JP2002062476A - Teleconverter lens - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a teleconverter lens which is used by attaching to a film unit with a telephoto type lens, is made light in weight and is made inexpensive. SOLUTION: This teleconverter lens 30 is composed of a resin lens that is made light in the weight and is made inexpensive. The teleconverter lens 30 is orderly composed of two-group type of a first lens group 31 incorporating at least one positive lens and having positive refracting power as a whole and a second lens group 32 consisting of one negative lens from an object side. When the focal distance of the first lens group 31 is set as f1, the focal distance of the second lens group 32 is set as f2, the center thickness of a lens whose thickness is largest in the first lens group 31 is set as d1 and the center thickness of the negative lens of the second lens group 32 is set as d2, the respective conditional expressions of '-2.0<=f1/f2<=-1.2' and '1.5<=d1/d2<=4.0' are satisfied.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention
The present invention relates to a teleconverter lens used by being attached to the front surface of a telephoto lens having a diameter of 1 mm.

[0002]

2. Description of the Related Art At present, a great number of types of cameras for photographing are sold according to their uses and functions. Recently, a film unit with a lens has been manufactured and sold by the present applicant so that photographing can be easily enjoyed. The film unit with lens is
An unexposed photographic film is built in the unit body that incorporates a photographic mechanism, such as a photographic lens and shutter device. It is widely used because of its convenience.

The film unit with a lens has an advantage that it can be provided at a low price, and has a very simple configuration because it needs to be manufactured at the lowest possible cost. For example, the taking lens is positioned and held on a lens holder having an aperture stop having a constant diameter, and its focus set position cannot be changed.

Some of such film units with lenses include Japanese Utility Model Laid-Open No. 2-104340 and Japanese Patent Laid-Open No. 7-2.
As described in Japanese Patent No. 30114, there is one provided with a telephoto lens. In a telephoto type lens-equipped film unit, the focal length of the photographing lens is set to about 100 mm in order to prevent the outer shape from becoming too large. Recently, the number of users who shoot baseball or soccer players from the stand has increased, and there has been an increasing demand for larger distant subjects. In order to satisfy such demands, it is necessary to further extend the focal length of the photographing lens to about 150 mm.

[0005]

However, if the focal length of the photographic lens is increased, the size of the film unit with the lens is inevitably increased, and the handling of the film unit with the lens is deteriorated. The storage space in the area must be secured widely. In addition, a large amount of molding material for the unit body is required, resulting in an increase in cost.

In a general camera such as a single-lens reflex camera, a dedicated teleconverter lens for changing a focal position to a long distance side is prepared. It is also possible to attach this teleconverter lens to a lens-fitted film unit for use. However, a teleconverter lens for a single-lens reflex camera is expensive and large and heavy, so it is difficult to use it by attaching it to a film unit with a lens.

The present invention has been made in view of the above circumstances, and has as its object to provide a lightweight and inexpensive teleconverter lens that can be used by attaching to a telephoto-type film unit with a lens.

[0008]

In order to achieve the above object, a teleconverter lens according to the present invention is constructed by combining resin lenses, and sequentially from the object side.
A first lens group including at least one positive lens and having a positive refractive power as a whole, and a second lens group including one negative lens, wherein the focal length of the first lens group is f
1, when the focal length of the second lens group is f2, the center thickness of the thickest lens in the first lens group is d1, and the center thickness of the negative lens in the second lens group is d2, -2.0 ≤ f1 / f2 ≤ -1.2 1.5 ≤ d1 / d2 ≤ 4.0.

In the teleconverter lens according to the present invention, the first lens group is composed of one positive lens having a convex surface facing the object side, the Abbe number of the first lens group is ν1, and the second lens group is When the Abbe number of the group is ν2, the condition that ν1> ν2 is satisfied.

According to a third aspect of the present invention, in the teleconverter lens, the first lens group includes, in order from the object side, a first lens having a positive refractive power with the convex surface facing the object side and a concave surface facing the image surface side. When the Abbe number of the first lens is ν11 and the Abbe number of the second lens is ν12, the condition of ν11> ν12 is satisfied.

According to a fourth aspect of the present invention, the teleconverter lens has an aspherical lens surface located closest to the object side in the first lens group.

[0012]

According to the present invention, by using a resin lens,
It constitutes a lightweight and inexpensive teleconverter lens. In addition, the teleconverter lens is configured in a two-group form, and a lens group located on the object side has a positive refractive power, and a lens group located on the image plane side has a negative refractive power. By adjusting the thickness, it is possible to make the lens shape easy to mold, and it is possible to suppress an increase in axial chromatic aberration.

If the lower limit of -2.0≤f1 / f2≤-1.2 is exceeded, the focal length of the first lens unit located on the object side becomes longer, so that the total length of the teleconverter lens becomes longer. . When the value exceeds the upper limit of the conditional expression, the positive refractive power becomes too strong, and it becomes impossible to maintain a good balance of various aberrations.

If the upper limit of the condition (1.5 ≦ d1 / d2 ≦ 4.0) is exceeded, the thickness of the lens in the first lens unit becomes too large, so that the sink is likely to occur during molding. It is difficult to maintain high precision, and the thickness of the negative lens constituting the second lens group is too thin, so that molding of the lens becomes difficult. If the lower limit of the conditional expression is exceeded, the thickness of the lens located closest to the object side in the first lens group becomes too thin, so that the chromatic aberration on the axis increases and cannot be suppressed.

In the case where the first lens group is constituted by one lens, a chromatic aberration can be favorably maintained by using a positive lens having a convex surface facing the object side and satisfying the condition ν1> ν2. If the above condition is not satisfied, both on-axis and lateral chromatic aberrations will increase.

When the first lens group is composed of two lenses, the first lens having a positive refractive power with the convex surface facing the object side and the negative refractive power with the concave surface facing the image surface side Second
By being composed of a lens and satisfying the condition ν11> ν12, chromatic aberration can be favorably maintained. If the above condition is not satisfied, the chromatic aberration on the axis and the magnification will not increase.

Further, by making the lens surface located closest to the object side in the first lens group aspherical, various aberrations can be easily corrected, and the lens performance can be improved.

[0018]

13. As shown in FIG. 13, a telephoto type lens-equipped film unit 10 has a photographing lens 11 and an objective finder 12 on the front surface, and a release button 13 and a film counter window 14 on the upper surface. Is provided. In addition, an eyepiece finder 15 is provided on the rear surface, and a part of a winding knob 16 is exposed. The focal length of the taking lens 11 is 100 m
A telephoto lens having an m and F number of 10 and an image height of 21.63 mm is used.

When a distant subject is to be photographed larger using the lens-fitted film unit 10, a special telephoto adapter 20 is provided on the front of the lens-fitted film unit 10.
Attach. The telephoto adapter 20 includes an adapter body 21
And a rubber string 22 attached thereto. Adapter body 2
Reference numeral 1 denotes a resin molded product, and the shape of the back surface is formed so as to follow the shape of the front surface of the film unit with lens 10. At the lower edge of the adapter main body 21, a claw portion 23 for hanging a central portion of the rubber cord 22 is provided. Connect the telephoto adapter 20 to the film unit 1 with lens
When the film unit 10 is attached to the lens unit 0, the rubber string 22 is made to make a round from the upper surface to the rear surface and the lower surface of the lens-fitted film unit 10 and hooked on the claw portion 23. Thus, the telephoto adapter 20 is positioned and held on the front surface of the lens-fitted film unit 10.

The adapter body 21 is provided with a teleconverter lens 30 and a finder field frame 25.
The teleconverter lens 30 changes the focal position of the photographing lens 11 to a long distance side, and is provided so as to be coaxial with the photographing lens 11 when the telephoto adapter 20 is attached to the film unit 10 with a lens. ing.
When the teleconverter lens 30 and the photographing lens 11 are used in combination, the focal length is increased to 150 mm without changing the image forming position of the subject image. Further, the finder field frame 25 is located in front of the objective finder 12, and restricts the finder field to define the photographing range.

As shown in FIG. 1, the taking lens 11 is positioned and held on the object side of the diaphragm 18, and the teleconverter lens 30 is positioned on the object side. The teleconverter lens 30 is formed by combining lenses made of resin and includes, in order from the object side, at least one positive lens, and a first lens group 31 having a positive refractive power as a whole.
And a second lens group 32 including one negative lens. In this teleconverter lens 30, the focal length of the first lens group 31 is f1, the focal length of the second lens group 32 is f2, the center thickness of the lens located closest to the object side in the first lens group 31 is d1, Assuming that the center thickness of the negative lens of the second lens group 32 is d2, the following conditional expressions are satisfied: −2.0 ≦ f1 / f2 ≦ −1.2 1.5 ≦ d1 / d2 ≦ 4.0 Is configured. First Embodiment In the teleconverter lens of the first embodiment shown in FIG. 1, the first lens group 31 is composed of a meniscus positive lens 41 having a convex surface facing the object side, and the second lens group 3
Reference numeral 2 denotes a meniscus negative lens 45 having a concave surface facing the image surface side. The meniscus positive lens 41 is made of acrylic resin, and the meniscus negative lens 45 is made of polycarbonate (P
C).

In the teleconverter lens of the first embodiment, in which the first lens group 31 is composed of one positive lens whose convex surface faces the object side, the Abbe number of the first lens group 31 is ν1,
When the Abbe number of the second lens group 32 is ν2, the condition of ν1> ν2 is satisfied.

The specifications of the teleconverter lens of the first embodiment are as follows.

F1 = 159.15 mm f2 = −109.93 mm d1 = 6.0 mm d2 = 3.0 mm “f1 / f2” and “d1 / d2” which are characteristic values of the present invention.
Are as follows: f1 / f2 = 159.15 / (− 109.93) ≒
−1.45 d1 / d2 = 6.0 / 3.0 = 2.0, and each conditional expression of −2.0 ≦ f1 / f2 ≦ −1.2 1.5 ≦ d1 / d2 ≦ 4.0 Meets.

Table 1 below shows the lens data of the teleconverter lens of the first embodiment. The surface number i is a number given to the surface of each lens in order from the object side, and the surface interval D represents the lens thickness or the air space between the next surface (unit: mm).

[0026]

[Table 1]

In Table 1, the symbol "*" shown in the column of radius of curvature
Represents an aspherical surface. Aspheric surface condition Z = ch ² / [1+ {1- (1 + K) c 2 h 2} 1/2 ]
+ Ah ² + Bh ⁶ + Ch ⁸ + Dh ¹⁰ . In the equation, c represents the reciprocal of the radius of curvature (= 1 / R), and h represents the height of the light beam from the optical axis. Table 2 shows the aspheric coefficient.

[0028]

[Table 2]

From Table 1, the Abbe number ν of the first lens group 31 is shown.
Since the Abbe numbers ν2 of the first and second lens groups 32 are (57.5) and (29.9), respectively, the teleconverter lens of the first embodiment satisfies the condition “ν1> ν2”. I have.

FIGS. 2 and 3 show aberration diagrams of the teleconverter lens of the first embodiment. 2A shows spherical aberration, FIG. 2B shows astigmatism, and FIG. 2C shows distortion. Symbols d and g in the spherical aberration diagram of FIG.
Are d-line (587.6 nm) and g-line (435.
8B), and symbols S and T in the astigmatism diagram of FIG. 3B represent aberrations with respect to the spherical and meridional image planes, respectively. FIG. 3 is a lateral aberration diagram, in which (A), (B), (C), and (D) are image height ratios (1.00), (0.70), (0. 50), (0.0
0), and the symbols d and g represent d, respectively.
Represents the aberration with respect to the line and the g-line. Note that each aberration was measured by positioning an ideal lens having a focal length of 100 mm at a position 23.5 mm from the lens surface of the teleconverter lens closest to the image plane. [Second Embodiment] FIG. 4 shows a second embodiment of the teleconverter lens of the present invention. In all the embodiments described below, the teleconverter lens 3 of the first embodiment is used.
The same members as 0 are denoted by the same reference numerals. In the second embodiment, as in the first embodiment, the imaging lens 11 has a focal length of 100 mm, an F-number of 10, and an image height of 21.
A 63 mm telephoto lens is used.

In the teleconverter lens of the second embodiment, the first lens group 31 comprises a biconvex lens 42, and the second lens group 32 comprises a biconcave lens 46. The biconvex lens 42 and the biconcave lens 46 are formed of acrylic resin and polycarbonate (PC), respectively. Also, in the teleconverter lens of the second embodiment, as in the first embodiment, when the Abbe number of the first lens group 31 is ν1 and the Abbe number of the second lens group 32 is ν2, ν1> ν2. Meet the conditions.

The specifications of the teleconverter lens of the second embodiment are as follows.

F1 = 139.91 mm f2 = −93.11 mm d1 = 5.0 mm d2 = 2.0 mm Characteristic values of the present invention, “f1 / f2” and “d1 / d2”
Are as follows: f1 / f2 = 139.91 / (− 93.11) ≒ −
1.50 d1 / d2 = 5.0 / 2.0 = 2.5, and the conditional expressions of −2.0 ≦ f1 / f2 ≦ −1.2 1.5 ≦ d1 / d2 ≦ 4.0 are satisfied. Meets

Tables 3 and 4 show lens data and aspheric coefficients of the teleconverter lens of the second embodiment.

[0035]

[Table 3]

[0036]

[Table 4]

As shown in Table 3, the Abbe number ν of the first lens group 31
Since the Abbe numbers ν2 of the first lens group 32 and the second lens group 32 are (57.5) and (29.9), the teleconverter lens of the second embodiment satisfies the condition “ν1> ν2”. I have.

FIGS. 5 and 6 show aberration diagrams of the teleconverter lens of the second embodiment. Each aberration was measured by positioning an ideal lens having a focal length of 100 mm at a position 23.5 mm from the lens surface of the teleconverter lens closest to the image plane. Third Embodiment FIG. 7 shows a third configuration example of the teleconverter lens of the present invention. In the third embodiment, as in the first embodiment, a telephoto lens having a focal length of 100 mm, an F-number of 10, and an image height of 21.63 mm is used as the taking lens 11. In the teleconverter lens of the third embodiment, the first lens group 31 includes a first lens 43 having a positive refractive power with a convex surface facing the object side, and a second lens 43 having a negative refractive power with a concave surface facing the image surface side. A lens 44 and two lenses, and the Abbe number of the first lens 43 is ν1
1. When the Abbe number of the second lens 44 is ν12, the condition of ν11> ν12 is satisfied.

As the first lens 43, a positive meniscus lens having a convex surface facing the object side is used, and as the second lens 44, a negative meniscus lens having a concave surface facing the image surface side is used. The second lens group 32 includes a negative meniscus lens 45 having a concave surface facing the image surface side. First lens 43,
The second lens 44 and the negative meniscus lens 45 are formed of acrylic resin, polycarbonate (PC), and acrylic resin, respectively.

The specifications of the teleconverter lens of the third embodiment are as follows.

F1 = 186.89 mm f2 = −129.44 mm d1 = 7.5 mm d2 = 3.0 mm “f1 / f2” and “d1 / d2” which are characteristic values of the present invention.
Are as follows: f1 / f2 = 186.89 / (− 129.44) ≒
−1.44 d1 / d2 = 7.5 / 3.0 = 2.5, and each conditional expression of −2.0 ≦ f1 / f2 ≦ −1.2 1.5 ≦ d1 / d2 ≦ 4.0 Meets.

The following Tables 5 and 6 show lens data and aspheric coefficients of the teleconverter lens of the third embodiment.

[0043]

[Table 5]

[0044]

[Table 6]

From Table 5, the Abbe number ν1 of the first lens 43 is shown.
Since the Abbe numbers ν12 of the first and second lenses 44 are (57.5) and (29.9), respectively, the teleconverter lens of the third embodiment satisfies the condition “ν11> ν12”. .

FIGS. 8 and 9 show aberration diagrams of the teleconverter lens of the third embodiment. Note that each aberration was measured by positioning an ideal lens having a focal length of 100 mm at a position 99.2 mm from the lens surface of the teleconverter lens closest to the image plane. Fourth Embodiment FIG. 10 shows a fourth embodiment of the teleconverter lens of the present invention. In the fourth embodiment, as in the first embodiment, a telephoto lens having a focal length of 100 mm, an F-number of 10, and an image height of 21.63 mm is used as the taking lens 11. In the teleconverter lens of the fourth embodiment, as in the third embodiment, the first lens group 31 includes two lenses, a first lens 43 having a positive refractive power and a second lens 44 having a negative refractive power. Where the Abbe number of the first lens 43 is ν11 and the second lens 44 is
When the Abbe number of ν12 is ν12, the condition of ν11> ν12 is satisfied.

In the fourth embodiment, a biconvex lens is used as the first lens 43, and a meniscus negative lens having a concave surface facing the image plane is used as the second lens 44. The second lens group 32 includes a negative meniscus lens 45 having a concave surface facing the image surface side. The first lens 43, the second lens 44, and the negative meniscus lens 45 are formed of acrylic resin, polycarbonate (PC), and acrylic resin, respectively.

The specifications of the teleconverter lens of the fourth embodiment are as follows.

F1 = 146.82 mm f2 = −94.44 mm d1 = 7.6 mm d2 = 4.0 mm “f1 / f2” and “d1 / d2” which are characteristic values of the present invention.
Are as follows: f1 / f2 = 146.82 / (− 94.44) ≒ −
1.55 d1 / d2 = 7.6 / 4.0 = 1.9, and the conditional expressions of −2.0 ≦ f1 / f2 ≦ −1.2 1.5 ≦ d1 / d2 ≦ 4.0 are satisfied. Meets

Tables 7 and 8 show lens data and aspherical coefficients of the teleconverter lens of the fourth embodiment.

[0051]

[Table 7]

[0052]

[Table 8]

As shown in Table 7, the Abbe number ν1 of the first lens 43
Since the Abbe numbers ν12 of the first lens 44 and the second lens 44 are (57.5) and (29.9), respectively, the teleconverter lens of the fourth embodiment satisfies the condition “ν11> ν12”. .

FIGS. 11 and 12 show aberration diagrams of the teleconverter lens of the fourth embodiment. Note that each aberration was measured by positioning an ideal lens having a focal length of 100 mm at a position 33.5 mm from the lens surface of the teleconverter lens closest to the image plane.

[0055]

As described above, since the teleconverter lens of the present invention is made of a resin lens, it can be made lightweight and inexpensive. Further, the teleconverter lens is configured in a two-group form, and the first lens group located on the object side has a positive refractive power, and the second lens group located on the image plane side has a negative refractive power, By adjusting the center thickness of each lens, it is possible to form the lens into a shape that is easy to mold, suppress an increase in axial chromatic aberration, and form a good subject image.

[Brief description of the drawings]

FIG. 1 is a lens configuration diagram showing a first embodiment of a teleconverter lens of the present invention.

FIG. 2 is an aberration diagram of the teleconverter lens of FIG. 1;
(A) shows spherical aberration, (B) shows astigmatism, and (C) shows distortion.

3A and 3B are lateral aberration diagrams of the teleconverter lens of FIG. 1, wherein FIG. 3A shows aberration at an image height ratio of 1.00, FIG. 3B shows aberration at an image height ratio of 0.70, and FIG. High ratio 0.5
And (D) represents aberration at an image height ratio of 0.0.

FIG. 4 is a lens configuration diagram showing a second embodiment of the teleconverter lens of the present invention.

FIG. 5 is an aberration diagram of the teleconverter lens of FIG. 4;
(A) shows spherical aberration, (B) shows astigmatism, and (C) shows distortion.

6A and 6B are lateral aberration diagrams of the teleconverter lens of FIG. 4, wherein FIG. 6A shows aberration at an image height ratio of 1.00, FIG. 6B shows aberration at an image height ratio of 0.70, and FIG. High ratio 0.5
And (D) represents aberration at an image height ratio of 0.0.

FIG. 7 is a lens configuration diagram showing a third embodiment of the teleconverter lens of the present invention.

8 is an aberration diagram of the teleconverter lens of FIG. 7,
(A) shows spherical aberration, (B) shows astigmatism, and (C) shows distortion.

9A and 9B are lateral aberration diagrams of the teleconverter lens of FIG. 7, wherein FIG. 9A shows aberration at an image height ratio of 1.00, FIG. 9B shows aberration at an image height ratio of 0.70, and FIG. High ratio 0.5
And (D) represents aberration at an image height ratio of 0.0.

FIG. 10 is a lens configuration diagram showing a fourth embodiment of the teleconverter lens of the present invention.

11A and 11B are aberration diagrams of the teleconverter lens of FIG. 10, in which FIG. 11A shows spherical aberration, FIG. 11B shows astigmatism, and FIG.
Represents distortion.

12A and 12B are lateral aberration diagrams of the teleconverter lens in FIG. 10, wherein FIG.
Represents aberration at an image height ratio of 0.70, and FIG.
50 shows the aberration at 50, and (D) shows the aberration at an image height ratio of 0.0.

FIG. 13 is a perspective view showing a telephoto adapter using the teleconverter lens of the present invention.

[Explanation of symbols]

 Reference Signs List 10 Film unit with lens 11 Photographing lens 20 Telephoto adapter 30 Teleconverter lens 31 First lens group 32 Second lens group 43 First lens 44 Second lens

Claims (4)

[Claims] 1. A teleconverter lens mounted on a front surface of a telephoto lens having a focal length of 100 mm and incorporated in a fixed focus type camera. The teleconverter lens is configured by combining resin lenses, and at least in order from an object side. The first lens group includes one positive lens and has a positive refractive power as a whole, and the second lens group includes one negative lens. The first lens group has a focal length of f1 and a second lens group. The focal length of the lens group is f2,
When the center thickness of the thickest lens in the first lens group is d1, and the center thickness of the negative lens in the second lens group is d2, −2.0 ≦ f1 / f2 ≦ −1.2 1.5 A teleconverter lens that satisfies the following conditional expressions: ≦ d1 / d2 ≦ 4.0. 2. The first lens group is composed of a single positive lens having a convex surface facing the object side. When the Abbe number of the first lens group is ν1 and the Abbe number of the second lens group is ν2. The teleconverter lens according to claim 1, wherein the following condition is satisfied: ν1> ν2. 3. The first lens group includes, in order from the object side,
A first lens having a positive refractive power with a convex surface facing the object side, and a second lens having a negative refractive power with a concave surface facing the image surface;
2. The teleconverter lens according to claim 1, wherein the following condition is satisfied when the Abbe number of the first lens is .nu.11 and the Abbe number of the second lens is .nu.12. 4. The teleconverter lens according to claim 1, wherein a lens surface located closest to the object side in said first lens group is made aspherical.