = 47.310 D 1 = 1.30 N 1 = 1.846660 ν 1 = 23.9
R 2 = 29.094 D 2 = 5.00 N 2 = 1.487490 ν 2 = 70.2
R 3 = -4034.398 D 3 = 0.20
R 4 = 28.453 D 4 = 3.70 N 3 = 1.696797 ν 3 = 55.5
R 5 = 94.268 D 5 = variable
R 6 = 57.709 D 6 = 0.80 N 4 = 1.785896 ν 4 = 44.2
R 7 = 7.491 D 7 = 3.62
R 8 = -28.113 D 8 = 0.70 N 5 = 1.834000 ν 5 = 37.2
R 9 = 26.990 D 9 = 0.86
R10 = 17.245 D10 = 1.90 N 6 = 1.922860 ν 6 = 18.9
R11 = 126.626 D11 = variable
R12 = Aperture D12 = 1.04
R13 = 10.155 D13 = 3.00 N 7 = 1.583126 ν 7 = 59.4
R14 = 90.080 D14 = 2.60
R15 = 20.045 D15 = 0.70 N 8 = 2.003300 ν 8 = 28.3
R16 = 10.467 D16 = 1.10
R17 = 39.936 D17 = 1.60 N 9 = 1.487490 ν 9 = 70.2
R18 = -25.038 D18 = variable
R19 = ∞ D19 = variable
R20 = 18.193 D20 = 2.70 N10 = 1.696797 ν10 = 55.5
R21 = -27.078 D21 = 0.70 N11 = 1.846660 ν11 = 23.9
R22 = 23515.459 D22 = variable
R23 = ∞ D23 = 2.60 N12 = 1.516330 ν12 = 64.1
R24 = ∞

\ Focal length 6.74 21.28 64.80
Variable interval \
D 5 0.92 15.31 26.28
D11 29.16 12.02 3.80
D18 2.30 2.30 2.30
D19 1.89 1.57 7.27
D22 5.00 9.31 3.05

Aspheric coefficient
R13 k = 2.23526e-01 B = -1.31600e-05 C = 2.00597e-05 D = 2.17778e-07
E = -2.26333e-10

[Numerical Example 7 ]
f = 10.70 to 50.94 Fno = 2.47 to 3.13 2ω = 73.6 ° to 17.9 °

R 1 = 87.732 D 1 = 2.20 N 1 = 1.846660 ν 1 = 23.9
R 2 = 63.233 D 2 = 8.00 N 2 = 1.487490 ν 2 = 70.2
R 3 = 641.376 D 3 = 0.20
R 4 = 58.183 D 4 = 5.00 N 3 = 1.696797 ν 3 = 55.5
R 5 = 132.663 D 5 = Variable
R 6 = 69.387 D 6 = 1.50 N 4 = 1.743997 ν 4 = 44.8
R 7 = 12.542 D 7 = 7.70
R 8 = -87.184 D 8 = 1.20 N 5 = 1.712995 ν 5 = 53.9
R 9 = 31.114 D 9 = 0.20
R10 = 19.841 D10 = 4.80 N 6 = 1.805181 ν 6 = 25.4
R11 = 204.668 D11 = 0.70
R12 = -166.551 D12 = 1.05 N 7 = 1.603420 ν 7 = 38.0
R13 = 46.363 D13 = variable
R14 = Aperture D14 = 1.40
R15 = -29.974 D15 = 0.70 N 8 = 2.003300 ν 8 = 28.3
R16 = 36.573 D16 = 3.80 N 9 = 1.806098 ν 9 = 40.9
R17 = -21.759 D17 = 0.12
R18 = 37.569 D18 = 3.20 N10 = 1.719995 ν10 = 50.2
R19 = -70.150 D19 = variable
R20 = -31.089 D20 = 2.05 N11 = 1.846660 ν11 = 23.9
R21 = -17.262 D21 = 0.75 N12 = 1.638539 ν12 = 55.4
R22 = 4911.493 D22 = Variable
R23 = -201.546 D23 = 3.00 N13 = 1.583126 ν13 = 59.4
R24 = -47.511 D24 = 1.40
R25 = -28.970 D25 = 1.10 N14 = 1.846660 ν14 = 23.9
R26 = -371.076 D26 = 5.40 N15 = 1.516330 ν15 = 64.1
R27 = -25.270 D27 = 0.20
R28 = 86.741 D28 = 5.60 N16 = 1.438750 ν16 = 95.0
R29 = -35.679 D29 = 0.20
R30 = 91.355 D30 = 3.80 N17 = 1.438750 ν17 = 95.0
R31 = -90.021 D31 = 2.00
R32 = ∞ D32 = 30.00 N18 = 1.516330 ν18 = 64.1
R33 = ∞

\ Focal length 10.70 21.10 50.94
Variable interval \
D 5 1.30 21.84 44.16
D13 31.11 15.68 4.38
D19 2.41 10.83 23.52
D22 25.03 16.61 3.92
D31 2.00 4.66 7.44
Aspheric coefficient
R23 k = 1.65044e + 02 B = -1.19664e-05 C = 8.10561e-09 D = -7.88905e-11
E = 3.12444e-13

  Each embodiment is compatible with high-pixel digital cameras and video cameras with high zoom ratio, compact size, spherical aberration, coma, and field curvature corrected well, and with the secondary spectrum of axial chromatic aberration corrected well. Achieving high-performance zoom lenses that are possible.

  Next, an embodiment of a digital camera (imaging device) using the zoom lens of the present invention as a photographing optical system will be described with reference to FIG.

  In FIG. 31, 20 is a digital camera body, 21 is a photographing optical system constituted by the zoom lens of the present invention, 22 is an image pickup device such as a CCD for receiving a subject image by the photographing optical system 21, and 23 is picked up by the image pickup device 22. A recording means 24 for recording the subject image, and a viewfinder 24 for observing the subject image displayed on a display element (not shown).

  The display element is constituted by a liquid crystal panel or the like, and a subject image formed on the image sensor 22 is displayed.

  Thus, by applying the zoom lens of the present invention to an imaging apparatus such as a digital camera, an imaging apparatus having a small size and high optical performance is realized.

  Next, an embodiment of a camera (imaging device) using the zoom lens of the present invention as a photographing optical system will be described with reference to FIG.

  In FIG. 32, 10 is a video camera body, 11 is a photographing optical system constituted by the zoom lens of the present invention, 12 is an image sensor such as a CCD that receives a subject image by the photographing optical system 11, and 13 is received by the image sensor 12. A recording unit 14 for recording a subject image is a finder for observing the subject image displayed on a display element (not shown). The display element is constituted by a liquid crystal panel or the like, and a subject image formed on the image sensor 12 is displayed.

  Thus, by applying the zoom lens of the present invention to an image pickup apparatus such as a video camera, a small-size image pickup apparatus having high optical performance is realized.

Schematic diagram of paraxial refractive power arrangement of variable magnification optical system in the present invention Lens sectional view of Example 1 Aberration diagram at the wide-angle end of Example 1 Aberration diagram at the intermediate position of Example 1 Aberration diagram at telephoto end of Example 1 Lens sectional view of Example 2 Aberration diagrams at the wide-angle end of Example 2 Aberration diagram at intermediate position of Example 2 Aberration diagrams at the telephoto end of Example 2 Lens cross section of Reference Example 1 Aberration diagram at the wide-angle end of Reference Example 1 Aberration diagram at intermediate position in Reference Example 1 Aberration diagram at the telephoto end of Reference Example 1 Lens sectional view of Example 3 Aberration diagrams at the wide-angle end of Example 3 Aberration diagrams at the intermediate position of Example 3 Aberration diagrams at the telephoto end of Example 3 Lens sectional view of Example 4 Aberration diagrams at the wide-angle end of Example 4 Aberration diagrams at the intermediate position of Example 4 Aberration diagrams at the telephoto end of Example 4 Lens sectional view of Example 5 Aberration diagrams at the wide-angle end of Example 5 Aberration diagrams at the intermediate position of Example 5 Aberration diagrams at the telephoto end of Example 5 Lens sectional view of Example 6 Aberration diagrams at the wide-angle end of Example 6 Aberration diagram at intermediate position of Example 6 Aberration diagrams at the telephoto end of Example 6 The graph which shows the relationship between Abbe number (nu) d and partial dispersion ratio (theta) g, F. Schematic when the zoom lens of the present invention is applied to a digital camera Schematic when the zoom lens of the present invention is applied to a video camera

L1 ... 1st lens group L2 ... 2nd lens group L3 ... 3rd lens group L4 ... 4th lens group L5 ... 5th lens group SP ... Aperture IP ... Image plane d ... d line g ... g line C ... C line F ... F line ΔM ... Meridional image plane ΔS ... Sagittal image plane G ... Glass block

Claims (12)

In order from the object side to the image side, the lens unit includes a first lens unit having a positive refractive power, a second lens unit having a negative refractive power, a third lens unit having a positive refractive power, and a fourth lens group having a positive refractive power. , at the telephoto end than at the wide-angle end, wherein the first lens group distance between the second lens group becomes large, Ri said that the second lens group distance between the third lens group is narrowed, the third lens group in a fourth lens group of the zoom lens distance for zooming by changing the distance between each lens group so that the wider, the third lens group, Nyudi3n an Abbe number, when the partial dispersion ratio and ShitagF3n,
10 <νd3n ≦ 28.3
−0.0027νd3n + 0.620 <θgF3n <−0.0027νd3n + 0.680
A zoom lens comprising a negative lens made of a material that satisfies the following conditions: In order from the object side to the image side, a first lens group having a positive refractive power, a second lens group having a negative refractive power, a third lens group having a positive refractive power, a fourth lens group having a negative refractive power, and a positive lens is composed of a fifth lens group having a refractive power, at the telephoto end than at the wide-angle end, wherein the first lens group distance between the second lens group becomes large, the interval of the third lens group and the second lens group tends to close, the third lens wherein becomes distance of the fourth lens group is large and groups, by changing the distance between the lens units such that the distance between the fourth lens group and the fifth lens group becomes narrow zooming in the zoom lens to perform, the third lens group, Nyudi3n an Abbe number, when the partial dispersion ratio and ShitagF3n,
10 <νd3n ≦ 28.3
−0.0027νd3n + 0.620 <θgF3n <−0.0027νd3n + 0.680
A zoom lens comprising a negative lens made of a material that satisfies the following conditions: When the focal length of the negative lens is f3n, the focal length of the third lens group is f3, and the focal length of the entire system at the telephoto end is ft .
0.2 <| f3n | / f3 <3.5
0.2 <f3 / ft <0.8
The zoom lens according to claim 1 , wherein the zoom lens satisfies the following. The third lens group has an Abbe number of νd3p and a partial dispersion ratio of θgF3p.
−0.0030 <(θgF3n−θgF3p) / (νd3n−νd3p)
The zoom lens according to any one of claims 1 to 3, characterized in that it has a positive lens made of a material that satisfies the following condition. When the refractive index of the negative lens material is N3n,
1.80 <N3n
The zoom lens according to any one of claims 1 to 4, characterized by satisfying the following condition. When the negative lens has a concave surface in contact with air, the radius of curvature of the concave surface of the negative lens is R3n, the focal length of the third lens group is f3, and the focal length of the entire system at the telephoto end is ft.
0.2 <| R3n | / f3 <1.2
0.2 <f3 / ft <0.8
The zoom lens according to any one of claims 1 to 5, characterized by satisfying the following condition. When the negative lens constitutes a part of the cemented lens, which f3n the focal length of the negative lens, and f3s the focal length of the cemented lens,
0.01 <| f3n | / f3s <1.5
The zoom lens according to any one of claims 1 to 6, characterized by satisfying the following condition. The cemented lens includes a positive lens, and when the Abbe number of the material constituting the positive lens is νd3 ps and the partial dispersion ratio is θgF3 ps,
−0.0030 <(θgF3n−θgF3ps) / (νd3n−νd3ps)
The zoom lens according to claim 7 , wherein the following condition is satisfied. When the focal length of the first lens group is f1, and the focal length of the entire system at the telephoto end is ft,
0.5 <f1 / ft <2.2
The zoom lens according to any one of claims 1 to 8, characterized by satisfying the following condition. When the focal length of the second lens group is f2, and the focal length of the entire system at the telephoto end is ft,
0.1 <| f2 | / ft <0.4
The zoom lens according to any one of claims 1 to 9, characterized by satisfying the following condition. Any zoom lens according to one of claims 1 to 10 and forming an image on a solid-state image device. And any one of the zoom lens according to claim 1 to 11, an imaging apparatus characterized by comprising a solid-state image sensor for receiving an image formed by the zoom lens.