JP6021429B2 - Zoom lens, single focus lens, and optical apparatus having the same - Google Patents

Description

  The present invention is suitable for an optical system such as an imaging optical system used for a digital camera, a video camera, a silver salt film camera, a TV camera, or a projection optical system used for a projector.

  In recent years, image quality has been improved in projection optical systems such as digital cameras and image pickup optical systems and liquid crystal projectors. In response to this, the pixel pitch of image sensors such as CCDs and liquid crystal panels is reduced. On the other hand, in an imaging optical system having a single focal length and an optical system such as a zoom lens used for these, a wide angle of view is desired so that a wide range of imaging and a wide range of projection can be performed.

  Generally, when the optical system has a wide angle of view, the height of the paraxial ray of the pupil increases, so that distortion and color misregistration increase. At this time, in order to prevent the color from being seen in the adjacent pixels, the color misregistration must be 0.5 pixels or less. Therefore, in order to obtain an optical system with a wide angle of view, it is desired to reduce the lateral chromatic aberration that causes the color shift. Particularly in recent years, it has been demanded that chromatic aberration is corrected more favorably due to the influence of high definition of image quality.

  Conventionally, as an achromatic method (chromatic aberration correction method) of an optical system, it is known to use a material having relatively high dispersion and large anomalous dispersion for the optical system (Patent Documents 1 and 2). In Patent Document 1, chromatic aberration is corrected using a lens made of a material having high dispersion and strong anomalous dispersion in the first lens group on the object side. In Patent Document 2, chromatic aberration is corrected by using a low-dispersion material in addition to the material having the above characteristics in the first lens group.

JP 2008-158159 A JP 2004-020765 A

  In general, the refractive index of an optical material becomes higher as the wavelength is shorter in the visible region. For this reason, in correcting the lateral chromatic aberration, it is important to suppress the color shift of the g line with respect to the d line. As a lens configuration suitable for a wide-angle lens, a single focus lens includes a retrofocus type optical system, and a zoom lens includes a negative lead type optical system. In these optical systems, lens groups having negative and positive refractive powers are arranged on the enlargement side (enlargement conjugate side, object side) and reduction side (reduction conjugate side, image side), respectively, from the stop.

The retrofocus type has such a property that the back focus is longer than the focal length of the entire system due to such an arrangement. That is, the distance between the lens arranged closest to the reduction side and the reduction side focal point is larger than the focal length of the entire system. Moreover, the following property is mentioned as a feature of a retrofocus type. And h _m height from the optical axis of the marginal ray in the axial light beam. In the retrofocus type, | h _m | on the most enlargement side of the optical system is smaller than the maximum value of | h _m | on the reduction side of the entrance pupil of the optical system.

  In a retrofocus type or negative lead type optical system, the lateral chromatic aberration of g-line occurs on the over side by arranging the refractive power as described above. Furthermore, since the chromatic aberration of magnification increases as the height of the pupil paraxial ray increases, the chromatic aberration of magnification of the g-line is further bent toward the over side as the image height increases. This can be corrected by using an anomalous partially dispersive material, and the effect depends on the height of the pupil paraxial ray and the refractive power of the lens.

  For example, by using a material with a partial dispersion ratio larger than the standard for the negative lens on the enlargement side from the stop, the lateral chromatic aberration of g-line can be bent and reduced in the under direction. The same effect can be obtained by using a material having a partial dispersion ratio smaller than that of the standard for the positive lens. Since the sign of the pupil paraxial ray height changes on the reduction side from the stop, the partial dispersion ratio characteristics of the applied material may be reversed. Furthermore, the higher the dispersion of the applied material and the greater the refractive power of the lens, the greater the effect of correcting the lateral chromatic aberration of g-line.

  Hereinafter, the lateral chromatic aberration of the F line with respect to the C line is described as primary chromatic aberration, and the lateral chromatic aberration of the g line with respect to the F line is described as secondary chromatic aberration. When both the primary and secondary achromatization are performed satisfactorily, good color misregistration correction is realized.

  In the aforementioned Patent Document 1, the chromatic aberration of magnification of the g-line is corrected by using a material with very high dispersion and large anomalous dispersion for the negative lens of the first lens group. In order to maintain the primary achromatic balance of the first lens group, the positive lens in the first lens group is also made of a material having a high dispersion and a partial dispersion ratio larger than the standard. When the pixel pitch is reduced and the angle of view is further increased due to high definition, it is necessary to further reduce the lateral chromatic aberration.

  In Patent Document 2, a relatively low dispersion material and a high dispersion material having a large anomalous dispersion are used for the negative lens of the first lens group. This balances the primary chromatic aberration in the first lens group without using a material that deteriorates the secondary chromatic aberration for the positive lens in the first lens group.

  In general, since the correction amount of lateral chromatic aberration is the sum of the effects of each lens, a sufficient correction effect cannot be obtained unless the total correction amount is taken into consideration. If the anomalous dispersion of the low dispersion material used for the first lens group is very weak, the secondary achromatic effect is reduced. In Patent Document 2, since a high dispersion material having a partial dispersion ratio larger than the standard is used for the positive lens having a large refractive power in the second lens group, secondary chromatic aberration tends to remain.

  SUMMARY OF THE INVENTION An object of the present invention is to obtain a zoom lens and a single focus lens having a wide angle of view that can appropriately correct lateral chromatic aberration and cope with high definition.

  In addition, the present invention uses a lens made of an optimum material for the first lens group constituting the zoom lens and the single focus lens, and corrects the chromatic aberration of magnification by appropriately defining the correction amount of chromatic aberration by the lens on the enlargement side from the stop. An object of the present invention is to provide a zoom lens and a single focus lens which are well performed.

The zoom lens according to the present invention includes a first lens group having a negative refractive power disposed on the most enlargement side, and a stop disposed on the reduction side with respect to the first lens group. Having a plurality of negative lenses,
The maximum and minimum Abbe numbers of the negative lens materials included in the first lens group are ν _{n, max} , ν _{n, min} , respectively _, the focal length of the entire system at the wide angle end is f _W , and the enlargement side from the stop The number of lenses existing in the lens is ib, and among the ib lenses, in order from the magnification side, the refractive power of the i-th lens is φ _i , and the Abbe number and partial dispersion ratio of the material of the i-th lens are The partial dispersion ratio difference Δθ _i is Δθ _i = θ _{gF, i} − (0.6438−0.001682ν _i ), respectively, with ν _i and θ _{gF, i.}
And when
3.3 <ν _{n, max} / ν _{n, min} <6.5
It is characterized by satisfying.
In addition, the zoom lens of the present invention includes a first lens group having a negative refractive power that is disposed closest to the enlargement side, and a diaphragm that is disposed closer to the reduction side than the first lens group. The lens group has a plurality of negative lenses, has a plurality of positive lenses on the reduction side from the stop,
The maximum and minimum Abbe numbers of the negative lens material included in the first lens group are ν _{n, max} and ν _{n, min} , respectively, and the maximum Abbe number of the material of the positive lens located on the reduction side from the stop. Ν _{p, max} and ν _{p, min} , respectively _, the focal length of the entire system at the wide-angle end is f _W , the number of lenses existing on the magnification side from the stop is ib, and among the ib lenses In order from the enlargement side, the refractive power of the i-th lens is φ _i , the Abbe number and partial dispersion ratio of the i-th lens material are ν _i and θ _{gF, i} , respectively _, and the partial dispersion ratio difference Δθ _i is
Δθ _i = θ _{gF, i} − (0.6438−0.001682ν _i )
And when
3.3 <ν _{n, max} / ν _{n, min} <6.5
2.5 <ν _{p, max} / ν _{p, min} <6.5
It is characterized by satisfying.
In addition, the zoom lens of the present invention includes, in order from the enlargement side to the reduction side, a first lens group having a negative refractive power, a second lens group having a positive refractive power, a third lens group having a negative refractive power, and a positive lens group. A fourth lens unit having a refractive power, and an interval between adjacent lens units is changed during zooming, and further includes a stop disposed on the reduction side of the first lens unit. Have a negative lens,
The maximum and minimum Abbe numbers of the negative lens material included in the first lens group are ν _{n, max} and ν _{n, min} , respectively _, the focal length of the entire system at the wide angle end is f _W , and the enlargement side from the stop The number of lenses existing in the lens is ib, and among the ib lenses, in order from the magnification side, the refractive power of the i-th lens is φ _i , and the Abbe number and partial dispersion ratio of the material of the i-th lens are _Let ν _i , θ _{gF, i} be the partial dispersion ratio difference Δθ _i , respectively.
Δθ _i = θ _{gF, i} − (0.6438−0.001682ν _i )
And when
3.3 <ν _{n, max} / ν _{n, min} <6.5
Meet
It is characterized by that.

In addition, a single focus lens according to another aspect of the present invention is a single focus lens in which the distance between the lens arranged closest to the reduction side and the reduction side focus is larger than the focal length of the entire system, Have
  The lens group on the enlargement side than the stop is a front group, the front group has a plurality of negative lenses,
  The maximum and minimum Abbe numbers of the negative lens materials included in the front group _{n, max} And ν _{n, min} , The focal length of the entire system is f, the number of lenses included in the front group is ib, and the refractive power of the i-th lens is φ in order from the magnification side of the ib lenses. _i , The Abbe number and the partial dispersion ratio of the i-th lens material, respectively, _i , Θ _{gF, i} And partial dispersion ratio difference Δθ _i The
Δθ _i = Θ _{gF, i} − (0.6438−0.001682ν _i )
And when
3.3 <ν _{n, max} / Ν _{n, min} <6.5
It is characterized by satisfying.
In addition, a single focus lens according to another aspect of the present invention is a single focus lens in which the distance between the lens arranged closest to the reduction side and the reduction side focus is larger than the focal length of the entire system, Have
  The lens group on the enlargement side than the stop is a front group, the front group has a plurality of negative lenses,
  The maximum and minimum Abbe numbers of the negative lens materials included in the front group _{n, max} , Ν _{n, min} , The focal length of the entire system is f, the number of lenses included in the front group is ib, and the refractive power of the i-th lens is φ in order from the magnification side of the ib lenses. _i , The Abbe number and the partial dispersion ratio of the i-th lens material, respectively, _i , Θ _{gF, i} And partial dispersion ratio difference Δθ _i The
Δθ _i = Θ _{gF, i} − (0.6438−0.001682ν _i )
And when
3.3 <ν _{n, max} / Ν _{n, min} <6.5
The filling,
  Among the plurality of negative lenses, the Abbe number of the lens material is the maximum value ν _{n, max} And the minimum value ν _{n, min} The two negative lenses taking the position are arranged continuously from the enlargement side to the reduction side on the reduction side of the first lens arranged on the most enlargement side, and move along the same locus as the first lens during focusing. It is characterized by that.
In addition, a single focus lens according to another aspect of the present invention is a single focus lens in which the distance between the lens arranged closest to the reduction side and the reduction side focus is larger than the focal length of the entire system, Have
  The lens group on the enlargement side than the stop is a front group, the front group has a plurality of negative lenses,
  A plurality of positive lenses on the reduction side of the diaphragm;
  The maximum and minimum Abbe numbers of the negative lens materials included in the front group _{n, max} , Ν _{n, min} , The maximum value and the minimum value of the Abbe number of the material of the positive lens located on the reduction side from the stop _{p, max} , Ν _{p, min} , The focal length of the entire system is f, the number of lenses included in the front group is ib, and the refractive power of the i-th lens is φ in order from the magnification side of the ib lenses. _i , The Abbe number and the partial dispersion ratio of the i-th lens material, respectively, _i , Θ _{gF, i} And partial dispersion ratio difference Δθ _i The
Δθ _i = Θ _{gF, i} − (0.6438−0.001682ν _i )
And when
3.3 <ν _{n, max} / Ν _{n, min} <6.5
2.5 <ν _{p, max} / Ν _{p, min} <6.5
It is characterized by satisfying.

According to the present invention, it is possible to obtain a zoom lens and a single focus lens having a wide angle of view that can appropriately correct lateral chromatic aberration and cope with high definition.

Cross-sectional view of a lens according to Example 1 of the present invention Various aberration diagrams in Example 1 of the present invention Lens sectional drawing of Example 2 of the present invention (A), (B) Various aberration diagrams in Example 2 of the present invention Lens sectional view of Example 3 of the present invention (A), (B) Various aberration diagrams in Example 3 of the present invention Lens sectional view of Example 4 of the present invention (A), (B) Various aberration diagrams in Example 4 of the present invention Lens sectional drawing of Example 5 of the present invention (A), (B) Various aberration diagrams in Example 5 of the present invention Schematic diagram of essential parts of the optical apparatus of the present invention Schematic diagram of essential parts of the optical apparatus of the present invention Conceptual diagram showing change in chromatic aberration of magnification of g-line by conditional expression (2) (A), (B) Chromatic aberration diagram at the wide-angle end of a conventional projection optical system and the chromatic aberration diagram at the wide-angle end of Example 4 of the present invention Lens sectional view of Embodiment 6 of the present invention Various aberration diagrams in Example 6 of the present invention

  A zoom lens, a single focus lens and an image pickup apparatus having the same according to the present invention will be described. The present invention is an optical system such as a single focus lens and a zoom lens. Here, the diaphragm is not limited to an aperture diaphragm that controls the aperture diameter, but includes a diaphragm with a fixed aperture diameter or a diaphragm that is specified by a lens effective diameter. For example, the edge part of a lens is also included.

  FIG. 1 is a lens cross-sectional view of Embodiment 1 of the present invention. FIG. 2 is an aberration diagram of Example 1 of the present invention. FIG. 3 is a lens cross-sectional view at the wide-angle end (short focal length end) of Embodiment 2 of the present invention. FIGS. 4A and 4B are aberration diagrams at the wide-angle end and the telephoto end (long focal length end) according to the second embodiment of the present invention. FIG. 5 is a lens cross-sectional view at the wide angle end according to Embodiment 3 of the present invention. FIGS. 6A and 6B are aberration diagrams at the wide-angle end and the telephoto end according to the third embodiment of the present invention.

  FIG. 7 is a lens cross-sectional view at the wide angle end according to Embodiment 4 of the present invention. FIGS. 8A and 8B are aberration diagrams at the wide-angle end and the telephoto end of Example 4 of the present invention. FIG. 9 is a lens cross-sectional view at the wide-angle end according to Embodiment 5 of the present invention. FIGS. 10A and 10B are aberration diagrams at the wide-angle end and the telephoto end of Example 5 of the present invention. 11 and 12 are schematic views of the main part of the optical apparatus of the present invention. FIG. 15 is a lens sectional view of Example 6 of the present invention. FIG. 16 is an aberration diagram of Example 6 of the present invention.

  Conventionally, in many optical systems, a material having relatively high dispersion and large anomalous dispersion has been used to correct lateral chromatic aberration. When correcting chromatic aberration of magnification, it is necessary to pay attention to the correction amount of the entire optical system that combines the correction effects of each lens.

In an optical system such as a wide-angle single-focus lens or a zoom lens according to the present invention, the Abbe number of a high dispersion material and a low dispersion material with strong anomalous dispersion used in the first lens group or the front group having negative refractive power. (Abbe number) is set appropriately. Further, the correction amount of the chromatic aberration of the lens existing between the most magnified side (magnifying conjugate side) and the aperture stop is appropriately set. In the following, for ease of explanation, a zoom lens is taken as an example. If the first lens group described below is replaced with the front group, the effects of the present invention can be obtained in the same way with a single focus lens. The single focus lens corresponds to the zoom position at the wide angle end of the zoom lens.

  According to the zoom lens of the present invention, even if a high dispersion material having a large anomalous dispersion is used for the negative lens included in the first lens group, it is not necessary to use a material that increases the lateral chromatic aberration of g-line for the positive lens. . This is because primary achromaticity can be maintained by greatly separating the difference in Abbe number between the materials of the two negative lenses in the first lens group. In addition, the chromatic aberration of magnification was corrected well as shown in FIGS. 14A and 14B by keeping the contribution to the secondary chromatic aberration of all the lenses located on the enlargement side from the aperture stop within an appropriate range. A wide-angle optical system is realized.

  FIG. 14A is a chromatic aberration diagram of magnification of a conventional projection optical system. FIG. 14B is an aberration diagram at the wide-angle end of the zoom lens according to the fourth embodiment of the present invention.

  Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings. In each lens sectional view, Li is the i-th lens group. LF is the front group and LR is the rear group. G1 is a lens closest to the magnification conjugate side. SP is a diaphragm with a fixed aperture diameter or variable aperture diameter, GB is a glass block such as a filter or a color separation prism, and IP is a conjugate plane (image plane in the imaging optical system) on the reduction conjugate side. The arrows indicate the movement trajectory of each lens unit during zooming from the wide-angle end to the telephoto end or the moving direction during focusing from an infinitely distant object to a close object.

In the zoom lens of each embodiment, the first lens unit L1 includes a plurality of negative lenses, and the maximum value ν _{n, max} and the minimum value ν _n of the Abbe number of the material of the negative lens included in the first lens unit L1 _{. Let} it be _min . The focal length at the wide angle end is f _W , and the number of lenses existing on the magnification conjugate side of the stop SP or the lens group including the stop SP is ib. In order from the enlargement conjugate side to the reduction conjugate side, the refractive power of the i-th lens among the ib lenses is φ _i , and the Abbe number and partial dispersion ratio of the material are v _i and θ _{gF, i} , respectively. Then, the partial dispersion ratio difference Δθ _i (abnormal partial dispersion ratio) is changed to Δθ _i = θ _{gF, i} − (0.6438−0.001682ν _i ).
far. At this time,
3.3 <ν _{n, max} / ν _{n, min} <6.5 (1)

The following conditional expression is satisfied. In addition, the upper limit of conditional expression (2) uses the value of Numerical Example 4 described later,
It is good to do. In addition, the upper limit value of conditional expression (2) uses the value of Numerical Example 1 described later,
It is good to do. Hereinafter, conditional expressions (2), (2x), and (2Y) are collectively referred to as conditional expressions (2). As described above, in the retrofocus optical system, the distance between the lens arranged closest to the reduction side and the reduction side focus is larger than the focal length of the entire system. At the wide-angle end of a retrofocus type single focus lens or a negative lead type zoom lens, in many cases, lateral chromatic aberration of the g-line occurs on the over side with respect to the d-line.

  Conditional expression (2) represents the correction effect for this on the enlargement side of the stop. If the value of conditional expression (2) is negative, the lateral chromatic aberration of g-line is bent in the under direction and becomes small. On the contrary, if it is positive, it bends further in the over direction, increasing the aberration. FIG. 13 illustrates this effect.

  Conventionally, a high dispersion material having a large anomalous dispersion has been used to correct lateral chromatic aberration in an optical system with a wide angle of view. High dispersion materials generally have a positive partial dispersion ratio difference Δθ, and the value tends to increase as the dispersion increases. When this material is used on the enlargement side from the stop, secondary chromatic aberration can be corrected by applying it to the negative lens from the conditional expression (2). At this time, the effect becomes higher as the refractive power of the negative lens is stronger and the height of the paraxial ray of the pupil is higher. Therefore, in the present invention, the above material is applied to the negative lens included in the first lens group in which the height of the pupil paraxial ray is generally increased.

  However, this causes the primary achromatic balance in the first lens group to be lost. For this purpose, it is necessary to shift the material of the positive lens in the first lens group to the high dispersion side. As described above, a highly dispersed material generally has a positive partial dispersion ratio difference Δθ. Therefore, when a high dispersion material is used for the positive lens, the lateral chromatic aberration of g-line at the wide angle end is deteriorated.

  Therefore, in the present invention, a high dispersion material and a very low dispersion material are used for the negative lens so as to satisfy the conditional expression (1). As a result, the primary chromatic aberration in the first lens group is corrected in a well-balanced manner without using a high dispersion material for the positive lens.

  Conditional expression (2) is defined so that the chromatic aberration of magnification of the g-line is favorably corrected (at the wide-angle end in the case of a zoom lens) so as to correspond to a wide field angle or high definition. In the conditional expression (2), φ · Δθ / ν represents the correction amount of the chromatic aberration of the g-line of the optical system, and on the enlargement side of the stop SP, the larger this value is in the negative direction, the second-order achromatic effect. Is expensive. The value of conditional expression (2), which is the sum of the effects of each lens, represents the final correction amount of lateral chromatic aberration.

  Next, the derivation of conditional expression (2) will be described in detail. The magnification chromatic aberration coefficient of the entire optical system is described by the following expressions (a1) and (a2).

Here, T _FC is a magnification chromatic aberration coefficient for the F line and C line, and T _gF is a magnification chromatic aberration coefficient for the g line and F line. i _max is the total number of lenses constituting the optical system. h _i is a height from the optical axis of the i-th object paraxial ray incident on the lens,

Is the height from the optical axis of the paraxial ray of the pupil incident on the i-th lens. An object paraxial ray is a paraxial ray that is emitted from an object point on the optical axis and enters the optical system. A pupil paraxial ray is emitted from an off-axis object point and is the center of the entrance pupil of the optical system. Represents a paraxial ray incident toward. Now, consider a case where the material of the j-th lens from the magnification side is changed. The magnification chromatic aberration coefficient regarding the F line and the C line at this time is expressed by the following expression (a3), and the magnification chromatic aberration coefficient regarding the g line and the F line is expressed as expression (a4).

Where Φ _j , Ν _j , Θ _{gF, j} , H _j ,

Are the refractive power, Abbe number, partial dispersion ratio, height of incidence of object paraxial rays, and height of incidence of pupil paraxial rays, respectively. If the expressions (a3) and (a4) are closer to 0 than the values of the expressions (a1) and (a2), respectively, the chromatic aberration of magnification is corrected by changing the material. Assuming that the primary achromatization is sufficiently performed, the following equation (a5) is approximately established in the equation (a3).

By substituting equation (a5) into equation (a4), the following equation (a6) is obtained.

The second term of the formula (a6) represents the secondary achromatic effect due to the change of the material of the jth lens. From the second term of the formula (a6), it is possible to correct for the chromatic aberration of magnification of the g-line by using a material having a high dispersion and a partial dispersion ratio that is significantly different from the material before the change in the lens having a large incident height and refractive power. It turns out that an effect increases. With anomalous dispersion material having a _{large, | Θ gF, j -θ gF} , j | for the likely value increases, seen to be effective in secondary achromatic. When the secondary chromatic aberration is on the over side, the secondary chromatic aberration can be corrected if the second term of the formula (a6) has a negative value.

The sign of the sign is reversed depending on whether the aperture is on the enlargement side or the reduction side. Therefore, on the enlargement side from the stop, by using the anomalous dispersive material having high dispersion and a large Δθ as described above for the lens having negative refractive power, the second term of the formula (a6) is set to a large negative value. it can. Up to this point, the secondary achromatic effect when the material is changed for one lens has been described. When the materials of the plurality of lenses are changed, the second term of the formula (a6) is obtained for each lens, and the sum thereof may be taken. From the above, conditional expression (2) is obtained as a condition that the secondary achromatic effect is sufficiently performed on the enlargement side from the stop.

  In general, a high dispersion or low dispersion material has a positive and large partial dispersion ratio Δθ. Therefore, the secondary chromatic aberration can be largely corrected by using a negative lens having a large refractive power on the enlargement side of the stop SP. Further, Δθ / ν generally increases as the dispersion becomes very high or low. Therefore, the correction amount of the secondary chromatic aberration can be increased by separating the dispersibility difference between the materials of the two negative lenses of the first lens unit L1 so as to satisfy the conditional expression (1).

  However, as described above, the final lateral chromatic aberration must be considered as a combination of the effects of each lens. Therefore, it is necessary to consider the conditional expression (2) that is the sum of the correction effects of each lens, not a single lens.

  Therefore, the material of the negative lens in the first lens unit L1 is selected so as to satisfy the conditional expression (1), and the correction amount of chromatic aberration on the enlargement side from the stop SP is within the range of the conditional expression (2). As a result, it is easy to efficiently and satisfactorily delete the primary and secondary colors even in an optical system having a very wide angle of view.

Conversely if it exceeds the upper limit or lower limit of condition (1), a partial dispersion ratio difference Δθ of the positive lens material or become large heard high dispersion material, the partial dispersion ratio difference Δθ of the material of the negative lens becomes small conditions The upper limit of Expression (2) cannot be satisfied. For this reason, the lateral chromatic aberration of g line remains. If the lower limit of conditional expression (2) is exceeded, correction will be excessive, and lateral chromatic aberration will appear larger on the opposite under side than before correction, as shown in FIG. For this reason, the range defined by conditional expression (2) is preferable.

By satisfying conditional expressions (1) and (2) at the same time, primary and secondary chromatic aberration can be corrected efficiently even if a high dispersion material having a large anomalous dispersion is used for the negative lens. Highly dispersed materials generally have a large refractive index and are advantageous in terms of aberrations. Therefore, if a material is selected as in conditional expression (1), each aberration including lateral chromatic aberration can be corrected well, and an optical system with a wide angle of view corresponding to high definition can be realized. Conditional expressions (1) and (2) are more preferably set as follows.
3.35 <ν _{n, max} / ν _{n, min} <6.00 (1a)

In the single focus lens, the two negative lenses satisfying conditional expression (1) are continuously arranged from the enlargement side to the reduction side on the reduction side of the first lens arranged closest to the enlargement side, and it is desirable to move at the same locus as the first lens hand upon focusing. As described above, the secondary achromatic effect increases as the height of the pupil paraxial ray increases. By including the two negative lenses in the plurality of lenses, the negative lens is positioned on the enlargement side with respect to the stop, and the height of the pupil paraxial ray can be increased. In each embodiment, it is more preferable to satisfy one or more of the following conditions.

The refractive index at the d-line of the material of the negative lens Abbe number of the material of the lens of the negative lens in the first lens unit L1 is the minimum value [nu _{n, min} and n _d. The first lens unit L1 has at least one positive lens. The refractive power of at least one positive lens included in the first lens unit L1 is φ _P, and the Abbe number and partial dispersion ratio of the material are ν _P and θ, respectively. _The partial dispersion ratio difference Δθ _P is set as Δθ _P = θ _gFP − (0.6438−0.001682ν _P ). A plurality of positive lenses are provided on the reduction conjugate side of the stop SP , and the maximum value and the minimum value of the Abbe number of the material of the positive lens located on the reduction conjugate side of the stop SP are ν _{p, max} and ν _{p, min} , respectively. .

At this time,
1.8 < _nd <2.5 (3)
−0.0002 <f _W · φ _P · Δθ _P / ν _P <0.0000 (4)
2.5 <ν _{p, max} / ν _{p, min} <6.5 (5)
It is preferable to satisfy one or more of the following conditional expressions.

Next, the technical meaning of each conditional expression described above will be described. When the lower limit of conditional expression (3) is exceeded, aberrations such as distortion increase, and when the upper limit is exceeded, correction of the Petzval sum becomes difficult, and as a result, it becomes difficult to obtain good optical performance. Conditional expression (3) is more preferably set as follows.
_{1.82 <n d <2.0 ··· (} 3a)
Further, conditional expression (1) eliminates the need for the material of the positive lens in the first lens unit L1 to have so high dispersion. Therefore, by selecting a material for which the partial dispersion ratio difference Δθ is negative for the positive lens, it is possible to more effectively suppress the lateral chromatic aberration of g-line. Thereby, it is understood that the conditional expression (4) should be satisfied.

Even if the upper limit or the lower limit of conditional expression (4) is exceeded, it is difficult to correct chromatic aberration. More desirably, when the numerical range of the conditional expression (4a) is set as follows, secondary chromatic aberration is facilitated while maintaining a better optical performance.
−0.00010 <f _W · φ _P · Δθ _P / ν _P ≦ −0.00001 (4a)
So far, only the lens positioned on the enlargement side with respect to the stop SP has been described. In the present invention, the same argument holds for a lens on the reduction side with respect to the stop SP. On the reduction side of the stop SP, the height of the pupil paraxial ray is opposite to that on the enlargement side. Therefore, a material in which the partial dispersion ratio difference Δθ is positive for the positive lens and the partial dispersion ratio difference Δθ is negative for the negative lens is used. Apply it.

In this case, the maximum value Ab _p number of the positive lens located on the reduction side from the stop SP, v _{p, max} , and the minimum Abbe number of the positive lens located on the reduction side from the stop as v _{p, min} , the conditional expression (5 It is good to satisfy. If the lower limit of the conditional expression (5) is not satisfied, the negative lens becomes a material having a large positive partial dispersion ratio difference Δθ, or the correction effect of the secondary chromatic aberration is reduced, and the lateral chromatic aberration remains. On the other hand, if the upper limit is exceeded, the material is very limited, making it difficult to obtain good optical performance.

Desirably, if the numerical range of conditional expression (5) is set as follows, it becomes easier to further suppress the occurrence of lateral chromatic aberration.
2.7 <ν _{p, max} / ν _{p, min} <6.5 (5a)
Next, the lens configurations of the zoom lens and the single focus lens of each embodiment will be described.
[Example 1]
A first embodiment of the present invention shown in FIG. 1 will be described. The present embodiment is a wide-angle single-focus lens mounted on a single-lens reflex camera or the like. The single focus lens in FIG. 1 includes, in order from the object side to the image side, a front group LF having a positive refractive power and a rear group LR having a positive refractive power. IP is the image plane. The entire optical system moves on the optical axis and performs focusing.

  A high dispersion material such as ν (Abbe number) = 18.90 and Δθ (partial dispersion ratio difference) = 0.03749 having a large anomalous dispersion in the negative lens of the front lens group LF, ν = 95.00, Δθ = 0.04999 The chromatic aberration of magnification is corrected using such a low dispersion material. The positive lens in the front lens group LF uses the materials such as ν = 39.70 and Δθ = −0.00332 to efficiently perform secondary achromatization. In the first embodiment, ib = 9.

[Example 2]
A second embodiment of the present invention shown in FIG. 3 will be described. This embodiment is a zoom lens with a wide angle of view mounted on a single-lens reflex camera or the like. The zoom lens of FIG. 3 includes, in order from the object side to the image side, a first lens unit L1 having a negative refractive power, a second lens unit L2 having a positive refractive power, a third lens unit L3 having a negative refractive power, The lens unit includes a fourth lens unit L4 having a positive refractive power. IP is the image plane. During zooming from the wide-angle end to the telephoto end, all of the first to fourth lens groups move independently as indicated by arrows. That is, the distance between adjacent lens groups changes during zooming.

  By making the most image-side surface of the fourth lens unit L4 an aspherical surface, variation in aberrations during zooming is suppressed. Further, by making the most object side surface of the first lens unit L1 an aspherical shape, distortion is corrected well while having a wide angle of view. The negative lens of the first lens unit L1 is used in combination with a high dispersion material such as ν = 22.76 and Δθ = 0.02518 having a large anomalous dispersion and a low dispersion material such as ν = 76.98 and Δθ = 0.02578. The lateral chromatic aberration is corrected. For the positive lens in the first lens unit L1, secondary achromaticity is performed using materials such as ν = 37.20 and Δθ = −0.00363. In the second embodiment, ib = 7.

[Example 3]
A third embodiment of the present invention shown in FIG. 5 will be described. This embodiment is a zoom lens with a wide angle of view mounted on a single-lens reflex camera or the like.

  The zoom type is the same as that of the second embodiment in FIG. A high dispersion material such as ν = 22.76 and Δθ = 0.02518 and a low dispersion material such as ν = 81.54 and Δθ = 0.03085 are used in combination for the negative lens of the first lens unit L1. The positive lens of the first lens unit L1 uses materials such as ν = 37.20 and Δθ = −0.00363. Others are the same as in the second embodiment. In the third embodiment, ib = 7.

[Example 4]
A fourth embodiment of the present invention shown in FIG. 7 will be described. This embodiment is a wide-angle zoom lens for projection mounted on a liquid crystal projector or the like. In order from the magnification conjugate side (enlargement side, screen side) to the reduction conjugate side (reduction side, liquid crystal panel side), a first lens unit L1 having a negative refractive power, a second lens unit L2 having a positive refractive power, a positive The lens unit includes a third lens unit L3 having a refractive power and a fourth lens unit L4 having a positive refractive power. GB denotes a glass block such as a color separation prism, and IP denotes a display surface of the liquid crystal display element. At the time of zooming from the wide-angle end to the telephoto end, at least the second and third lens units L2 and L3 move independently as indicated by arrows.

  The fourth lens unit L4 is fixed during zooming so that the reduction conjugate side is telecentric with respect to the entire zoom range. The first lens unit L1 is also fixed because it is heavy and has a large load to be used for focusing. Focusing is performed by the second lens unit L2 including one lens unit.

  In this embodiment, the negative lens of the first lens unit L1 has a low dispersion material such as ν = 95.00 and Δθ = 0.04999 which has a large anomalous dispersion, and a high dispersion material such as ν = 18.90 and Δθ = 0.03749. By using this, the lateral chromatic aberration is corrected well. Further, by using a material such as ν = 37.20 and Δθ = −0.00363 for the positive lens of the first lens unit L1, secondary achromaticity is efficiently performed. In Example 4, ib = 10.

[Example 5]
A fifth embodiment of the present invention shown in FIG. 9 will be described. This embodiment is a wide-angle zoom lens for projection mounted on a liquid crystal projector or the like. In order from the magnification conjugate side to the reduction conjugate side, the lens unit includes the following lens groups. The first lens unit L1 having negative refractive power, the second lens unit L2 having positive refractive power, the third lens unit L3 having positive refractive power, the fourth lens unit L4 having positive refractive power, the positive The lens unit includes a fifth lens unit L5 having a refractive power and a sixth lens unit having a positive refractive power.

  During zooming from the wide-angle end to the telephoto end, all of the second to fifth lens groups move independently as indicated by arrows. During zooming, the first lens unit L1 and the sixth lens unit L6 are fixed. Focusing is performed by moving the second lens unit L2. A low dispersion material such as ν = 81.54 and Δθ = 0.03085 and a high dispersion material such as ν = 18.90 and Δθ = 0.03749 are used in combination for the negative lens of the first lens unit L1. In the fifth embodiment, ib = 10.

[Example 6]
A sixth embodiment of the present invention shown in FIG. 15 will be described. The present embodiment is a wide-angle single-focus lens mounted on a single-lens reflex camera or the like. The single focus lens in FIG. 15 includes, in order from the object side to the image side, a front group LF having a positive refractive power and a rear group LR having a positive refractive power. IP is the image plane. The front group LF includes a first partial group LF1 that does not move during focusing, and a second partial group LF2 that moves in the optical axis direction to perform focusing.

  A high dispersion material such as ν (Abbe number) = 18.90 and Δθ (partial dispersion ratio difference) = 0.03749 having large anomalous dispersion on the negative lens of the first subgroup LF1 of the front group LF, and ν = 95.00 , Chromatic aberration of magnification is corrected using a low dispersion material such as Δθ = 0.04999. The positive lens of the front lens group LF uses a material such as ν = 35.25 and Δθ = −0.00241 to efficiently perform secondary achromatization. In Example 6, ib = 9.

  As mentioned above, although preferable embodiment of this invention was described, this invention is not limited to these embodiment, A various deformation | transformation and change are possible within the range of the summary.

Next, numerical examples in the respective embodiments are shown below. i indicates the order of the surfaces from the object side (enlargement side), r _i is the radius of curvature of the i-th surface, and d _i is the lens thickness or air spacing between the i-th surface and the (i + 1) -th surface. nd _i and νd _i represent the refractive index and Abbe number for the d-line, respectively. θgF represents a partial dispersion ratio. In Numerical Examples 4 and 5, four surfaces arranged on the most reduction side are surfaces constituting the glass block GB, and are planes. The back focus BF is a distance in terms of air from the final lens surface to the image plane. Half angle of view is expressed in degrees.

k, A ₄ , A ₆ , A ₈ , A ₁₀ and A ₁₂ are aspheric coefficients. The aspherical shape is defined by the following expression when the displacement in the optical axis direction at the height h from the optical axis is x with respect to the surface vertex.
x = (h ² / r) / [1 + {1− (1 + k) (h / r) ² } ^1/2 ] + A ₄ h ⁴ + A ₆ h ⁶ + A ₈ h ⁸ + A ₁₀ h ¹⁰ + A ₁₂ h ¹²
Where r is the paraxial radius of curvature. The display of the E-y is the meaning of 10 ^-y. Table 1 shows the values of the conditional expressions in the numerical examples.

Numerical example 1
Unit mm

Surface data surface number rd nd νd Effective diameter θgF
1 2.958 0.14 1.59282 68.6 4.58 0.5441
2 1.875 0.43 3.57
3 2.254 0.14 1.49700 81.5 3.56 0.5375
4 1.403 0.65 2.75
5 2.247 0.14 1.43875 94.9 2.75 0.5340
6 * 0.730 0.84 2.20
7 9.530 0.35 1.92286 18.9 2.12 0.6495
8 2.084 0.08 1.86
9 3.211 0.35 1.91082 35.3 1.86 0.5821
10 13.537 0.39 1.77
11 2.045 0.14 1.80 100 35.0 1.50 0.5864
12 0.994 0.48 1.72047 34.7 1.33 0.5834
13 -2.547 0.01 1.25
14 -2.324 0.35 1.61800 63.3 1.24 0.5441
15 0.776 0.35 1.65412 39.7 0.99 0.5737
16 -5.261 0.51 0.93
17 (Aperture) ∞ 0.04 0.86
18 11.774 0.17 1.83400 37.2 0.85
19 1.174 0.01 0.83
20 1.181 0.39 1.49700 81.5 0.83
21 -0.598 0.14 1.83400 37.2 0.84
22 -5.053 0.01 0.96
23 5.408 0.36 1.49700 81.5 1.03
24 -0.938 0.01 1.14
25 * -2.655 0.19 1.71736 29.5 1.22
26 -1.698 2.82 1.31
Image plane ∞

Aspheric data 6th surface
K = -7.05181e-001 A 4 = -4.04170e-002 A 6 = -5.83979e-002 A 8 = 6.88039e-003 A10 =
-3.88641e-002

25th page
K = 5.36176e + 000 A 4 = -2.93222e-002 A 6 = 1.84527e-002 A 8 = -5.33384e-002 A10 =
-2.69443e-002

Various data Zoom ratio 1.00

Focal length 1.00
F number 2.90
Half angle of view 56.66
Image height 1.52
Total lens length 9.51
BF 2.82

Entrance pupil position 2.01
Exit pupil position -1.65
Front principal point position 2.79
Rear principal point position 1.82

Single lens Data lens Start surface Focal length
1 1 -9.08
2 3 -7.92
3 5 -2.54
4 7 -2.96
5 9 4.55
6 11 -2.57
7 12 1.05
8 14 -0.90
9 15 1.06
10 18 -1.57
11 20 0.86
12 21 -0.83
13 23 1.64
14 25 6.06

Numerical example 2
Unit mm

Surface data surface number rd nd νd Effective diameter θgF
1 * -40.420 0.11 1.80809 22.8 2.74 0.6307
2 1.212 0.67 2.00
3 -3.556 0.11 1.52855 77.0 2.00 0.5401
4 1.955 0.01 1.51640 52.2 1.88 0.5560
5 * 2.322 0.01 1.87
6 1.871 0.35 1.83400 37.2 1.88 0.5776
7 25.392 (variable) 1.83
8 4.224 0.12 1.80 100 35.0 1.09 0.5864
9 1.010 0.43 1.72047 34.7 1.04 0.5834
10 117.659 0.54 1.08
11 2.807 0.21 1.74950 35.3 1.25 0.5818
12 -11.718 (variable) 1.25
13 (Aperture) ∞ 0.06 1.14
14 -2.777 0.11 1.69680 55.5 1.14
15 17.122 0.04 1.15
16 -5.146 0.11 1.83400 37.2 1.15
17 1.338 0.27 1.84666 23.8 1.21
18 -10.317 (variable) 1.23
19 1.506 0.51 1.59240 68.3 1.28
20 -1.180 0.11 1.83400 37.2 1.24
21 -1.906 0.01 1.26
22 9.215 0.11 1.84666 23.8 1.26
23 1.891 0.31 1.49700 81.5 1.24
24 -2.350 0.01 1.25
25 -2.297 0.11 1.84666 23.8 1.25
26 * -13.619 (variable) 1.28
Image plane ∞

Aspheric data 1st surface
K = -6.16680e + 004 A 4 = 8.76671e-002 A 6 = -4.26370e-002 A 8 = 1.81127e-002 A10 =
-4.89163e-003 A12 = 5.94333e-004

5th page
K = 3.39137e + 000 A 4 = 4.10907e-002 A 6 = -3.32966e-002 A 8 = -8.64643e-002 A10 =
1.12993e-001 A12 = -6.56823e-002

26th page
K = -1.40230e + 003 A 4 = 4.70464e-002 A 6 = 1.58162e-001 A 8 = -3.24609e-002 A10 =
-1.11240e-001 A12 = 2.23772e-001

Various data Zoom ratio 2.06
Wide angle Medium Telephoto focal length 1.00 1.45 2.06
F number 2.59 2.96 3.50
Half angle of view 51.25 41.72 32.84
Image height 1.25 1.30 1.33
Total lens length 8.79 8.40 8.58
BF 2.42 2.86 3.50

d 7 1.30 0.53 0.07
d12 0.01 0.34 0.67
d18 0.73 0.35 0.02
d26 2.42 2.86 3.50

Entrance pupil position 1.10 1.07 1.10
Exit pupil position -2.93 -1.78 -1.19
Front principal point position 1.91 2.07 2.26
Rear principal point position 1.42 1.41 1.44

Zoom lens group data group Start surface Focal length Lens configuration length Front principal point position Rear principal point position
1 1 -1.61 1.26 -0.00 -1.05
2 8 2.49 1.30 0.71 -0.35
3 13 -2.80 0.59 0.04 -0.34
4 19 2.21 1.17 -0.01 -0.71

Single lens Data lens Start surface Focal length
1 1 -1.45
2 3 -2.37
3 4 23.77
4 6 2.41
5 8 -1.68
6 9 1.41
7 11 3.04
8 14 -3.42
9 16 -1.26
10 17 1.41
11 19 1.20
12 20 -3.99
13 22 -2.83
14 23 2.16
15 25 -3.28

Numerical example 3
Unit mm

Surface data surface number rd nd νd Effective diameter θgF
1 * -40.371 0.11 1.80809 22.8 2.74 0.6307
2 1.212 0.69 2.00
3 -3.152 0.11 1.49700 81.5 2.00 0.5375
4 2.020 0.01 1.51640 52.2 1.89 0.5560
5 * 2.375 0.01 1.89
6 1.968 0.34 1.83400 37.2 1.91 0.5776
7 37.509 (variable) 1.88
8 3.938 0.11 1.80 100 35.0 1.70 0.5864
9 1.101 0.46 1.72047 34.7 1.58 0.5834
10 -18.666 0.49 1.56
11 2.863 0.22 1.65412 39.7 1.41 0.5737
12 -10.518 (variable) 1.38
13 (Aperture) ∞ 0.05 0.94
14 -2.975 0.11 1.69680 55.5 1.09
15 12.902 0.05 1.10
16 -3.663 0.11 1.83400 37.2 1.10
17 1.287 0.27 1.84666 23.9 1.17
18 -7.468 (variable) 1.21
19 1.421 0.54 1.49700 81.5 1.42
20 -1.191 0.11 1.80440 39.6 1.42
21 -1.741 0.01 1.46
22 9.355 0.11 1.84666 23.8 1.40
23 1.593 0.30 1.69680 55.5 1.34
24 -4.622 0.02 1.33
25 -3.521 0.11 1.84666 23.8 1.33
26 * -1282.057 (variable) 1.33
Image plane ∞

Aspheric data 1st surface
K = -3.71542e + 004 A 4 = 8.41381e-002 A 6 = -4.18984e-002 A 8 = 1.93219e-002 A10 =
-5.57516e-003 A12 = 7.04170e-004

5th page
K = 3.46332e + 000 A 4 = 3.72343e-002 A 6 = -4.23426e-002 A 8 = -5.79351e-002 A10 =
8.67092e-002 A12 = -5.34560e-002

26th page
K = -7.43625e + 005 A 4 = 9.14262e-002 A 6 = 5.63593e-002 A 8 = 1.53305e-003 A10 =
6.80592e-002 A12 = 3.20014e-002

Various data Zoom ratio 2.06
Wide angle Medium Telephoto focal length 1.00 1.45 2.06
F number 2.79 3.26 4.00
Half angle of view 51.27 41.66 32.82
Image height 1.25 1.29 1.33
Total lens length 8.79 8.39 8.55
BF 2.41 2.84 3.46

d 7 1.31 0.53 0.07
d12 0.01 0.34 0.67
d18 0.72 0.35 0.02
d26 2.41 2.84 3.46

Entrance pupil position 1.10 1.08 1.12
Exit pupil position -3.28 -1.96 -1.28
Front principal point position 1.92 2.09 2.29
Rear principal point position 1.41 1.39 1.40

Zoom lens group data group Start surface Focal length Lens configuration length Front principal point position Rear principal point position
1 1 -1.62 1.27 -0.01 -1.08
2 8 2.39 1.28 0.60 -0.43
3 13 -2.60 0.60 0.03 -0.36
4 19 2.16 1.19 0.08 -0.66

Single lens Data lens Start surface Focal length
1 1 -1.45
2 3 -2.46
3 4 25.94
4 6 2.48
5 8 -1.94
6 9 1.46
7 11 3.46
8 14 -3.46
9 16 -1.13
10 17 1.32
11 19 1.40
12 20 -5.15
13 22 -2.28
14 23 1.74
15 25 -4.17

Numerical example 4
Unit mm

Surface data surface number rd nd νd Effective diameter θgF
1 1.640 0.07 1.43875 95.0 2.23 0.5340
2 1.133 0.27 1.94
3 * 1.883 0.08 1.53000 55.8 1.91 0.5499
4 1.056 0.57 1.68
5 -2.967 0.07 1.92286 18.9 1.66 0.6495
6 3.038 0.39 1.65
7 3.400 0.35 1.83400 37.2 1.88 0.5776
8 -3.059 0.04 1.88
9 -10.734 0.10 1.61800 63.3 1.79 0.5441
10 2.070 (variable) 1.71
11 3.323 0.19 1.84666 23.9 1.72 0.6218
12 -27.668 (variable) 1.71
13 4.490 0.13 1.84666 23.9 1.59 0.6218
14 26.591 0.69 1.56
15 -1.402 0.09 1.76182 26.5 1.27 0.6136
16 -18.997 0.01 1.31
17 36.740 0.22 1.67790 55.3 1.32 0.5472
18 -1.573 0.01 1.33
19 -6.029 0.11 1.67790 54.9 1.29 0.5458
20 * -2.546 (variable) 1.29
21 (Aperture) ∞ 0.36 0.78
22 1.790 0.19 1.76182 26.5 0.86
23 -1.294 0.01 0.86
24 -1.251 0.07 1.83400 37.2 0.85
25 1.040 0.81 0.85
26 -5.557 0.40 1.49700 81.5 1.53
27 -1.000 0.01 1.58
28 -1.195 0.16 1.83400 37.2 1.58
29 -2.042 0.24 1.78
30 4.871 0.41 1.49700 81.5 2.15
31 -2.721 0.01 2.17
32 4.733 0.07 1.85026 32.3 2.16
33 1.660 0.56 1.56907 71.3 2.08
34 -4.605 0.20 2.08
35 ∞ 1.80 1.51633 64.1 2.01
36 ∞ 0.00 2.01
37 ∞ 1.29 1.69680 55.5 2.01
38 ∞ 0.13 2.01
Image plane ∞

Aspheric data 3rd surface
K = 5.34490e-001 A 4 = 4.04499e-002 A 6 = 1.89834e-002 A 8 = -8.72731e-003 A10 =
1.44328e-002

20th page
K = -6.25526e-001 A 4 = 4.68053e-003 A 6 = -5.91062e-003 A 8 = 1.48857e-002 A10 =
-9.64299e-003

Various data Zoom ratio 1.35
Wide angle Medium Telephoto focal length 1.00 1.15 1.35
F number 3.10 3.10 3.10
Half angle of view 36.04 32.29 28.32
Image height 0.73 0.73 0.73
Total lens length 11.33 11.33 11.33
BF 2.28 2.28 2.28

d10 0.17 0.11 0.08
d12 1.05 0.60 0.06
d20 0.04 0.54 1.11

Entrance pupil position 1.66 1.69 1.78
Exit pupil position 32.34 32.34 32.34
Front principal point position 2.69 2.89 3.18
Rear principal point position -0.87 -1.02 -1.22

Zoom lens group data group Start surface Focal length Lens configuration length Front principal point position Rear principal point position
1 1 -1.19 1.93 0.61 -0.96
2 11 3.48 0.19 0.01 -0.09
3 13 3.62 1.25 0.90 -0.26
4 21 2.32 6.58 2.50 -1.22

Single lens Data lens Start surface Focal length
1 1 -8.69
2 3 -4.67
3 5 -1.60
4 7 1.97
5 9 -2.79
6 11 3.48
7 13 6.31
8 15 -1.98
9 17 2.22
10 19 6.39
11 22 1.01
12 24 -0.67
13 26 2.38
14 28 -3.75
15 30 3.57
16 32 -3.02
17 33 2.21
18 35 0.00
19 37 0.00

Numerical example 5
Unit mm

Surface data surface number rd nd νd Effective diameter θgF
1 2.086 0.07 1.49700 81.5 2.23 0.5375
2 1.158 0.25 1.91
3 * 2.029 0.10 1.53000 55.8 1.88 0.5499
4 1.158 0.51 1.70
5 -2.998 0.07 1.92286 18.9 1.70 0.6495
6 4.388 (variable) 1.72
7 4.469 0.33 1.83400 37.2 2.06 0.5776
8 -3.821 0.01 2.06
9 5.489 0.07 1.56907 71.3 1.97 0.5451
10 2.001 (variable) 1.88
11 2.691 0.15 1.84666 23.9 1.88 0.6218
12 4.786 (variable) 1.85
13 3.114 0.15 1.84666 23.9 1.74 0.6218
14 8.382 0.75 1.72
15 -1.870 0.07 1.73800 32.3 1.39 0.5899
16 1.924 0.01 1.41
17 1.948 0.25 1.67790 55.3 1.41 0.5472
18 -6.120 0.01 1.42
19 40.919 0.21 1.67790 54.9 1.42 0.5458
20 * -1.888 (variable) 1.42
21 (Aperture) ∞ 0.49 0.85
22 1.638 0.24 1.75520 27.5 0.97
23 -1.258 0.01 0.95
24 -1.225 0.10 1.83400 37.2 0.95
25 1.077 0.80 0.92
26 -6.766 0.38 1.49700 81.5 1.49
27 -1.015 0.01 1.53
28 -1.177 0.07 1.80440 39.6 1.53
29 -2.396 0.07 1.68
30 5.864 0.38 1.49700 81.5 1.90
31 -2.073 (variable) 1.92
32 4.556 0.07 1.85026 32.3 1.92
33 1.549 0.48 1.56907 71.3 1.87
34 -4.557 0.18 1.87
35 ∞ 1.80 1.51633 64.1 2.01
36 ∞ 0.00 2.01
37 ∞ 1.29 1.69680 55.5 2.01
38 ∞ 2.23 2.01
Image plane ∞

Aspheric data 3rd surface
K = 9.55134e-002 A 4 = 4.78643e-002 A 6 = 2.08420e-002 A 8 = -7.21609e-003 A10 =
1.34171e-002

20th page
K = -5.22145e-001 A 4 = 7.03530e-004 A 6 = -3.53651e-003 A 8 = 1.85919e-003 A10 =
-1.46518e-003

Various data Zoom ratio 1.35
Wide angle Medium Telephoto focal length 1.00 1.18 1.35
F number 3.10 3.13 3.16
Half angle of view 36.04 31.66 28.32
Image height 0.73 0.73 0.73
Total lens length 11.59 11.59 11.59
BF 2.23 2.23 2.23

d 6 0.63 0.62 0.61
d10 0.28 0.13 0.09
d12 1.11 0.58 0.04
d20 0.04 0.61 1.11
d31 0.04 0.15 0.24

Entrance pupil position 1.58 1.61 1.66
Exit pupil position -206.39 -353.86 -779.27
Front principal point position 2.57 2.79 3.01
Rear principal point position -0.89 -1.07 -1.24

Zoom lens group data group Start surface Focal length Lens configuration length Front principal point position Rear principal point position
1 1 -0.96 1.00 0.58 -0.25
2 7 4.32 0.41 -0.03 -0.26
3 11 6.97 0.15 -0.10 -0.18
4 13 4.11 1.45 0.93 -0.43
5 21 4.60 2.56 3.00 1.52
6 32 7.73 3.83 0.28 -2.20

Single lens Data lens Start surface Focal length
1 1 -5.36
2 3 -5.28
3 5 -1.90
4 7 2.50
5 9 -5.56
6 11 6.97
7 13 5.72
8 15 -1.27
9 17 2.20
10 19 2.66
11 22 0.97
12 24 -0.67
13 26 2.35
14 28 -2.94
15 30 3.12
16 32 -2.77
17 33 2.09
18 35 0.00
19 37 0.00

Numerical example 6
Unit mm

Surface data surface number rd nd νd Effective diameter θgF
1 2.958 0.15 1.59282 68.6 4.58 0.5441
2 1.928 0.36 3.62
3 2.254 0.15 1.49700 81.5 3.58 0.5375
4 1.409 0.70 2.76
5 2.370 0.15 1.43875 94.9 2.70 0.5340
6 * 0.728 0.73 2.17
7 10.281 0.35 1.92286 18.9 2.17 0.6495
8 2.041 0.09 1.89
9 3.322 0.35 1.91082 35.3 1.89 0.5821
10 13.807 0.40 1.81
11 2.011 0.15 1.80 100 35.0 1.54 0.5864
12 0.998 0.51 1.72047 34.7 1.37 0.5834
13 -2.526 0.01 1.27
14 -2.311 0.28 1.61800 63.3 1.26 0.5441
15 0.783 0.36 1.65412 39.7 1.01 0.5737
16 -5.439 0.55 0.96
17 (Aperture) ∞ 0.04 0.85
18 9.124 0.15 1.83400 37.2 0.84
19 1.175 0.01 0.82
20 1.172 0.40 1.49700 81.5 0.83
21 -0.597 0.15 1.83400 37.2 0.83
22 -5.452 0.01 0.97
23 4.954 0.38 1.49700 81.5 1.04
24 -0.942 0.01 1.16
25 * -2.560 0.21 1.71736 29.5 1.24
26 -1.681 (variable) 1.35
Image plane ∞

Aspheric data 6th surface
K = -7.02972e-001 A 4 = -4.62867e-002 A 6 = -5.26266e-002 A 8 = 4.92532e-003 A10 =
-4.07881e-002

25th page
K = 5.42875e + 000 A 4 = -2.95663e-002 A 6 = 1.81113e-002 A 8 = -4.76595e-002 A10 =
-2.93450e-002

Various data Zoom ratio 1.00

Focal length 1.00
F number 2.90
Angle of view 87.35
Statue height 21.60
Total lens length 9.51
BF 2.82

d26 2.82

Entrance pupil position 2.03
Exit pupil position -1.76
Front principal point position 2.81
Rear principal point position 1.82

Single lens Data lens Start surface Focal length
1 1 -9.89
2 3 -8.05
3 5 -2.46
4 7 -2.82
5 9 4.73
6 11 -2.65
7 12 1.06
8 14 -0.91
9 15 1.07
10 18 -1.63
11 20 0.86
12 21 -0.82
13 23 1.63
14 25 6.21

The optical system of each of the above embodiments can be used for either a projection optical system for a projector or a photographing optical system of an imaging apparatus. As mentioned above, although preferable embodiment of this invention was described, this invention is not limited to these embodiment, A various deformation | transformation and change are possible within the range of the summary.

  Next, an embodiment in which the optical system of the present invention is applied to an imaging apparatus (camera system) (optical apparatus) will be described with reference to FIG. In FIG. 11, reference numeral 10 denotes an imaging lens having the optical systems of the first, second, and third embodiments. The optical system 1 is held by a lens barrel 2 that is a holding member. Reference numeral 20 denotes a camera body. The camera body includes a quick return mirror 3 that reflects the light beam from the imaging lens 10 upward, a focusing plate 4 that is disposed at an image forming position of the imaging lens 10, and a pentagon that converts an inverted image formed on the focusing plate 4 into an erect image. A roof prism 5 is provided. Further, it is constituted by an eyepiece 6 for observing the erect image.

  Reference numeral 7 denotes a photosensitive surface, on which a solid-state imaging device (photoelectric conversion device) such as a CCD sensor or a CMOS sensor, or a silver salt film is disposed. At the time of photographing, the quick return mirror 3 is retracted from the optical path, and an image is formed on the photosensitive surface 7 by the photographing lens 10.

  Next, an embodiment in which the optical system of the present invention is applied to a projection apparatus (projector) will be described with reference to FIG. The figure shows a projection lens in which optical system embodiments 4 and 5 of the present invention are applied to a three-plate color liquid crystal projector, and image information of a plurality of color lights based on a plurality of liquid crystal display elements is synthesized through a color synthesizing means. The projection apparatus which carries out expansion projection on the screen surface is shown.

  In FIG. 12, a color liquid crystal projector 100 is a prism 200 as a color synthesizing unit for RGB light beams from R, G, and B, and R, G, and B. Then, it is synthesized into one optical path and projected onto the screen 400 using the projection lens 300 composed of the optical system described above. Thus, by applying the optical systems of Numerical Examples 1 to 5 to a digital camera, a projector, or the like, it is possible to realize a projection device (optical apparatus) having high optical performance.

L1 1st lens group L2 2nd lens group L3 3rd lens group L4 4th lens group L5 5th lens group L6 6th lens group L2a 2nd lens group front group L2b 2nd lens group back group IP Reduction side conjugate surface, Or image plane SP aperture stop GB glass block ΔS sagittal image plane ΔM meridional image plane

Claims (16)

A first lens group having a negative refractive power disposed on the most enlargement side; and a stop disposed on a reduction side of the first lens group, wherein the first lens group includes a plurality of negative lenses. ,
The maximum and minimum Abbe numbers of the negative lens materials included in the first lens group are ν _{n, max} , ν _{n, min} , respectively _, the focal length of the entire system at the wide angle end is f _W , and the enlargement side from the stop The number of lenses existing in the lens is ib, and among the ib lenses, in order from the magnification side, the refractive power of the i-th lens is φ _i , and the Abbe number and partial dispersion ratio of the material of the i-th lens are The partial dispersion ratio difference Δθ _i is Δθ _i = θ _{gF, i} − (0.6438−0.001682ν _i ), respectively, with ν _i and θ _{gF, i.}
And when
3.3 <ν _{n, max} / ν _{n, min} <6.5
A zoom lens characterized by satisfying Of the negative lenses included in the first lens group, when the Abbe number of the material of the lens is a refractive index n _d for the d-line of the material of the negative lens takes the minimum value [nu _{n, min,}
1.8 < _nd <2.5
The zoom lens according to claim 1, wherein the following conditional expression is satisfied. The first lens group includes at least one positive lens, the refractive power of at least one positive lens included in the first lens group is φ _P , and the Abbe number and partial dispersion ratio of the material are ν _P and θ _gFP , respectively. And the partial dispersion ratio difference Δθ _P is Δθ _P = θ _gFP − (0.6438−0.001682ν _P )
And when
−0.0002 <f _W · φ _P · Δθ _P / ν _P <0.0000
The zoom lens according to claim 1, wherein the following conditional expression is satisfied. When there are a plurality of positive lenses on the reduction side from the stop and the maximum and minimum Abbe numbers of the materials of the positive lens located on the reduction side from the stop are ν _{p, max} and ν _{p, min} ,
2.5 <ν _{p, max} / ν _{p, min} <6.5
The zoom lens according to claim 1, wherein the following conditional expression is satisfied. The zoom lens is in order from the magnification side to the reduction side,
A first lens unit having a negative refractive power;
A second lens unit having a positive refractive power;
A third lens unit having a positive refractive power;
A fourth lens unit having a positive refractive power;
5. The zoom lens according to claim 1, wherein, during zooming, the first lens group and the lens group disposed closest to the reduction side are immovable. 6. A first lens group having a negative refractive power disposed on the most enlargement side; and a stop disposed on a reduction side of the first lens group, wherein the first lens group includes a plurality of negative lenses. , Having a plurality of positive lenses on the reduction side from the stop,
The maximum and minimum Abbe numbers of the negative lens material included in the first lens group are ν _{n, max} and ν _{n, min} , respectively, and the maximum Abbe number of the material of the positive lens located on the reduction side from the stop. Ν _{p, max} and ν _{p, min} , respectively _, the focal length of the entire system at the wide-angle end is f _W , the number of lenses existing on the magnification side from the stop is ib, and among the ib lenses In order from the enlargement side, the refractive power of the i-th lens is φ _i , the Abbe number and partial dispersion ratio of the i-th lens material are ν _i and θ _{gF, i} , respectively _, and the partial dispersion ratio difference Δθ _i is Δθ _i = θ _{gF, i} − (0.6438−0.001682ν _i )
And when
3.3 <ν _{n, max} / ν _{n, min} <6.5
2.5 <ν _{p, max} / ν _{p, min} <6.5
A zoom lens characterized by satisfying From the enlargement side to the reduction side,
A first lens unit having a negative refractive power;
A second lens unit having a positive refractive power;
A third lens unit having a negative refractive power;
A fourth lens unit having a positive refractive power;
During zooming, the distance between adjacent lens groups changes,
Before SL an aperture stop disposed on the reduction side than the first lens group, the first lens unit includes a plurality of negative lenses,
The maximum and minimum Abbe numbers of the negative lens material included in the first lens group are ν _{n, max} and ν _{n, min} , respectively _, the focal length of the entire system at the wide angle end is f _W , and the enlargement side from the stop The number of lenses existing in the lens is ib, and among the ib lenses, in order from the magnification side, the refractive power of the i-th lens is φ _i , and the Abbe number and partial dispersion ratio of the material of the i-th lens are The partial dispersion ratio difference Δθ _i is Δθ _i = θ _{gF, i} − (0.6438−0.001682ν _i ), respectively, with ν _i and θ _{gF, i.}
And when
3.3 <ν _{n, max} / ν _{n, min} <6.5
To meet the
Zoom lens, wherein a call. An optical apparatus characterized by having a zoom lens of any one of claims 1-7. A single-focus lens in which the distance between the lens arranged on the most reduction side and the reduction-side focal point is larger than the focal length of the entire system, and has a stop.
The lens group on the enlargement side than the stop is a front group, the front group has a plurality of negative lenses,
The maximum and minimum Abbe numbers of the negative lens materials included in the front group are ν _{n, max} and ν _{n, min} , the focal length of the entire system is f, and the number of lenses included in the front group is ib. In this order from the magnifying side of the ib lenses and ib lenses, the refractive power of the i-th lens is φ _i , and the Abbe number and the partial dispersion ratio of the material of the i-th lens are ν _i , θ _{gF, i} , respectively. And the partial dispersion ratio difference Δθ _i is Δθ _i = θ _{gF, i} − (0.6438−0.001682ν _i ).
And when
3.3 <ν _{n, max} / ν _{n, min} <6.5
A single-focus lens characterized by satisfying Among the plurality of negative lenses, the two negative lenses in which the Abbe number of the lens material has the maximum value ν _{n, max} and the minimum value ν _{n, min} are the reduction side of the first lens disposed on the most magnifying side. The single-focus lens according to claim 9, wherein the single-focus lens is disposed continuously from the enlargement side to the reduction side and moves along the same locus as the first lens during focusing. When the refractive index at the d-line of the material of the negative lens Abbe number of the material of the lens of the negative lens included in the front group the minimum value [nu _{n, min} and n _d,
1.8 < _nd <2.5
The single focus lens according to claim 9 or 10, wherein the following conditional expression is satisfied. The front group has at least one positive lens, the refractive power of at least one positive lens included in the front group is φ _P , the Abbe number of the material and the partial dispersion ratio are ν _P and θ _gFP , respectively. The ratio difference Δθ _{P is changed} to Δθ _P = θ _gFP − (0.6438−0.001682ν _P ).
And when
−0.0002 <f _W · φ _P · Δθ _P / ν _P <0.0000
The single focus lens according to claim 9, wherein the following conditional expression is satisfied. When there are a plurality of positive lenses on the reduction side from the stop and the maximum and minimum Abbe numbers of the materials of the positive lens located on the reduction side from the stop are ν _{p, max} and ν _{p, min} ,
2.5 <ν _{p, max} / ν _{p, min} <6.5
The single focus lens according to claim 9, wherein the following conditional expression is satisfied. A single-focus lens in which the distance between the lens arranged on the most reduction side and the reduction-side focal point is larger than the focal length of the entire system, and has a stop.
The lens group on the enlargement side than the stop is a front group, the front group has a plurality of negative lenses,
The maximum and minimum Abbe numbers of the negative lens materials included in the front group are ν _{n, max} , ν _{n, min} , the focal length of the entire system is f, and the number of lenses included in the front group is ib In this order from the magnifying side of the ib lenses and ib lenses, the refractive power of the i-th lens is φ _i , and the Abbe number and the partial dispersion ratio of the material of the i-th lens are ν _i , θ _{gF, i} , respectively. And the partial dispersion ratio difference Δθ _i is Δθ _i = θ _{gF, i} − (0.6438−0.001682ν _i ).
And when
3.3 <ν _{n, max} / ν _{n, min} <6.5
The filling,
Among the plurality of negative lenses, the two negative lenses in which the Abbe number of the lens material has the maximum value ν _{n, max} and the minimum value ν _{n, min} are the reduction side of the first lens disposed on the most magnifying side. The single-focus lens according to claim 1, wherein the single-focus lens is arranged continuously from the enlargement side to the reduction side and moves along the same locus as the first lens during focusing. A single-focus lens in which the distance between the lens arranged on the most reduction side and the reduction-side focal point is larger than the focal length of the entire system, and has a stop.
The lens group on the enlargement side than the stop is a front group, the front group has a plurality of negative lenses,
A plurality of positive lenses on the reduction side of the diaphragm;
The maximum value and the minimum value of the Abbe number of the negative lens material included in the front group are ν _{n, max} and ν _{n, min} , respectively, and the maximum value of the Abbe number of the positive lens material located on the reduction side from the stop The minimum values are ν _{p, max} , ν _{p, min} , the focal length of the entire system is f, the number of lenses included in the front group is ib, and the ib lenses in order from the enlargement side among the ib lenses The refractive power of the lens is φ _i , the Abbe number and partial dispersion ratio of the i-th lens material are ν _i and θ _{gF, i} , respectively _, and the partial dispersion ratio difference Δθ _i is Δθ _i = θ _{gF, i} − (0.6438-0.001682ν _i )
And when
3.3 <ν _{n, max} / ν _{n, min} <6.5
2.5 <ν _{p, max} / ν _{p, min} <6.5
A single-focus lens characterized by satisfying An optical apparatus comprising the single focus lens according to any one of claims 9 to 15 .