JP2002318346A - Variable soft focusing lens system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a variable soft focusing lens system by which the change of a focal distance and the movement of a focus are eliminated before/after the changeover of a normal photographing state and a soft effect photographing state, and also complicated movement is not needed. SOLUTION: This system has the master lens group 10 of positive power and the soft effect group 20 of negative power in order from an object side, and the soft effect group 20 has at least two sub groups 20P and 20N of positive and negative power which are independently movable to the master lens group 10. A diaphragm S exists in the master lens group 10. Two sub groups 20P and 20N are moved to the master lens group 10 and the other sub group so that the focal distance and a focal position are not changed before/after the changeover of the normal photographing state and the soft effect photographing state in which spherical aberration larger than that in the normal photographing state is caused.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a soft focus lens system, and more particularly to a soft focus effect photographing (soft effect photographing).
And a variable soft focus lens system capable of switching between normal shooting without a soft focus effect.

[0002]

2. Description of the Related Art A variable soft focus lens system of this type has been proposed in, for example, Japanese Patent Application Laid-Open No. 8-86957. However, this lens system has a problem that the focal position shifts and the focal length (f) changes due to switching between normal shooting and soft effect shooting. When the focal position shifts, the focus must be re-adjusted before and after the switching, and if this is to be corrected automatically automatically, the mechanism must be complicated.

In the lens system disclosed in JP-A-8-248310, a change in focal length caused by switching between normal shooting and soft effect shooting is canceled by moving another lens system. However, this is a kind of zoom mechanism, and similarly causes the mechanism to be complicated.

[0004]

SUMMARY OF THE INVENTION It is an object of the present invention to provide a variable soft focus lens system which does not change the focal length and does not require a complicated movement even when switching to a soft effect photographing state. .

[0005]

SUMMARY OF THE INVENTION A variable soft focus lens system according to the present invention has a positive power master lens group and a negative power soft effect group, and the soft effect group is independent of the master lens group. At least positive and negative 2
The two sub-groups are switchable between a normal photographing state and a soft effect photographing state that generates a spherical aberration larger than the normal photographing state. Each of the groups is characterized by moving with respect to the master lens group and the other sub-group before and after switching between the normal imaging state and the soft effect imaging state so as not to change the focal length and the focal position.

The reason why the soft effect group is set to negative power is as follows. The soft effect group switches between the normal shooting state and the soft effect shooting state by changing the interval between the positive and negative sub-groups. When the soft effect group has a positive power, the change of the focal length and the change of the focal position are corrected by moving the soft effect group to the image plane side. However, moving the soft effect group to the image plane side is not preferable because the diameter of a light beam passing through the soft effect group is reduced, so that spherical aberration is reduced and the generated soft effect is canceled. To avoid this, if the positive power is increased to correct the focal shift accompanying the soft effect with a small amount of movement, the positive power of the master lens group will be weakened.
The two principal points are shifted toward the image side, and as a result, the overall lens length of the entire system increases. There is a degree of freedom in the context of the master lens group and the soft effect group. In one embodiment, the master lens group and the soft effect group are located in this order from the object side,
Position the aperture in the master lens group. It is desirable that the two sub-groups of the soft effect group include a positive single lens and a negative single lens in order from the object side, which form an air lens having a meniscus shape concave toward the stop.

The variable soft focus lens system according to the present invention preferably satisfies the following conditional expressions (1) and (2). (1) 0.05 <d0 / f <0.50 (2) -4.0 <fB0 / f <-0.5, where d0 is on the optical axis of the master lens group and the soft effect group in a normal shooting state , FB0: focal length of the soft effect group in the normal photographing state, f: focal length of the entire system in the normal photographing state.

It is desirable that the focusing for the change in the subject distance be performed by the whole lens advance or the front lens advance by which only the master lens group is extended. In particular, when the front lens is extended, the focus unit and the soft effect unit are completely independent, and the mechanical configuration can be simplified. When the soft effect group is located behind the stop, the front lens can be extended, which is advantageous in aberration correction.

[0009]

FIG. 1 shows an embodiment of a variable soft focus lens system according to the present invention. In order from the object side, a master lens group 10 having a positive power and a soft effect group 20 having a negative power are provided.
Has a positive sub-group 20P and a negative sub-group 20N that are independently movable with respect to the master lens group 10. The stop S exists in the master lens group 10. Master lens group 1
The combined power of 0 and the soft effect group 20 is positive. In the present embodiment, the positive sub-group 20P and the negative sub-group 20N are moved along different trajectories with respect to the master lens group 10, respectively, to generate a normal photographing state and a spherical aberration larger than the normal photographing state. Switch to the effect shooting state. On the basis of the normal shooting state, the positive sub-group 20P and the negative sub-group 20N move toward the object side when moving to the soft effect shooting state, and the moving speed of the positive sub-group 20P is lower than the moving speed of the negative sub-group 20N. Fast, before and after switching between normal shooting state and soft effect shooting state,
Do not change the focal length and focal position. Normal sub group 20P
The solution that the negative lens group 20N moves without changing the focal length and the focal position before and after switching between the normal shooting state and the soft effect shooting state is that the master lens group 10 has positive power. The soft effect group 20 has negative power, the positive sub group 20P and the negative sub group 2
0N exists as long as it satisfies the condition that it is independently movable with respect to the master lens group 10.

FIG. 1, FIG. 5, FIG. 9, FIG. 13, FIG. 17, FIG.
1, 25, 29 and 33, the master lens group 10 and the soft effect group 20 are located in this order from the object side, and the stop S is located in the master lens group. The positive sub-group 20P and the negative sub-group 20N comprise, in order from the object side, a positive single lens and a negative single lens, and the positive single lens and the negative single lens constitute an air lens concave toward the stop S. are doing.

Thus, the positive sub-group 20P and the negative sub-group 2P
If 0N constitutes an air lens having a concave shape toward the stop S, the thickness of the air lens is reduced in a normal photographing state, and spherical aberration that occurs largely under the first surface which is a converging surface is reduced. Since the spherical aberration that occurs largely over the second surface, which is the diverging surface, can be canceled by each other, normal imaging without a soft effect can be performed. On the other hand, when switching to the soft effect shooting state, if the thickness of the air lens is increased, only the height of incidence on the second surface decreases,
Occurrence of over spherical aberration on the second surface is reduced, and under spherical aberration remains as a whole, so that soft effect imaging can be performed. If the air lens is not concave toward the stop S, changing the thickness of the air lens changes the angle of incidence on the surface other than the height of the light beam incident on the second surface of the air lens. Various aberrations also change, which is not preferable. .

In the conventional variable soft focus lens system, switching between the normal photographing state and the soft effect photographing state changes only the thickness of the air lens without changing the distance between the master lens group and the soft effect group. The focal length change and the focal point shift occurred before and after the switching, and the reason is analyzed as follows. The image created by the master lens group is considered to be an object for the soft effect group. When the thickness of the concave air lens is changed, the distance between the lenses having power is changed, so that the focal length of the soft effect group is changed. If the distance between the master lens group and the soft effect group is constant, the magnification of the soft effect group also changes. When the magnification changes, the distance between the object and the image also changes. Therefore, the focal length and the focal position of the entire system change.

On the other hand, according to this embodiment, switching between the normal photographing state and the soft effect photographing state not only changes the thickness of the air lens of the soft effect group, but also changes the soft effect group and the master lens group. The relative position with respect to is also changed. Therefore, switching can be performed without changing both the focal length and the focal position. The reason for this is that in the above, the distance between the master lens group and the soft effect group is also changed, and the magnification of the soft effect group and the distance between the object images are kept constant. From the imaging formula based on the principal point, −1 / a + 1 / b = 1 / f and the lateral magnification m = −b / a, the condition for keeping the object-image interval (IO) constant is the first principal point. Is the distance HH from to the second principal point: IO = −a + b + HH = −a ² 2 / (a + f) + HH =
The condition for keeping the constant magnification constant is given by m = -f / (a + f) = constant. a: distance from the object point to the first principal point; b: distance from the second principal point to the image point; f: focal length of the entire system. If the variable soft focus optical system satisfies the above conditions, the positive sub group 20P and the negative sub group 20
By moving only N in a predetermined relationship, the focal length of the entire system and the paraxial focus position can be kept constant.

Conditional expression (1) is a condition for exhibiting a necessary soft photographing effect while suppressing the change of the focal length and the movement of the focal position to a practically sufficient level. If the lower limit of conditional expression (1) is exceeded and the master lens group and the soft effect group are too close, the change in focal length and the movement of the focal position when the soft amount is secured cannot be corrected. On the other hand, if the distance exceeds the upper limit, it is difficult to secure the back focus, and the diameter of the soft effect group increases.

Conditional expression (2) is a condition for enabling a sufficient soft effect and normal photographing while reducing the amount of movement of the two sub-groups of the soft effect group. If the power of the soft effect group becomes too weak below the lower limit of the conditional expression (2), the movement amount for correcting the focal length change and the focus movement during the soft effect photographing becomes too large. If the power of the soft effect group becomes too strong beyond the upper limit, it becomes difficult to correct aberrations at the time of normal shooting, particularly at the time of short-distance shooting.

Next, a specific embodiment will be described. D in the chromatic aberration (axial chromatic aberration) diagram and the lateral chromatic aberration diagram represented by spherical aberration
Line, g line, and c line are aberrations for each wavelength,
S is sagittal, M is meridional. In the table, F _NO is the F number in the normal shooting state, f is the focal length of the entire system, f _B is the back focus, r is the radius of curvature, d is the lens thickness or lens interval, and N _d is the refractive index of the d line. , Ν represents the Abbe number.

Embodiment 1 FIGS. 1 to 4 show Embodiment 1 of a variable soft focus lens system according to the present invention. FIG. 1 is a lens configuration diagram in a normal shooting state at infinity,
Table 1 shows the numerical data. 2 is a diagram of various aberrations of the lens configuration of FIG. 1, and FIGS. 3 and 4 are a diagram of various aberrations and a diagram of coma aberration in a soft effect photographing state at infinity. Surface Nos. 1 to 11
The master lens group 10 and the surfaces No. 12 to 16 are the soft effect group 20. The data of D12 and D14 show the numerical values of the normal shooting state at infinity and the soft effect shooting state at infinity. Focusing on a short-distance object point is performed by moving the entire master lens group 10 and the soft effect group 20 toward the object along the optical axis. The stop S is located at 6.33 from the sixth surface to the image side.

[0018]

TABLE 1 _{F NO = 1: 2.9 f =} 85.00-84.38 f B = 40.30-46.43 surface _{No. r d N d ν 1 43.183} 5.49 1.59240 68.3 2 159.905 0.10 - - 3 39.991 4.01 1.59240 68.3 4 128.469 0.84 - - 5 464.265 1.50 1.63636 35.4 6 48.223 10.52--7 -42.737 1.57 1.54814 45.8 8 40.000 3.47---9 -62.096 2.27 1.77250 49.6 10 -41.822 0.10--11 45.031 7.00 1.61800 63.4 12 -51.971 13.55-4.97--13 -57.503 49.6 14 -30.612 2.99-5.44--15 -25.303 1.50 1.66672 48.3 16 -128.427---

[Embodiment 2] FIGS. 5 to 8 show Embodiment 2 of the variable soft focus lens system according to the present invention. FIG. 5 is a lens configuration diagram in a normal shooting state at infinity,
Table 2 shows the numerical data. FIG. 6 is a diagram of various aberrations of the lens configuration of FIG. 5, and FIGS. 7 and 8 are a diagram of various aberrations and a diagram of coma aberration in a soft effect photographing state at infinity. The basic lens configuration is the same as that of the first embodiment, but focusing to a short distance is performed by moving the master lens group 10 toward the object along the optical axis. The stop S is 2.25 from the sixth surface to the image side.
Position.

[0020]

TABLE 2 _{F NO = 1: 2.9 f =} 85.00-85.11 f B = 39.41-48.90 surface _{No. r d N d ν 1 46.256} 5.97 1.59240 68.3 2 495.714 0.10 - - 3 51.395 4.64 1.59240 68.3 4 745.851 2.92 - - 5 -202.047 1.53 1.66680 33.0 6 73.641 5.02--7 -52.751 1.20 1.54814 45.8 8 43.498 8.83--9 -62.610 2.79 1.72916 54.7 10 -38.877 0.39--11 63.141 6.34 1.61800 63.4 12 -78.249 12.46-1.00--13 -203.119 4.60 1.77250 49.6 14 -38.627 3.38-5.34--15 -32.341 1.50 1.78590 44.2 16 742.357---

Third Embodiment FIGS. 9 to 12 show a third embodiment of the variable soft focus lens system according to the present invention. This is an embodiment in which the present invention is applied to a medium camera (6 × 4.5 format). FIG. 9 is a diagram showing a lens configuration in a normal shooting state at infinity, and Table 3 shows numerical data thereof. FIG. 10 is a diagram showing various aberrations of the lens configuration of FIG.
FIG. 12 shows various aberration diagrams and a coma aberration diagram in a soft effect photographing state at infinity. The basic lens configuration is the same as that of the first embodiment, but focusing to a short distance is performed by moving the master lens group 10 toward the object along the optical axis. The stop S is at a position 11.52 from the sixth surface to the image side.

[0022]

TABLE 3 _{F NO = 1: 2.9 f =} 127.13-126.79 f B = 59.53-70.67 surface _{No. r d N d ν 1 90.614} 8.00 1.59240 68.3 2 1851.497 0.10 - - 3 52.050 8.36 1.59240 68.3 4 257.017 1.86 - - 5 539.121 2.00 1.63636 35.4 6 60.628 18.22--7 -65.698 3.00 1.54814 45.8 8 63.348 6.26--9 -76.996 3.51 1.77250 49.6 10 -54.154 0.10--11 77.321 10.08 1.61800 63.4 12 -94.550 14.42-1.00--13 -141.249 6.70 1.77 49.6 14 -49.614 4.31-6.58--15 -42.647 1.90 1.66672 48.3 16 -902.750---

Fourth Embodiment FIGS. 13 to 16 show a fourth embodiment of the variable soft focus lens system according to the present invention. FIG. 13 is a diagram showing a lens configuration in a normal shooting state at infinity, and Table 4 shows numerical data thereof. FIG. 14 is a diagram of various aberrations of the lens configuration of FIG. 13, and FIGS. 15 and 16 are a diagram of various aberrations and a diagram of coma aberration in a soft effect photographing state at infinity. The basic lens configuration and the focusing operation to a short distance are the same as in the first embodiment. Also, the stop S is moved from the sixth surface to the image side.
69 position.

[0024]

[Table 4] F _NO = 1: 2.9 f = 85.00-84.78 f _B = 39.97-43.15 Surface No. rd N _d ν 1 42.478 5.00 1.59240 68.3 2 164.267 0.10--3 36.618 5.11 1.59240 68.3 4 665.712 0.80--5 174.296 1.50 1.66680 33.0 6 54.801 5.45--7 -52.405 1.20 1.57501 41.5 8 32.552 8.57--9 -48.596 3.12 1.72916 54.7 10 -34.699 1.00--11 55.934 5.80 1.61800 63.4 12 -79.969 5.98-1.04--13 -71.420 4.5 39.4 14 -33.466 4.98-6.74--15 -29.218 1.50 1.78590 44.2 16 -167.924---

Embodiment 5 FIGS. 17 to 20 show Embodiment 5 of the variable soft focus lens system of the present invention. This is an embodiment in which the present invention is applied to a medium camera (6 × 4.5 format). FIG. 17 is a diagram showing a lens configuration in a normal shooting state at infinity, and Table 5 shows numerical data thereof. FIG. 18 is a diagram illustrating various aberrations of the lens configuration of FIG. 17;
FIGS. 19 and 20 are graphs showing various aberrations and a coma in the infinity soft effect photographing state. The basic lens configuration is the same as that of the first embodiment, but focusing to a short distance is performed by moving the master lens group 10 toward the object along the optical axis. The stop S is located at 8.01 from the sixth surface to the image side.

[0026]

TABLE 5 _{F NO = 1: -2.8 f =} 120.00-119.39 f B = 57.09-65.63 surface _{No. r d N d ν 1 66.654} 7.07 1.48749 70.2 2 263.545 0.10 - - 3 63.484 8.50 1.59240 68.3 4 -235.927 2.86 - -5 -131.030 2.00 1.62247 36.1 6 80.351 15.19--7 -50.758 2.00 1.53077 48.3 8 92.864 4.38--9 -77.452 4.70 1.56907 71.3 10 -39.789 0.10--11 88.387 7.72 1.77250 49.6 12 -136.937 12.75-1.00--13- 164.836 7.86 1.58144 40.7 14 -44.945 4.52-7.70--15 -39.356 2.00 1.65016 39.4 16 1734.700---

Sixth Embodiment FIGS. 21 to 24 show a sixth embodiment of the variable soft focus lens system according to the present invention. This is an embodiment in which the present invention is applied to a medium camera (6 × 4.5 format). FIG. 21 is a diagram showing the lens configuration in a normal shooting state at infinity, and Table 6 shows its numerical data. FIG. 22 is a diagram of various aberrations of the lens configuration of FIG. 21;
FIG. 23 and FIG. 24 are graphs showing various aberrations and a coma aberration in a soft effect photographing state at infinity. The basic lens configuration is the same as that of the first embodiment, but focusing to a short distance is performed by moving the master lens group 10 toward the object along the optical axis. The stop S is located at 8.54 from the sixth surface to the image side.

[0028]

TABLE 6 _{F NO = 1: 2.9-2.8 f =} 120.00-119.20 f B = 57.01-69.53 surface _{No. r d N d ν d N} d 1 68.465 7.36 1.48749 70.2 - 2 -1274.200 0.10 - - - 3 44.736 7.13 1.56907 71.3-4 228.248 1.98---5 -14530.447 2.00 1.59551 39.2-6 45.685 16.65---7 -58.149 2.00 1.55690 48.6-8 64.115 4.27---9 -64.665 3.02 1.77250 49.6-10 -47.726 0.10-- 69.770 7.17 1.61800 63.4-12 -76.074 18.09-2.94----13 -86.793 5.30 1.69680 55.5-14 -38.312 3.13-5.76----15 -33.707 2.00 1.57135 53.0 1.57135 16 -247.683----

Seventh Embodiment FIGS. 25 to 28 show a variable soft focus lens system according to a seventh embodiment of the present invention. This is an embodiment in which the present invention is applied to a medium camera (6 × 4.5 format). FIG. 25 is a diagram showing the lens configuration in a normal shooting state at infinity, and Table 7 shows its numerical data. FIG. 26 is a diagram showing various aberrations of the lens configuration of FIG. 25;
FIG. 27 and FIG. 28 are graphs showing various aberrations and a coma aberration in the soft effect photographing state at infinity. The basic lens configuration is the same as that of the first embodiment, but focusing to a short distance is performed by moving the master lens group 10 toward the object along the optical axis. The stop S is located at 18.42 from the sixth surface to the image side.

[0030]

TABLE 7 _{F NO = 1: 2.8 f =} 128.77-127.97 f B = 59.01-74.27 surface _{No. r d N d ν 1 88.476} 7.87 1.59240 68.3 2 4220.690 0.10 - - 3 60.165 7.09 1.59240 68.3 4 185.748 3.01 - - 5 748.715 3.69 1.63636 35.4 6 66.377 23.30--7 -53.236 1.92 1.54814 45.8 8 66.111 4.64--9 -71.475 2.92 1.77250 49.6 10 -51.870 0.10--11 72.466 8.00 1.61800 63.4 12 -70.418 21.45-4.13--13 -142.507 49.6 14 -42.693 2.45-4.51--15 -37.631 1.90 1.66672 48.3 16 -656.041---

Eighth Embodiment FIGS. 29 to 32 show an eighth embodiment of the variable soft focus lens system according to the present invention. This is an embodiment in which the present invention is applied to a medium camera (6 × 4.5 format). FIG. 29 is a diagram showing a lens configuration in a normal shooting state at infinity, and Table 8 shows numerical data thereof. FIG. 30 is a diagram showing various aberrations of the lens configuration of FIG. 29;
FIG. 31 and FIG. 32 are diagrams showing various aberrations and coma in the soft effect photographing state at infinity. The basic lens configuration is the same as that of the first embodiment, but focusing to a short distance is performed by moving the master lens group 10 toward the object along the optical axis. The stop S is located at a position 18.37 from the sixth surface to the image side.

[0032]

TABLE 8 _{F NO = 1: 2.9 f =} 126.15-125.39 f B = 59.00-74.09 surface _{No. r d N d ν 1 78.531} 7.72 1.59240 68.3 2 2457.373 0.10 - - 3 60.091 5.95 1.59240 68.3 4 165.043 2.99 - - 5 698.849 3.20 1.63636 35.4 6 64.917 22.84--7 -51.602 1.90 1.54814 45.8 8 67.739 4.50---9 -69.838 3.04 1.77250 49.6 10 -49.943 0.10--11 71.916 8.00 1.61800 63.4 12 -71.916 20.13-2.95--13 -148.994 49.6 14 -42.854 2.53-4.62--15 -37.560 1.90 1.66672 48.3 16 -1024.286---

Ninth Embodiment FIGS. 33 to 36 show a ninth embodiment of the variable soft focus lens system according to the present invention. This is an embodiment in which the present invention is applied to a medium camera (6 × 4.5 format). FIG. 33 is a diagram showing a lens configuration in a normal shooting state at infinity, and Table 9 shows numerical data thereof. FIG. 34 is a diagram showing various aberrations of the lens configuration of FIG. 33;
FIG. 35 and FIG. 36 are a diagram of various aberrations and a diagram of coma aberration in a soft effect photographing state at infinity. The basic lens configuration is the same as that of the first embodiment, but focusing to a short distance is performed by moving the master lens group 10 toward the object along the optical axis. The stop S is at a position of 19.09 from the sixth surface to the image side.

[0034]

TABLE 9 _{F NO = 1: 2.9 f =} 124.68-124.06 f B = 59.09-73.61 surface _{No. r d N d ν 1 88.489} 7.56 1.61800 63.4 2 -1254.882 0.10 - - 3 63.947 6.04 1.61800 63.4 4 152.749 2.51 - - 5 1529.856 3.00 1.66680 33.0 6 74.978 23.89--7 -46.520 1.90 1.53172 48.9 8 69.625 4.51--9 -71.118 3.19 1.69680 55.5 10 -47.415 0.10--11 72.842 7.84 1.59240 68.3 12 -64.805 20.59-4.08--89 -176.857 1.77250 49.6 14 -43.848 2.75-4.74--15 -37.951 1.90 1.66672 48.3 16 2809.636---

Table 10 shows values for each conditional expression in each embodiment.

[Table 10]

As is clear from Table 10, the numerical values of Examples 1 to 9 satisfy the conditional expressions (1) and (2), and as shown in the aberration diagrams, Aberrations are well corrected. In particular, no detrimental asymmetry is observed in the coma diagram in the soft effect photographing state, and it is clear that a beautiful soft focus effect by spherical aberration can be obtained.

[0037]

According to the variable soft focus lens system of the present invention, even when switching to the soft effect photographing state, there is no change in focal length and no focal shift, and no variable soft focus lens is required. A system can be obtained.

[Brief description of the drawings]

FIG. 1 is a lens configuration diagram of a variable soft focus lens system according to a first exemplary embodiment of the present invention in a normal imaging state at infinity.

FIG. 2 is a diagram illustrating various aberrations of the lens configuration of FIG. 1;

FIG. 3 is a diagram illustrating various aberrations when the lens configuration in FIG. 1 is switched to an infinity soft effect imaging state.

FIG. 4 is a coma aberration diagram when the lens configuration in FIG. 1 is switched to an infinity soft effect shooting state.

FIG. 5 is a lens configuration diagram of a variable soft focus lens system according to a second exemplary embodiment of the present invention in a normal infinity shooting state.

6 is a diagram illustrating various aberrations of the lens configuration in FIG. 5;

FIG. 7 is a diagram illustrating various aberrations when the lens configuration in FIG. 5 is switched to an infinity soft effect imaging state.

8 is a coma aberration diagram when the lens configuration in FIG. 5 is switched to an infinity soft effect shooting state.

FIG. 9 is a lens configuration diagram of a variable soft focus lens system according to a third embodiment of the present invention in a normal infinity shooting state.

10 is a diagram illustrating various aberrations of the lens configuration in FIG. 9;

11 is a diagram illustrating various aberrations when the lens configuration in FIG. 9 is switched to an infinity soft effect imaging state.

12 is a coma aberration diagram when the lens configuration in FIG. 9 is switched to an infinity soft effect imaging state.

FIG. 13 is a diagram illustrating a lens configuration of a variable soft focus lens system according to a fourth embodiment of the present invention in a normal imaging state at infinity.

14 is a diagram illustrating various aberrations of the lens configuration in FIG. 13;

15 is a diagram illustrating various aberrations when the lens configuration in FIG. 13 is switched to an infinity soft effect imaging state.

16 is a coma aberration diagram when the lens configuration in FIG. 13 is switched to an infinity soft effect imaging state.

FIG. 17 is a diagram illustrating a lens configuration of a variable soft focus lens system according to a fifth exemplary embodiment of the present invention in a normal imaging state at infinity.

18 is a diagram illustrating various aberrations of the lens configuration in FIG. 17;

19 is a diagram of various aberrations when the lens configuration in FIG. 17 is switched to an infinity soft effect imaging state.

20 is a coma aberration diagram when the lens configuration in FIG. 17 is switched to an infinity soft effect imaging state.

FIG. 21 is a diagram illustrating a lens configuration of a variable soft focus lens system according to a sixth embodiment of the present invention in a normal infinity shooting state.

FIG. 22 is a diagram illustrating various aberrations of the lens configuration in FIG. 21;

23 is a diagram of various aberrations when the lens configuration in FIG. 21 is switched to an infinity soft effect imaging state.

24 is a coma aberration diagram when the lens configuration in FIG. 21 is switched to an infinity soft effect imaging state.

FIG. 25 is a diagram illustrating a lens configuration of a variable soft focus lens system according to a seventh embodiment of the present invention in a normal infinity shooting state.

FIG. 26 is a diagram illustrating various aberrations of the lens configuration in FIG. 25;

27 is a diagram of various aberrations when the lens configuration in FIG. 25 is switched to an infinity soft effect imaging state.

28 is a coma aberration diagram when the lens configuration in FIG. 25 is switched to an infinity soft effect imaging state.

FIG. 29 is a diagram illustrating a lens configuration of an eighth embodiment of the variable soft focus lens system according to the present invention in a normal imaging state at infinity.

FIG. 30 is a diagram illustrating various aberrations of the lens configuration in FIG. 29;

31 is a diagram of various aberrations when the lens configuration in FIG. 29 is switched to an infinity soft effect imaging state.

32 is a coma aberration diagram when the lens configuration in FIG. 29 is switched to an infinity soft effect imaging state.

FIG. 33 is a diagram illustrating a lens configuration of a ninth embodiment of the variable soft-focus lens system according to the present invention in a normal imaging state at infinity.

FIG. 34 is a diagram illustrating various aberrations of the lens configuration in FIG. 33;

35 is a diagram of various aberrations when the lens configuration in FIG. 33 is switched to an infinity soft effect imaging state.

36 is a coma aberration diagram when the lens configuration in FIG. 33 is switched to an infinity soft effect imaging state.

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[Procedure amendment]

[Submission date] April 23, 2002 (2002.4.2
3)

[Procedure amendment 1]

[Document name to be amended] Statement

[Correction target item name] 0013

[Correction method] Change

[Correction contents]

On the other hand, according to this embodiment, switching between the normal photographing state and the soft effect photographing state not only changes the thickness of the air lens of the soft effect group, but also changes the soft effect group and the master lens group. The relative position with respect to is also changed. Therefore, switching can be performed without changing both the focal length and the focal position. The reason for this is that in the above, the distance between the master lens group and the soft effect group is also changed, and the magnification of the soft effect group and the distance between the object images are kept constant. From official imaged relative to the main points for a soft effect group, -1 / a + 1 / b = 1 / f s, and from the lateral magnification m = -b / a, to object-image interval (IO) to constant The condition is an interval H from the first principal point to the second principal point.
If H, IO = -a + b + HH = - a 2 / (a + f s) + HH = conditions constant constant _{magnification, m = - f s / (} a + f s) = is given by a constant. a: the distance from the object point to the first principal point; b: the distance from the second principal point to the image point; f _s : the focal length of the soft effect group . In Suyo satisfy the above conditions can be maintained by moving only the positive sub group 20P and the negative sub group 20N soft effect group 20 in a predetermined relationship, the focal distance and the paraxial focus position of the entire system constant .

[Procedure amendment 2]

[Document name to be amended] Statement

[Correction target item name] 0017

[Correction method] Change

[Correction contents]

Embodiment 1 FIGS. 1 to 4 show Embodiment 1 of a variable soft focus lens system according to the present invention. FIG. 1 is a lens configuration diagram in a normal shooting state at infinity,
Table 1 shows the numerical data. 2 is a diagram of various aberrations of the lens configuration of FIG. 1, and FIGS. 3 and 4 are a diagram of various aberrations and a diagram of coma aberration in a soft effect photographing state at infinity. Surface Nos. 1 to 12
The master lens group 10 and the surfaces Nos. 13 to 16 are the soft effect group 20. The data of D12 and D14 show the numerical values of the normal shooting state at infinity and the soft effect shooting state at infinity. Focusing on a short-distance object point is performed by moving the entire master lens group 10 and the soft effect group 20 toward the object along the optical axis. The stop S is located at 6.33 from the sixth surface to the image side.

[Procedure amendment 3]

[Document name to be amended] Statement

[Correction target item name] 0026

[Correction method] Change

[Correction contents]

[0026]

TABLE 5 _{F NO = 1: 2.8 f =} 120.00-119.39 f B = 57.09-65.63 surface _{No. r d N d ν 1 66.654} 7.07 1.48749 70.2 2 263.545 0.10 - - 3 63.484 8.50 1.59240 68.3 4 -235.927 2.86 - - 5 -131.030 2.00 1.62247 36.1 6 80.351 15.19--7 -50.758 2.00 1.53077 48.3 8 92.864 4.38--9 -77.452 4.70 1.56907 71.3 10 -39.789 0.10--11 88.387 7.72 1.77250 49.6 12 -136.937 12.75-1.00--13 -164.836 7.86 1.58144 40.7 14 -44.945 4.52-7.70--15 -39.356 2.00 1.65016 39.4 16 1734.700---

[Procedure amendment 4]

[Document name to be amended] Statement

[Correction target item name] 0028

[Correction method] Change

[Correction contents]

[0028]

TABLE 6 _{F NO = 1: 2.9 f =} 120.00-119.20 f B = 57.01-69.53 surface _{No. r d N d ν d N} d 1 68.465 7.36 1.48749 70.2 - 2 -1274.200 0.10 - - - 3 44.736 7.13 1.56907 71.3 -4 228.248 1.98---5 -14530.447 2.00 1.59551 39.2-6 45.685 16.65----7 -58.149 2.00 1.55690 48.6-8 64.115 4.27---9 -64.665 3.02 1.77250 49.6-10 -47.726 0.10--770 1.61800 63.4-12 -76.074 18.09-2.94----13 -86.793 5.30 1.69680 55.5-14 -38.312 3.13-5.76----15 -33.707 2.00 1.57135 53.0 1.57135 16 -247.683-----

Claims (4)

[Claims] 1. A master lens group having a positive power and a soft effect group having a negative power, wherein the soft effect group has at least two positive and negative sub-movements independently movable with respect to the master lens group. The two sub-groups are switchable between a normal shooting state and a soft effect shooting state that generates a spherical aberration larger than the normal shooting state, and the two sub-groups are A variable soft focus lens that moves with respect to the master lens group and the other sub group so as not to change the focal length and the focal position before and after switching between the normal shooting state and the soft effect shooting state, respectively. system. 2. The variable soft focus lens system according to claim 1, wherein the master lens group and the soft effect group are
Located in this order from the object side, the stop is located in the master lens group, and the two sub-groups of the soft effect group form an air lens having a concave meniscus shape toward the stop, in order from the object side, Variable soft focus lens system consisting of a positive single lens and a negative single lens. 3. The variable soft focus lens system according to claim 1, wherein the following conditional expressions (1) and (2) are satisfied. (1) 0.05 <d0 / f <0.50 (2) -4.0 <fB0 / f <-0.5, where d0 is on the optical axis of the master lens group and the soft effect group in a normal shooting state FB0: focal length of the soft effect group in the normal shooting state; f: focal length of the entire system in the normal shooting state. 4. The variable soft focus lens system according to claim 1, wherein the master lens group is a single lens or the entire system is a focus lens group.