JP2012123030A - Zoom lens and optical apparatus having the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a compact zoom lens which has excellent optical performance all over the zoom area and all over the object distance, has a wide angle and a high variable power ratio, and has small variation of F-number, and to provide an optical apparatus having the same.SOLUTION: The zoom lens has at least a first lens group having a negative refractive power and a second lens group having a positive refractive power, and achieves a wide angle and a high variable power ratio and a compact size, and small variation of F-number by properly using first F-number determination means and second F-number determination means for each zoom position.

Description

  The present invention relates to a zoom lens suitable for a still camera, a video camera, a digital still camera, and the like, and an optical apparatus having the same.

  Recently, with the enhancement of functions of imaging devices (cameras) such as video cameras and digital still cameras using solid-state imaging devices, a zoom lens with a large aperture ratio that includes a wide angle of view is required for the optical system used therefor. Yes.

  In this type of camera, various optical members such as a low-pass filter and a color correction filter are arranged between the last lens part and the image sensor, so that the optical system used therefor has a lens system with a relatively long back focus. Required.

  In the case of a color camera using a color image pickup device, in order to avoid color shading, an optical system having good image side telecentric characteristics is desired to be used.

  Furthermore, with the recent reduction in size and magnification of digital cameras, negative lead type zoom lenses that tend to reduce the front lens diameter tend to increase F-number fluctuations when magnification is increased.

  In general, when the zooming F number is determined at either the wide-angle end or the telephoto end, the other is determined subordinately.

  Therefore, if the F-number at the wide-angle end is set to a brightness that does not cause a problem in product specifications, there is a problem that the F-number at the telephoto end becomes dark.

  Also, if the telephoto end F-number is sufficiently bright, the wide-angle end F-number will be brighter than necessary, leading to an increase in the size of the optical system.

  In zoom lenses that change magnification by moving at least one lens group during zooming, the F-number fluctuation at the telephoto end is reduced by changing the aperture diameter of the aperture stop at the wide-angle end and the telephoto end, respectively. Patent Document 1 is known.

  Further, as a zoom lens having a small overall system, a long back focus, and good telecentric characteristics on the image side, in order from the object side to the image side, a first lens group having a negative refractive power and a second lens group having a positive refractive power Patent Document 2 is known as an embodiment of a three-group zoom lens having a small F-number variation at the time of zooming.

  Further, in order from the object side to the image side, in the three-group zoom lens including the first lens group having a negative refractive power, the second lens group having a positive refractive power, and the third lens group having a positive refractive power, Patent Documents 3 and 4 are known as embodiments in which doubling is achieved.

JP 2007-260305 A JP 2004-013130 A JP 2006-208890 JP JP 2006-227197

  In a negative lead type zoom lens, it is effective to reduce the amount of movement of the main zoom lens group in order to reduce the F number fluctuation at the time of zooming with a small size and wide angle.

  However, when trying to achieve a high zoom ratio, the amount of movement of the main zoom lens group increases, so the F-number fluctuation during zooming increases.

  Here, if the refractive power of each lens unit is simply increased in order to suppress the F-number variation, the amount of movement of the main variable magnification lens unit is reduced, aberration variation accompanying zooming increases, and high optical performance over the entire zoom range It becomes difficult to get.

  For this reason, in order to achieve a zoom lens with a negative lead type zoom lens that is small and wide-angle, has a high zoom ratio, and small F-number fluctuation, the refractive power of each lens group must be optimized and each zoom position must be optimized. It is important to use different methods to determine the F number.

  When optimizing the refractive power of each lens group, if the size and the wide angle are reduced without properly arranging the F-number determining means at the wide-angle end, the refractive power of the first lens group is strengthened in order to reduce the size. There must be.

  As a result, there is a problem in that the optical performance at the wide-angle end cannot be corrected satisfactorily.

  In addition, when attempting to increase the magnification and suppress the F number fluctuation without properly arranging the F number determination means at the telephoto end, one of the following must be selected.

  One is a method in which the refractive power of the lens group is excessively increased in order to increase the change in the imaging magnification of the main variable magnification group more than necessary.

  This has a problem in that the curvature radius of each lens becomes tight and good optical performance cannot be obtained.

  The second method is to increase the amount of movement of the lens group.

  Increasing the amount of movement of the lens group provides a high zoom ratio, but has a problem in that F-number fluctuation increases and the F-number at the telephoto end becomes dark.

  In addition, since it is necessary to secure a sufficient lens interval at the wide angle end so that the first lens group and the second lens group at the telephoto end do not interfere with each other, an increase in the overall length is also caused.

  In Patent Documents 1 and 2, the F-number fluctuation is small, but the zoom ratio is also small. Therefore, when trying to achieve a high zoom ratio, there is a concern that the F-number will drop at the telephoto end.

  Patent Documents 3 and 4 have a problem in that the number of components is small and the zoom ratio is high, but the F number variation is large.

  An object of the present invention is to provide a zoom lens in which the entire lens system is small, wide-angle, and has a high zoom ratio and small F-number fluctuation, and an image pickup apparatus having the same.

In order from the object side, it has at least two lens groups of a first lens group having a negative refractive power and a second lens group having a positive refractive power,
Having a first F number determination means and a second F number determination means;
A zoom lens satisfying the following conditional expression, where S12 is a distance between the first F-number determining means and the second F-number determining means and f2 is a focal length of the second lens group.
0.3 <S12 / f2 <0.9 (1)

  According to the present invention, by effectively introducing an aspheric surface into the lens group, various off-axis aberrations, in particular, curvature of field at the wide-angle end and spherical aberration when the aperture ratio is increased can be effectively corrected. The effect is obtained.

Lens sectional view of Embodiment 1 of the present invention Aberration diagram at the wide-angle end according to the first embodiment of the present invention. Aberration diagram in the middle of Embodiment 1 of the present invention Aberration diagram at the telephoto end according to the first embodiment of the present invention. Lens sectional drawing of Embodiment 2 of the present invention Aberration diagram at wide-angle end according to Embodiment 2 of the present invention Aberration diagram in the middle of Embodiment 2 of the present invention Aberration diagram at the telephoto end according to Embodiment 2 of the present invention Lens sectional drawing of Embodiment 3 of the present invention Aberration diagram at wide-angle end according to Embodiment 3 of the present invention Aberrations in the middle of Embodiment 3 of the present invention Aberration diagram at telephoto end according to Embodiment 3 of the present invention Lens sectional drawing of Embodiment 4 of the present invention Aberration diagram at wide-angle end according to Embodiment 4 of the present invention Aberrations in the middle of Embodiment 4 of the present invention Aberration diagram at telephoto end according to Embodiment 4 of the present invention Lens sectional drawing of Embodiment 5 of the present invention Aberration diagram at wide-angle end according to Embodiment 5 of the present invention Aberrations in the middle of Embodiment 5 of the present invention Aberration diagram at telephoto end according to Embodiment 5 of the present invention Schematic diagram of essential parts of the optical apparatus of the present invention

  FIG. 1 is a lens cross-sectional view of a first embodiment described later of the present invention. 2 to 4 are aberration diagrams at the wide-angle end, the middle, and the telephoto end of Embodiment 1 of the present invention.

  FIG. 5 is a lens cross-sectional view of a second embodiment described later of the present invention. 6 to 8 are aberration diagrams of the second embodiment of the present invention at the wide-angle end, the middle, and the telephoto end.

  FIG. 9 is a lens cross-sectional view of a third embodiment described later of the present invention. 10 to 12 are aberration diagrams of the third embodiment of the present invention at the wide-angle end, the middle, and the telephoto end.

  FIG. 13 is a lens cross-sectional view of a fourth embodiment described later of the present invention. 14 to 16 are aberration diagrams at the wide-angle end, the middle, and the telephoto end of Embodiment 4 of the present invention.

  FIG. 17 is a lens cross-sectional view of a fifth embodiment described later of the present invention. 18 to 20 are aberration diagrams of the fifth embodiment of the present invention at the wide-angle end, the middle, and the telephoto end.

  In the lens cross-sectional view, L1 is a first lens group having a negative refractive power, and L2 is a second lens group having a positive refractive power, which is common to all the embodiments.

  L3 is a third lens unit having a positive refractive power in Examples 2, 3, and 4, and L3 is a third lens group having a negative refractive power in Example 5.

  L4 is a fourth lens unit having a positive refractive power in Examples 4 and 5.

  S1 is a first F number determination means, S2 is a second F number determination means, G is a glass block corresponding to an optical filter, a face plate, an infrared cut filter, and the like, and IP is an image plane.

  Next, the lens configuration of the zoom lens of the present invention will be described.

  In general, when configuring a small wide-angle zoom lens, it is preferable to select a negative lead type preceded by a negative lens group because the back principal point position can be moved to the image side and the back focus can be extended.

  And, in order to realize a good image side telecentric characteristic necessary for an imaging device using a solid-state imaging device or the like, it is necessary to make the lens group closest to the imaging device a positive lens group and to have a role of a field lens. is there.

  Therefore, the zoom lens of the present invention includes at least the first lens unit L1 having a negative refractive power and the second lens unit L2 having a positive refractive power in order from the object side, and at least the second lens unit is moved. , Zooming and accompanying image point movement are corrected.

  Further, as in the present invention, in order to realize an optical system that has a wide-angle compact size and a high zoom ratio and that has a small F-number fluctuation at the time of zooming, the first F-number determining means and the second F-number determining means are used. It is important to use number determining means for each zoom position.

  In general, when the F number determining means cannot be properly used, it is preferable to arrange the F number determining means as close to the first lens as possible in order to reduce the front lens diameter.

  In this case, if the F-number determining means is arranged on the object side of the main zooming group to increase the magnification, the F-number fluctuation increases due to the movement of the main zooming group.

  As a result, there is a problem that the F-number at the telephoto end becomes dark.

  Further, when there is one F-number determining means and this means is arranged on the image side of the main zooming group, since the distance from the exit pupil to the imaging plane is short, the F-number determining means is on the front side of the main zooming group. Compared with the case where the position is set, when the telephoto end is set to the same brightness, the aperture diameter of the F number determination means can be set small.

  However, when a small stop is used in this state, the amount of off-axis light passing through the vertical line is biased (a so-called single stop), leading to a shortage of peripheral light at the wide-angle end.

  In the present invention, the first F-number determining means and the second F-number determining means are appropriately arranged, and the F-number determining means is properly used for each zoom position, thereby suppressing the F-number fluctuation during zooming.

  Specifically, in the zoom lens of the present invention, in order to obtain good optical performance or to reduce the size of the entire lens system, it is necessary to arrange F number determination means so as to satisfy the following conditional expression. good.

0.3 <S12 / f2 <0.9 (1)
Here, S12 is the distance between the first F-number determining means and the second F-number determining means, and f2 is the focal length of the second lens group.

  Expression (1) is an expression that defines the relative arrangement of the first F-number determining means and the second F-number determining means.

  If the relative distance between the first F-number determining means and the second F-number determining means is excessively separated beyond the upper limit of the expression (1), the entire optical system is increased in size.

  If the distance between the first F-number determining means and the second F-number determining means is too close beyond the lower limit of the expression (1), the F-number fluctuation will be the same as when the F-number determining means is single. There is a problem in that it cannot be made smaller.

  Furthermore, it is preferable that at least one of the following conditions is satisfied.

-1.0 <Ls1 / Ls2 <0 (2)
1.0 ≦ Ds1 / Ds2 <1.5 (3)
0.6 <Ds2mid / Ds2 ≦ 1.0 (4)
0.5 <f2 / √ (fwxfT) <2.0 (5)
1.8 <| f1 / fw | <3.0 (6)
Nd1> 1.80 (7)
Here, Ls1 is the distance from the most object side surface of the main zooming group to the first F number determining means, Ls2 is the distance from the most object side surface of the main zooming group to the second F number determining means, and the image side A thing located in is considered a plus.

  Ds1 is the aperture diameter of the first F number determining means at the wide angle end, and Ds2 is the aperture diameter of the second F number determining means at the telephoto end.

  Ds2mid is the aperture diameter of the second F-number determining means at the intermediate focal length, fw is the focal length at the wide angle end, fT is the focal length at the telephoto end, and f1 is the focal length of the first lens group.

  Expression (2) is an expression that defines the positional relationship between the first F number determination means and the second F number determination means.

  When the expression (2) exceeds the upper limit value, the first F number is arranged in the same direction as the second F number determining means.

  As a result, there is a problem in that the F-number determining means cannot be used properly for each zoom position, and the desired F-number fluctuation cannot be suppressed.

  When the expression (2) exceeds the lower limit, if the distance from the most object side surface of the main zooming group to the second F-number determining unit is constant, the first F-number determining unit is It will be placed too far away from the object side.

  Generally, near the wide-angle end, the height of the off-axis ray is higher than the height of the on-axis ray with respect to the optical axis, so the F number is determined, that is, if the on-axis ray is reduced, the off-axis ray must be cut off excessively. It will be good.

  As a result, the peripheral light amount is insufficient near the wide-angle end.

  Formula (3) is a formula which prescribes | regulates the opening diameter of the 1st F number determination means in a wide angle end.

  If the upper limit value of the expression (3) is exceeded, the opening diameter of the first F-number determining means at the wide angle end becomes excessively large.

  As a result, at the wide angle end, the F number cannot be determined by the first F number determining means, and the F number is determined by the second F number determining means.

  When the F number is determined by the second F number determination means at the wide angle end, the distance from the first lens group to the F number determination means becomes long, and thus there is a problem in reducing the front lens diameter.

  When the lower limit of Expression (3) is exceeded, there is a problem that the opening diameter of the first F-number determining means at the wide-angle end becomes excessively small and the F-number becomes dark at the wide-angle end.

  Expression (4) is an expression that defines the aperture diameter of the second F number determination means at the intermediate focal length.

  When the upper limit of Expression (4) is exceeded, that is, when Expression (4) exceeds 1, the second F-number determining means widens the aperture diameter at the intermediate focal length than at the telephoto end.

  In the present invention, when switching between the first F number determination means and the second F number determination means, the opening diameter of the first F number determination means is widened, and the F number is determined by the second F number determination means.

  In other words, when the first F-number determining means is fully opened, the F-number becomes excessively bright at the intermediate focal length, which makes it difficult to correct spherical aberration and coma aberration at the intermediate focal length. .

  If the lower limit value of Expression (4) is exceeded, the F number at the intermediate focal length becomes excessively dark, so that there is a problem in that the continuity of the F number change cannot be maintained.

  Expression (5) is an expression defining the refractive power of the second lens group.

  If the upper limit of Expression (5) is exceeded, the focal length of the second lens group becomes long, that is, the refractive power of the second lens group becomes small, and in order to obtain a desired high zoom ratio, the second lens group The amount of group movement must be increased.

  As a result, there is a problem in that the optical total length when retracted becomes long.

  When the lower limit of Expression (5) is exceeded, the focal length of the second lens group becomes short, that is, the refractive power of the second lens group becomes large, and there is a problem in correcting spherical aberration and coma aberration in the entire zoom range.

  Expression (6) defines the refractive power of the first lens group.

  If the upper limit of Expression (6) is exceeded, the focal length of the first lens group becomes long, that is, the refractive power of the first lens group is too weak, and there is a problem in terms of reducing the front lens diameter.

  When the lower limit of Expression (6) is exceeded, the focal length of the first lens group becomes small, that is, the refractive power of the first lens group is too strong, and the Petzval sum increases to the negative side, particularly at the wide-angle end. There is a problem in that the curvature of field increases.

  Expression (7) is an expression defining the average refractive index of the first lens group.

  When the lower limit of Expression (7) is exceeded, when the refractive power of the first lens group is increased, the radius of curvature of the first lens group becomes tight.

  At this time, if an attempt is made to secure the edge thickness of the lens, the axial thickness of the lens increases, which causes a problem in terms of thinning.

  More preferably, the numerical range is set as follows.

0.45 <S12 / f2 <0.80 (1a)
Furthermore, it is preferable to satisfy at least one conditional expression in which a numerical range is set as follows.

-0.80 <Ls1 / Ls2 <0 (2a)
1.0 ≦ Ds1 / Ds2 <1.3 (3a)
0.7 <Ds2mid / Ds2 ≦ 1.0 (4a)
0.7 <f2 / √ (fwxfT) <1.5 (5a)
2.0 <| f1 / fw | <2.8 (6a)
Nd1> 1.85 (7a)
Next, the F number determination means of each embodiment will be described.

  As for the F-number determining means, all the examples are based on the same idea as in the second example, so only the second example will be described.

  The second exemplary embodiment includes a negative first lens group, a positive second lens group, and a positive third lens group in order from the object side.

  A first F number determining means is disposed between the first lens group and the second lens group, and is used as means for determining the F number at the wide angle end.

  The second F number determining means is disposed between the second lens group and the third lens group, and is used as means for determining the F number at the telephoto end.

  The first F-number determining means and the second F-number are properly used for each zoom position. At the intermediate focal length, the aperture diameter of the second F-number determining means is narrowed to the aperture diameter at the telephoto end. The F number at the time of zooming is changed continuously.

  The second F-number determining means can be arranged in the second lens group as shown in the fourth embodiment.

  Next, the lens configuration of each example will be described.

  Since the first lens group is a common description regardless of the embodiment, the second lens group and the subsequent parts will be described separately.

  In each embodiment, the first lens unit having a negative refractive power is composed of two lenses, a meniscus negative lens having a strong convex surface facing the object side in order from the object side, and a meniscus positive lens having a convex surface facing the object side. Yes.

  Since the first lens group has a large amount of refraction of off-axis rays at the wide-angle end, off-axis aberrations, particularly astigmatism and distortion, are likely to occur.

  Therefore, in this embodiment, the negative lens and the positive lens are configured to suppress the increase in the lens diameter closest to the object side.

  The first lens group is composed of two lenses, both of which are made of a high refractive index glass material, thereby reducing the refractive power of each lens surface and suppressing curvature of field.

  Then, the low-dispersion glass material is used for the negative lens and the high-dispersion glass material is used for the positive lens, thereby correcting the lateral chromatic aberration at the telephoto end and at the wide-angle end.

  In addition, the radius of curvature of the negative meniscus lens is aspherical so that the negative refractive power decreases from the center toward the periphery on the image side, thereby correcting the astigmatism and distortion aberration in a well-balanced manner and reducing the number to two. The first lens group is configured by the number of lenses, contributing to the compactness of the entire lens.

  Next, the second lens group of Example 1 will be described.

  The second lens group of Example 1 has a two-lens configuration of a biconvex positive lens and a meniscus negative lens having a convex surface on the object side, and achieves both a reduction in lens thickness and correction of axial chromatic aberration.

  In addition, spherical aberration and coma are corrected by making the R1 surface of the positive lens and the R2 surface of the negative lens aspherical.

  Next, Examples 2 and 3 will be described.

  The second lens group according to the second exemplary embodiment includes, in order from the object side, a second lens group that is a cemented lens of a positive lens having a convex surface directed toward the object side and a negative lens having a concave surface directed toward the image surface side; It is composed of a total of four lenses, a second b lens group that is a cemented lens of a meniscus negative lens having a convex surface and a positive lens having convex surfaces on both sides.

  In the zoom lens of the present invention, the second lens group is composed of the 2a lens group and the 2b lens group to share the increase in the refractive power of the second lens group due to the wide angle and to reduce the eccentricity sensitivity. Have achieved.

  The configuration of the 2a lens group is such that a positive lens is disposed on the object side, the refraction angle of off-axis rays emitted from the first lens group is reduced, and no off-axis aberrations occur.

  The positive lens disposed closest to the object side is a lens having the highest axial light beam and is mainly involved in correcting spherical aberration and coma.

  Therefore, in the present invention, spherical aberration and coma aberration are favorably corrected by making the object side surface of the positive lens disposed closest to the object side an aspherical surface in which the positive refractive power becomes weak in the periphery.

  In addition, the positive lens of the second lens group has a shape with a convex surface facing the object side, and the positive lens of the second lens group has both surfaces convex, so that spherical aberration and astigmatism are corrected well.

  Further, as in the third embodiment, the second lens group can also be configured by four lenses including a biconvex positive single lens, a cemented lens of a positive lens and a negative lens, and a positive single lens.

  The third lens group of Examples 2 and 3 plays a role as a field lens for ensuring telecentricity, and is characterized by being composed of a single positive lens for shortening the axial lens thickness.

  The third lens group is a focus group, and moves from the image side to the object side when focusing from an object at infinity to an object at a short distance.

  When the focusing is performed, the speed of focusing can be increased by appropriately setting the position sensitivity.

  As described above, by making each lens group a lens configuration that achieves both desired refractive power arrangement and aberration correction, the lens system can be made compact while maintaining good performance.

  Next, Example 4 will be described.

  The second lens group of Example 4 includes a biconvex positive single lens and a cemented lens of a biconvex positive lens and a biconcave negative lens.

  In the second lens group, a positive lens is disposed on the object side, and the refraction angle of the off-axis light beam emitted from the first lens group is reduced so that off-axis aberrations do not occur.

  Further, spherical aberration and coma aberration are favorably corrected by making the object side surface of the positive lens disposed closest to the object side an aspherical surface in which the positive refractive power becomes weak in the periphery.

  In Example 4, in order to reduce the thickness of the second lens group, one set of a cemented lens of a positive lens and a negative lens was disposed.

  The third lens group of Example 4 is composed of a positive single lens, and performs variable magnification sharing together with the second lens group.

  In addition, the object side surface of the third lens group is aspherical so that spherical aberration and coma are corrected.

  The fourth lens group of Example 4 serves as a field lens for ensuring telecentricity, and is characterized by being composed of a single positive lens for shortening the axial lens thickness.

  The fourth lens group is a focus group, and moves from the image side to the object side when focusing from an object at infinity to an object at a short distance.

  When the focusing is performed, the speed of focusing can be increased by appropriately setting the position sensitivity.

  Next, Example 5 will be described.

  Since the second lens group of Example 5 has the same configuration as that of Example 2, description thereof is omitted.

  The third lens group of Example 5 is composed of a single negative lens for thinning.

  The third lens group shares the variable magnification with the second lens group, and also functions as a negative lens, thereby expanding the axial beam and suppressing the F-number fluctuation.

  Since the fourth lens group of Example 5 has the same configuration as that of Example 4, the description thereof is omitted.

  Next, an embodiment of the present invention will be described. In each embodiment, r is the radius of curvature of the lens surface at each surface number, d is the lens thickness and air spacing between the next surface numbers, and Nd and νd are the refractive index and Abbe number for the d line, respectively. * Indicates an aspherical surface.

The two surfaces closest to the image side are glass materials such as face plates. K, A4, A6, A8, and A10 are aspheric coefficients. The aspherical shape is defined as x = (h ² / R) / [1+ {1− (1 + k) (h) where x is the displacement in the optical axis direction at the position of the height h from the optical axis with respect to the surface vertex. / R) ² } ^1/2 ]
+ A4h ⁴ + A6h ⁶ + A8h ⁸ + A10h ¹⁰
It is represented by Where R is the radius of curvature.

  Table 1 shows the relationship between each conditional expression described above and each embodiment.

  FIG. 1 shows an optical sectional view of Embodiment 1 of the present invention. The first embodiment is a zoom lens having a zoom ratio of 2.64 times and an aperture ratio of about 3.4 to 4.5. 2 to 4 show aberration diagrams.

  In the present embodiment, during zooming from the wide-angle end to the telephoto end, the first lens group moves back and forth convex toward the image side, and the second lens group moves toward the object side.

  FIG. 5 shows an optical sectional view of Embodiment 2 of the present invention. The second embodiment is a zoom lens having a zoom ratio of 3.77 times and an aperture ratio of about 2.8 to 4.5. Aberration diagrams are shown in FIGS.

  In the present embodiment, during zooming from the wide-angle end to the telephoto end, the first lens group moves back and forth convex toward the image side, the second lens group moves toward the object side, and the third lens group moves toward the image side. ing.

  FIG. 9 shows an optical sectional view of Embodiment 3 of the present invention. The third embodiment is a zoom lens having a zoom ratio of 4.90 times and an aperture ratio of about 2.9 to 5.0. 10 to 12 show aberration diagrams.

  FIG. 13 shows an optical sectional view of Embodiment 4 of the present invention. The fourth embodiment is a zoom lens having a zoom ratio of 5.54 times and an aperture ratio of about 2.6 to 5.5. Aberration diagrams are shown in FIGS.

  FIG. 17 shows an optical sectional view of Embodiment 5 of the present invention. The fifth embodiment is a zoom lens having a zoom ratio of 4.98 times and an aperture ratio of about 2.5 to 6.0. 18 to 20 show aberration diagrams.

  In the first embodiment, during zooming from the wide-angle end to the telephoto end, the first lens group moves back and forth convex toward the image side, and the second lens group moves toward the object side.

  In the second and third embodiments, during zooming from the wide-angle end to the telephoto end, the first lens unit moves back and forth convex toward the image side, the second lens unit moves toward the object side, and the third lens unit moves toward the image side. Has moved to.

  In the fourth and fifth embodiments, during zooming from the wide-angle end to the telephoto end, the first lens unit moves back and forth convex toward the image side, the second lens unit and the third lens unit move toward the object side, The lens group has moved to the image side.

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

  In FIG. 21, reference numeral 40 denotes a video camera body, 41 denotes a photographing optical system constituted by the zoom lens of the present invention, 42 denotes an imaging element such as a CCD that receives a subject image by the photographing optical system 41, and 43 denotes an imaging element 42. A recording means 44 for recording the received 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 42 is displayed. Reference numeral 45 denotes a liquid crystal display panel having a function equivalent to that of the finder.

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

Numerical example 1
Unit mm

Surface data surface number rd nd vd Effective diameter
1 * -548.956 1.00 1.88300 40.8 8.46
2 * 4.010 0.98 6.85
3 6.937 1.31 2.00330 28.3 7.00
4 28.308 (variable) 6.79
5 (S1) ∞ 1.10 (variable)
6 * 3.224 2.29 1.51633 64.1 4.84
7 -9.852 -0.00 4.43
8 13.368 0.81 1.84666 23.8 4.05
9 * 4.538 1.43 3.39
10 (S2) ∞ (variable) (variable)
11 ∞ 0.80 1.51633 64.1 12.00
12 ∞ 0.40 12.00
Image plane ∞

Aspheric data 1st surface
K = 8.86685e + 002 A 4 = 1.67510e-004 A 6 = 1.02797e-005 A 8 = -1.71961e-006 A10 = 4.39047e-008

Second side
K = -2.74055e + 000 A 4 = 4.20997e-003 A 6 = -1.07482e-004 A 8 = -5.62230e-007 A10 = 4.34989e-008

6th page
K = -8.77791e-001 A 4 = 1.58721e-003 A 6 = 5.53606e-005 A 8 = 1.48151e-006 A10 = -9.42658e-007

9th page
K = 0.00000e + 000 A 4 = 4.80602e-003 A 6 = 3.80599e-004 A 8 = 2.22434e-004 A10 = -1.93578e-005

Various data Zoom ratio 2.64
Wide angle Medium Telephoto focal length 5.50 10.00 14.50
F number 3.43 3.59 4.50
Angle of View 32.96 19.62 13.81
Statue height 3.56 3.56 3.56
Total lens length 27.04 23.07 23.55
BF 0.40 0.40 0.40

d 4 10.24 3.07 0.35
d10 6.68 9.88 13.08


Surface number Effective diameter (wide angle) Effective diameter (middle) Effective diameter (telephoto)
5 3.50 10.00 10.00
10 2.98 3.04 3.15

Zoom lens group data group Start surface Focal length Lens configuration length Front principal point position Rear principal point position
1 1 -11.10 3.29 -0.44 -2.76
2 5 7.89 5.62 -0.27 -4.19
3 11 ∞ 0.80 0.26 -0.26

Numerical example 2
Unit mm

Surface data surface number rd nd vd Effective diameter
1 * 48.641 1.50 1.84954 40.1 12.76
2 * 5.525 2.26 9.57
3 9.048 1.43 1.94595 18.0 9.48
4 14.344 (variable) 8.99
5 (S1) ∞ 0.50 (variable)
6 * 4.753 2.10 1.80604 40.8 6.25
7 27.913 0.60 1.69895 30.1 5.71
8 3.945 0.60 5.03
9 8.794 0.50 1.76182 26.5 5.05
10 4.316 2.44 1.63854 55.4 4.95
11 -19.906 0.50 4.93
12 (S2) ∞ (variable) (variable)
13 19.649 1.40 1.63854 55.4 8.90
14 -260.426 (variable) 8.90
15 ∞ 0.80 1.51633 64.1 12.00
16 ∞ 0.40 12.00
Image plane ∞

Aspheric data 1st surface
K = -2.43560e + 001 A 4 = 1.50712e-006 A 6 = 2.85288e-006 A 8 = -4.89300e-008 A10 = 2.54267e-010

Second side
K = -2.32502e + 000 A 4 = 1.29706e-003 A 6 = -1.09355e-005 A 8 = 4.12584e-007 A10 = -5.87065e-009

6th page
K = -4.87890e-001 A 4 = 1.15534e-004 A 6 = 8.47143e-006 A 8 = 9.84755e-008 A10 = 4.75796e-009

Various data Zoom ratio 3.77
Wide angle Medium Telephoto focal length 5.15 12.18 19.40
F number 2.76 3.30 4.50
Angle of view 35.56 17.65 11.30
Image height 3.68 3.88 3.88
Total lens length 36.67 33.63 38.42
BF 0.40 0.40 0.40

d 4 13.74 2.93 -0.07
d12 3.67 11.86 19.84
d14 4.23 3.83 3.63

Surface number Effective diameter (wide angle) Effective diameter (middle) Effective diameter (telephoto)
5 4.80 15.00 15.00
12 5.04 4.50 4.81

Zoom lens group data group Start surface Focal length Lens configuration length Front principal point position Rear principal point position
1 1 -11.86 5.19 0.39 -3.42
2 5 10.41 7.24 0.38 -4.87
3 13 28.67 1.40 0.06 -0.80
4 15 ∞ 0.80 0.26 -0.26


Numerical Example 3
Unit mm

Surface data surface number rd nd vd Effective diameter
1 36.471 1.80 15.04
2 * 6.493 3.00 11.57
3 10.826 1.80 1.92286 18.9 11.70
4 16.728 (variable) 11.12
5 (S1) ∞ 1.00 (variable)
6 * 12.147 1.50 1.69680 55.5 8.33
7 -63.674 0.15 8.27
8 * 7.674 2.70 1.80610 40.7 7.93
9 -14.231 1.90 2.00330 28.3 7.19
10 5.295 1.50 5.55
11 (S2) ∞ 0.97 (variable)
12 20.909 1.67 1.71999 50.2 5.84
13 -33.655 (variable) 5.80
14 8.932 1.70 1.48749 70.2 8.16
15 19.274 (variable) 7.86
16 ∞ 0.80 1.51633 64.1 12.00
17 ∞ 0.40 12.00
Image plane ∞

Aspheric data 2nd surface
K = -1.50827e + 000 A 4 = 4.27117e-004 A 6 = 4.07551e-006 A 8 = -1.20020e-007 A10 = 1.35594e-009

6th page
K = -3.42977e-001 A 4 = -1.05440e-005 A 6 = -9.60781e-009 A 8 = 8.34730e-008 A10 = -6.78383e-010

8th page
K = 1.08550e-002 A 4 = 3.90514e-005 A 6 = 6.32330e-007 A 8 = -8.93398e-010 A10 = -3.89698e-009

Various data Zoom ratio 4.90
Wide angle Medium Telephoto focal length 5.74 16.76 28.11
F number 2.91 3.50 5.00
Angle of view 31.92 12.03 7.24
Statue height 3.57 3.57 3.57
Total lens length 52.62 44.35 51.45
BF 0.40 0.40 0.40

d 4 24.08 4.62 0.54
d13 6.06 17.65 29.23
d15 1.58 1.18 0.78

Surface number Effective diameter (wide angle) Effective diameter (middle) Effective diameter (telephoto)
5 5.72 15.00 15.00
11 4.73 4.23 5.66

Zoom lens group data group Start surface Focal length Lens configuration length Front principal point position Rear principal point position
1 1 -15.01 6.60 0.55 -4.36
2 5 13.23 11.40 -0.42 -8.72
3 14 32.40 1.70 -0.94 -2.02
4 16 ∞ 0.80 0.26 -0.26

Numerical Example 4
Unit mm

Surface data surface number rd nd vd Effective diameter
1 * 38.859 1.80 1.88300 40.8 14.54
2 * 7.035 2.60 11.38
3 11.016 1.39 1.92286 18.9 11.32
4 17.305 (variable) 10.93
5 (S1) ∞ 1.00 (variable)
6 * 9.681 1.88 1.69350 53.2 7.81
7 -794.231 0.20 7.66
8 * 7.685 3.11 1.80610 40.7 7.37
9 -11.688 1.00 2.00330 28.3 6.30
10 5.244 1.82 5.27
11 (S2) ∞ (variable) (variable)
12 * 33.474 1.37 1.71999 50.2 5.95
13 -19.191 (variable) 6.27
14 12.497 1.70 1.48749 70.2 8.18
15 57.217 (variable) 8.00
16 ∞ 0.80 1.51633 64.1 12.00
17 ∞ 0.40 12.00
Image plane ∞

Aspheric data 1st surface
K = -1.41766e-001 A 4 = -5.64368e-005 A 6 = 7.74524e-007 A 8 = -1.34981e-009 A10 = 3.11370e-011

Second side
K = -1.87619e + 000 A 4 = 3.35946e-004 A 6 = 7.31387e-006 A 8 = -2.75328e-007 A10 = 4.39458e-009

6th page
K = -3.02209e-001 A 4 = -3.71525e-005 A 6 = 5.58952e-007

8th page
K = 4.80833e-003 A 4 = 3.02558e-005 A 6 = 1.95294e-006

12th page
K = -4.92459e + 000 A 4 = -2.63805e-005 A 6 = -3.76033e-007 A 8 = -1.83990e-008 A10 = -3.32450e-009

Various data Zoom ratio 5.54
Wide angle Medium Telephoto focal length 5.82 17.45 32.26
F number 2.58 3.51 5.50
Angle of View 31.55 11.57 6.32
Statue height 3.57 3.57 3.57
Total lens length 47.58 41.85 49.85
BF 0.40 0.40 0.40

d 4 21.07 3.34 -0.67
d11 1.17 0.74 0.30
d13 0.77 15.66 30.55
d15 5.49 3.04 0.60

Surface number Effective diameter (wide angle) Effective diameter (middle) Effective diameter (telephoto)
5 5.74 15.00 15.00
11 4.98 4.08 5.44

Zoom lens group data group Start surface Focal length Lens configuration length Front principal point position Rear principal point position
1 1 -16.08 5.79 0.52 -3.80
2 5 18.55 9.01 -8.83 -10.37
3 12 17.13 1.37 0.51 -0.29
4 14 32.39 1.70 -0.32 -1.44
5 16 ∞ 0.80 0.26 -0.26

Numerical Example 5
Unit mm

Surface data surface number rd nd vd Effective diameter
1 * 135.858 1.70 1.85961 40.3 13.12
2 * 5.894 1.79 10.60
3 11.296 2.16 1.84666 23.9 10.97
4 54.071 (variable) 10.55
5 (S1) ∞ 0.50 (variable)
6 * 5.733 2.72 1.85961 40.3 7.08
7 26.269 0.50 1.69895 30.1 6.25
8 4.522 0.67 5.60
9 8.281 0.50 1.69895 30.1 5.64
10 3.659 2.29 1.63854 55.4 5.43
11 -50.835 1.13 5.33
12 (S2) ∞ (variable) (variable)
13 -7.199 0.60 1.48749 70.2 5.25
14 -11.725 (variable) 5.56
15 9.780 1.50 1.80 400 46.6 8.43
16 27.000 (variable) 8.14
17 ∞ 0.80 1.51633 64.1 12.00
18 ∞ 0.40 12.00
Image plane ∞

Aspheric data 1st surface
K = 5.70656e + 001 A 4 = 8.93479e-007 A 6 = -1.65878e-007 A 8 = -6.28046e-009 A10 = -1.88706e-011

Second side
K = -2.29154e + 000 A 4 = 9.71253e-004 A 6 = -1.67254e-005 A 8 = 2.78098e-007 A10 = -3.65321e-009

6th page
K = -2.58378e-001 A 4 = -4.50313e-006 A 6 = -2.33994e-007

Various data Zoom ratio 4.98
Wide angle Medium telephoto focal length 6.00 17.29 29.89
F number 2.52 4.06 6.00
Angle of View 30.62 11.61 6.77
Statue height 3.55 3.55 3.55
Total lens length 46.44 40.82 47.96
BF 0.40 0.40 0.40

d 4 20.12 3.55 -0.25
d12 2.01 3.96 5.90
d14 4.88 14.13 23.38
d16 2.17 1.92 1.67

Surface number Effective diameter (wide angle) Effective diameter (middle) Effective diameter (telephoto)
5 6.29 15.00 15.00
12 4.88 4.35 5.04

Zoom lens group data group Start surface Focal length Lens configuration length Front principal point position Rear principal point position
1 1 -15.19 5.65 -0.37 -4.49
2 5 11.43 8.31 -0.09 -5.95
3 13 -40.00 0.60 -0.67 -1.09
4 15 18.36 1.50 -0.45 -1.26
5 17 ∞ 0.80 0.26 -0.26

L1 1st group L2 2nd group L3 3rd group
2a 2a group
2b 2b group SP Aperture
G Glass block IP Image plane d d line g g line S Sagittal image plane M Meridional image plane

Claims (11)

In order from the object side, it has at least two lens groups of a first lens group having a negative refractive power and a second lens group having a positive refractive power,
Having a first F number determination means and a second F number determination means;
A zoom lens satisfying the following conditional expression, where S12 is a distance between the first F-number determining means and the second F-number determining means and f2 is a focal length of the second lens group.
0.3 <S12 / f2 <0.9 (1) The first F number determining means is used as means for determining the F number at the wide-angle end, and the second F number determining means is used as means for determining the F number at the telephoto end,
The distance from the most object side of the main zoom group to the first F number determination means is Ls1, the distance from the most object side of the main zoom group to the second F number determination means is Ls2, and the distance is on the image side. 2. The zoom lens according to claim 1, wherein the following conditional expression is satisfied when the position is positive: 2.
-1.0 <Ls1 / Ls2 <0 (2) 2. The following conditional expression is satisfied, where Ds1 is the opening diameter of the first F-number determining means at the wide-angle end, and Ds2 is the opening diameter Ds2 of the second F-number determining means at the telephoto end. Alternatively, the zoom lens according to claim 2.
1.0 ≦ Ds1 / Ds2 <1.5 (3) The second F-number determining means has an aperture diameter of the second F-number determining means at the intermediate focal length from the wide angle end to the telephoto end as Ds2mid, and an aperture diameter of the second F-number determining means at the telephoto end as Ds2. 4. The zoom lens according to claim 1, wherein at least one intermediate focal length satisfies the following conditional expression: 5.
0.6 <Ds2mid / Ds2 ≦ 1.0 (4) 5. The zoom lens according to claim 1, wherein the following conditional expression is satisfied when a focal length of the second lens group is f <b> 2.
0.5 <f2 / √ (fwxfT) <2.0 (5) 6. The zoom lens according to claim 1, wherein the following conditional expression is satisfied when a focal length of the first lens unit is f <b> 1.
1.8 <| f1 / fw | <3.0 (6) 7. The first lens group according to claim 1, wherein the first lens group has at least one positive lens, and satisfies the following conditional expression when the average value of the refractive index of the first lens group is Nd1. The zoom lens according to any one of the items.
Nd1> 1.80 (7) During zooming from the wide-angle end to the telephoto end, the first lens group moves along a locus convex toward the image side, the second lens group moves monotonously to the object side, and the third lens group moves toward the image side. The zoom lens according to any one of claims 1 to 7, wherein 9. The zoom lens according to claim 1, wherein the negative lens in the first lens group has an aspheric surface on the object side and the image side. 10. 10. The zoom lens according to claim 1, wherein focusing is performed from an object at infinity to an object at a short distance by moving the third lens group toward the object side. 11. An optical apparatus comprising the zoom lens according to any one of claims 1 to 10.