JP2002006213A - Close-up lens - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a close-up lens capable of photographing an object at a close distance of <40 cm when the close-up lens is used together with a semi-wide angle lens. SOLUTION: The close-up lens 20 is constituted of a 1st lens group 21 constituted of one negative lens, and a 2nd lens group 22 constituted of one positive lens. Provided that the focal distance of the 1st lens group 21 is expressed by (f1), the focal distance of the 2nd lens group 22 is expressed by (f2), the synthetic focal distance of the whole close up lens 20 is expressed by (f), the photographing magnification of the whole optical system including a photographing lens 10 is expressed by (β), the diagonal length of an exposure screen by the whole optical system including the photographing lens 10 is expressed by (d), a distance from the lens surface positioned closest to the image side of the 2nd lens group 22 to the incident pupil position of the photographing lens 10 is expressed by (Re), the following conditional expressions are satisfied; -2.0<=f1/f2<=-0.5, d/3f<=β<=d/f and 5<=Re<=30.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a close-up lens used by attaching to a front surface of a taking lens.

[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. For this reason, the film unit with a lens is set to focus so that standard shooting can be performed in more shooting opportunities.

A film unit with a lens having a built-in photographic film having a width of 35 mm has a focal length of 32 mm and an F
A quasi-wide angle lens having a number of about 10, an image height of 21.63 mm, and a diagonal half angle of view of 34 ° is used as a photographing lens. In the case of a built-in photo film having a width of 24 mm, the focal length is about 24 mm, the F-number is about 10,
A quasi-wide-angle lens having an image height of 17.25 mm and a diagonal half angle of view of 35 ° is used. Each of these lens-fitted film units is configured so that the object distances 1 to ∞ are focused in consideration of the depth of field.

[0005] In recent years, it has become possible not only to easily take a picture, but also to take a picture of a subject at a close distance, such as taking a portrait photograph or taking a close-up picture of a pet or plant while using a film unit with a lens. There is an increasing demand to do so. In order to satisfy these demands, the "Shooting Run that can also be used for close-up photography" (product name) is equipped with two shooting lenses, a normal shooting lens and a close-up shooting lens, which can be switched and used. Sold by the applicant. However, incorporating two photographic lenses not only increases the number of components but also requires that a switching mechanism be incorporated, which hinders the cost reduction of the film unit with lens.
In addition, as described above, the lens-equipped film unit is taken directly to the developing dealer after use, so that the user has to purchase a new lens-equipped film unit each time, resulting in a cost burden. Is big.

In a general camera such as a single-lens reflex camera, a dedicated adapter having a close-up lens for changing a focus setting position to a shorter distance side than usual is prepared, and this adapter is attached to a front surface of a photographing lens. This enables close-up photography. This adapter can be used by attaching it to a film unit with a lens. However, close-up lenses for SLR cameras are
It is designed to be used at about the same angle of view as a standard lens, so if this is used in combination with a quasi-wide-angle lens built into a film unit with a lens, the field curvature and distortion of a close-up lens will be reduced. Are increased, and a good subject image cannot be formed.

[0007]

Therefore, a close-up lens for changing the focus setting position of the quasi-wide-angle lens to a short distance side and a film unit with a lens provided with a dimming plate for dimming strobe light are provided. A close-up adapter, "two-shot adapter" (trade name) is sold by the present applicant. However, with this close-up adapter, close-up shooting with a minimum shooting distance of about 40 cm is the limit,
There is a demand for a further reduction in the shooting distance. For this reason,
A close-up lens as described in Japanese Patent Application Laid-Open No. 9-288233 has been devised. This close-up lens has a high photographing magnification, so that it can be photographed close to a subject, but has a small depth of field. However, there is a disadvantage that a good image cannot be formed when a three-dimensional object is photographed.

For example, in photographing a sample of a cloth or wallpaper, photographing a specimen of an insect, a plant, or the like, or photographing for observing a temporal change such as growth of fungi or crystals on a petri dish, etc.
In some cases, the shooting distance approaches 10 cm. When shooting at such a close distance is performed using a film unit with a lens to which the close-up adapter is attached, the shooting distance to the subject cannot be specified, so the size of the print image obtained from the negative film Will be significantly different from the real one.

The present invention has been made in view of the above circumstances, and when used in combination with a quasi-wide-angle lens, the present invention has been developed.
It is an object of the present invention to provide a close-up lens that enables photographing of a subject at a close distance from the camera.

[0010]

In order to achieve the above object, a close-up lens according to the present invention is incorporated in a fixed focus type camera, and is used by being attached to the front of a taking lens comprising a quasi-wide angle lens. An up lens, which includes, in order from the object side, a first lens group including one negative lens and a second lens group including one positive lens, and the focal length of the first lens group is f1, The focal length of the second lens group is f2, the combined focal length of the entire close-up lens is f, the magnification of the entire optical system including the photographing lens is β, and the diagonal length of the exposure screen of the entire optical system including the photographing lens is β. d, when the distance from the image-side lens surface of the positive lens to the entrance pupil position of the taking lens is Re, −2.0 ≦ f1 / f2 ≦ −0.5 d / 3f ≦ β ≦ d / f 5 ≦ Re ≦ 30 It is intended to satisfy the equation.

The close-up lens according to claim 2 is a first close-up lens comprising one negative lens in order from the object side.
The lens group includes a second lens group including a plurality of lenses including at least one positive lens, and has a positive refractive power as a whole. The focal length of the first lens group is f1, and the second lens group is The focal length is f2, the combined focal length of the entire close-up lens is f, the imaging magnification of the entire optical system including the imaging lens is β, the diagonal length of the exposure screen by the entire optical system including the imaging lens is d, and the second lens Assuming that the distance from the lens surface located closest to the image side of the group to the entrance pupil position of the taking lens is Re, −1.0 ≦ f1 / f2 ≦ −0.5 d / 3f ≦ β ≦ d / f 5 ≦ Re ≦ 30.

[0012]

The close-up lens is formed in a two-group form, and the first lens group located on the object side has a negative refractive power, and the second lens group located on the image side has a positive refractive power. When the second lens group is composed of one lens, the following conditional expression is satisfied: −2.0 ≦ f1 / f2 ≦ −0.5. When the second lens group is composed of a plurality of lenses, Satisfies the following conditional expression: −1.0 ≦ f1 / f2 ≦ −0.5, thereby suppressing an increase in distortion when used in combination with a quasi-wide-angle lens, and suppressing deterioration in field curvature and coma. be able to. If the lower limit of each conditional expression is exceeded, the focal length of the lens group located on the object side becomes longer, so that the overall length of the close-up lens becomes longer. If the upper limit is exceeded, the negative refracting power becomes too strong, and it becomes impossible to maintain a good balance of various aberrations.

[0013] Further, by setting the photographing magnification in the entire system including the quasi-wide-angle lens in the range of d / 3f ≦ β ≦ d / f, photographing at a close distance from 40 cm becomes possible and the photographing magnification is too large. It is possible to form a good subject image of an appropriate size that is not too small or too small.

By satisfying the following condition: 5 ≦ Re ≦ 30, on-axis and off-axis fluctuations of various aberrations can be suppressed and the balance can be maintained, and good optical performance can be obtained. If the lower limit of this conditional expression is exceeded, it is possible to reduce the lens diameter of the close-up lens, but on the other hand, there is a risk that the camera body will hit the lens surface of the second lens group located closest to the image. Occurs. If the upper limit is exceeded, the distance between the close-up lens and the photographing lens becomes too long more than necessary, and not only the overall length of the close-up lens becomes longer, but also the focal length of the close-up lens needs to be made longer, resulting in positive distortion. Increases and cannot be suppressed.

The quasi-wide-angle lens incorporated in the lens-fitted film unit is constructed so as not to cause extreme distortion at a normal photographing distance. When photographing is performed at a close distance, such as photographing for observing a temporal change in crystal or crystal, the pincushion type distortion becomes extremely large. Therefore, the close-up lens used in combination with this quasi-wide-angle lens has a distortion in the direction opposite to the distortion of the quasi-wide-angle lens, that is, a barrel-shaped distortion, and when combined with the quasi-wide-angle lens, It is desirable to constitute so as to cancel each other's distortion.

[0016]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS As shown in FIG. 1, a photographing lens 10, an objective finder 11, a strobe light emitting section 12, and a strobe charge switch 13 are provided on the front surface of a film unit 2 with a lens. A release button 14, a film counter plate 15, and a light guide 16 are provided on the upper surface. On the rear surface, a part of the eyepiece finder 17 and a part of the winding knob 18 are exposed. A quasi-wide-angle lens is used as the photographing lens 10, and its photographing distance is set to 0.9 m to infinity.

When taking a picture from a close distance using the film unit with lens 2, a dedicated close-up adapter 40 is attached to the front of the film unit 2 with lens. The close-up adapter 40 includes an adapter body 41 and an adapter frame 51. The adapter main body 41 is a resin molded product, and the shape on the back side is formed in accordance with the shape on the front surface of the film unit with lens 2. The adapter body 41 is provided with an opening 43 for a strobe charge changeover switch for exposing the strobe charge changeover switch 13 of the film unit 2 with a lens, and a close-up lens 20. The close-up lens 20 is fixed so as to be located on the photographing optical axis of the film unit 2 with a lens.

On the upper right side of the adapter body 41, a dimming plate 44
Is fixed. The light-attenuating plate 44 reduces the strobe light, and is located on the front surface of the strobe light-emitting unit 12 when attached to the film unit 2 with a lens, thereby preventing a failure in photographing due to overexposure during close-up photographing. In the present embodiment, the portion where the light reducing plate 44 is held is formed as an opening. However, instead of this opening, a number of slits may be formed, and the light reducing plate 44 may be fixed from the back side.

A rubber string 45 is provided on the upper edge of the adapter body 41.
Is attached, and a pair of claw portions 46 are provided at the lower edge portion so as to protrude from the lower edge portion. Close-up adapter 40 is attached to film unit 2 with lens
When attaching to the lens unit, the close-up adapter 40 is brought into contact with the front surface of the film unit 2 with the lens. Thereafter, the rubber string 45 is made to make a round from the upper surface to the back surface and then to the lower surface, and is hooked on the claw portion 46. Thus, the close-up adapter 40 is positioned and held on the front surface of the film unit 2 with the lens.

On the left and right sides of the front surface of the adapter main body 41, two connection portions 47 are formed, one on each side. The connecting portion 47 is formed in a key shape in cross section, so that an adapter frame 51 described later can be easily attached and detached.

The adapter frame 51 is made of a resin molded product. The adapter frame 51 includes a rectangular imaging frame 52 and substantially U-shaped support members 53 and 54. The shooting frame 52 is used to determine a shooting range of a subject image during close-up shooting. That is, eyepiece finder 1
7 can be clearly exposed on a photographic film without entering the photographing frame 52.
The support members 53 and 54 are provided integrally on the left and right of the photographing frame 52. Since the shooting distance is determined by the close-up lens 20, the height of the support members 53 and 54 is
It is configured to have the same shooting distance (for example, 0.1 m) when shooting by combining 0 and the close-up lens 20. For this reason, when the close-up lens 20 is mounted on the lens-fitted film unit 2 for photographing, close-up photographing is performed at an optimum photographing distance. In addition,
The adapter frame 51 may be fixed to the adapter main body 41, and in this case, may be a foldable type.

The close-up lens 20 is configured to have a barrel-shaped distortion. The photographic lens 10 used in the lens-fitted film unit 2 is configured so that extreme distortion does not occur at a normal photographic distance. When photographing is performed at a close distance, such as photographing for observing a target change, pincushion distortion becomes noticeable. For this reason, by attaching the close-up lens 20, distortion generated at the time of close-up shooting can be suppressed. The close-up lens 20 has a fixed magnification, and when photographing is performed by attaching the close-up lens 20 to the lens-fitted film unit 2, the subject image that has been developed and enlarged and printed on photographic paper can be almost the actual size.

FIG. 2 shows a first configuration example of a close-up lens 20 according to the present invention. The close-up lens 20 is used by being positioned on the object side of the taking lens 10 of the lens-fitted film unit 2. The taking lens 10 is formed of a quasi-wide-angle lens,
9 is positioned and held on the object side. The close-up lens 20 includes, in order from the object side, a first lens group 21 having a negative refractive power and a second lens group 22 having a positive refractive power.

In the first embodiment, the taking lens 10 is
The focal length is 25 mm, the F-number is 10, and the image height is 17.
A quasi-wide angle lens having a 25 mm diagonal half angle of view of 35 ° is used. The close-up lens 20 includes a first lens group 21 having a meniscus negative lens 31 having a convex surface facing the object side.
It consists of. The second lens group 22 includes a positive meniscus lens 35 having a convex surface facing the object side.

The close-up lens 20 has a focal length f1 of the first lens group 21, a focal length f2 of the second lens group 22, a combined focal length f of the entire close-up lens 20, and an optical system including the photographing lens 10. The photographing magnification of the whole system is β, the diagonal length of the exposure screen by the entire optical system including the photographing lens 10 is d, and the distance from the image side lens surface 35b of the positive meniscus lens 35 to the entrance pupil position of the photographing lens 10 is Re. And the following conditional expressions are satisfied: −2.0 ≦ f1 / f2 ≦ −0.5 d / 3f ≦ β ≦ d / f 5 ≦ Re ≦ 30

The specifications of the close-up lens of the first embodiment are as follows. f = 104.41 mm f1 = −55.52 mm f2 = 39.39 mm d = 34.51 mm β = 0.175

One of the characteristic values of the present invention, "f1 / f
The value of “2” is f1 / f2 = −55.52 / 39.39 ≒ −1.
41, which satisfies the condition “−2.0 ≦ f1 / f2 ≦ −0.5”.

The values of “d / 3f”, “d / f”, and “β” are as follows: d / 3f = 34.51 / (3 × 104.41)
0.110 d / f = 34.51 / 104.41 ≒ 0.331 β = 0.175, which satisfies the condition “d / 3f ≦ β ≦ d / f”.

Table 1 below shows the lens data of the close-up 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).

[0030]

[Table 1]

The photographing lens 10 is moved from the image-side lens surface 35b of the positive meniscus lens 35 forming the second lens group 22.
From Table 1, the distance Re to the entrance pupil position is expressed as “Re =
6.9 ", which satisfies the condition" 5 ≦ Re ≦ 30 ”.

FIGS. 3 and 4 show aberration diagrams of the close-up lens of the first embodiment. 3A shows spherical aberration, FIG. 3B shows astigmatism, and FIG. 3C 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 S and T in the astigmatism diagram of FIG. 3B represent aberrations with respect to the spherical and meridional image planes, respectively. FIG. 4 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 for the line and the g line. Each aberration was measured by positioning an ideal lens having a focal length of 24.8 mm at a position 3.9 mm on the object side of the diaphragm 19.

[Second Embodiment] FIG. 5 shows a second embodiment of the close-up lens of the present invention. In all the embodiments described below, the same members as those of the close-up lens 20 of the first embodiment are denoted by the same reference numerals. In the second embodiment, as in the first embodiment, the imaging lens 10 has a focal length of 25 mm, an F-number of 10,
A quasi-wide-angle lens having an image height of 17.25 mm and a diagonal half angle of view of 35 ° is used. The close-up lens 20 is
The first lens group 21 includes a negative lens 32 having concave surfaces on both sides. The second lens group 22 includes a positive meniscus lens 35 having a convex surface facing the object side.

The specifications of the close-up lens of the second embodiment are as follows. f = 59.21 mm f1 = −51.09 mm f2 = 29.35 mm d = 34.51 mm β = 0.350

The value of the characteristic value “f1 / f2” is f1 / f2 = −51.09 / 29.35 ≒ −1.
74, which satisfies the condition “−2.0 ≦ f1 / f2 ≦ −0.5”.

The values of “d / 3f”, “d / f” and “β” are as follows: d / 3f = 34.51 / (3 × 59.21)
0.194 d / f = 34.51 / 59.21 ≒ 0.583 β = 0.350, which satisfies the condition “d / 3f ≦ β ≦ d / f”.

Table 2 below shows the lens data of the close-up lens of the second embodiment.

[0038]

[Table 2]

The photographing lens 10 is moved from the image side lens surface 35b of the positive meniscus lens 35 forming the second lens group 22.
From Table 2, the distance Re to the entrance pupil position of
6.9 ", which satisfies the condition" 5 ≦ Re ≦ 30 ”.

FIGS. 6 and 7 show aberration diagrams of the close-up lens of the second embodiment. In addition, each aberration is calculated by using an ideal lens having a focal length of 24.8 mm by moving the ideal lens having a focal length of 3.9 mm to the object side of the stop 19.
mm.

Third Embodiment FIG. 8 shows a third embodiment of the close-up lens of the present invention. In the third embodiment, as in the first embodiment, the photographic lens 10 has a focal length of 25 mm, an F-number of 10, and an image height of 1
A quasi-wide-angle lens with a 7.25 mm half-angle of 35 ° diagonal is used. In the close-up lens 20, the first lens group 21 includes a negative lens 32 having concave surfaces on both sides. The second lens group 22 includes a positive meniscus lens 35 having a convex surface facing the object side.

The specifications of the close-up lens of the third embodiment are as follows. f = 191.69 mm f1 = −65.56 mm f2 = 50.55 mm d = 34.51 mm β = 0.074

The value of the characteristic value “f1 / f2” is f1 / f2 = −65.56 / 55.55 ≒ −1.
30, which satisfies the condition “−2.0 ≦ f1 / f2 ≦ −0.5”.

The values of “d / 3f”, “d / f”, and “β” are as follows: d / 3f = 34.51 / (3 × 191.69)
0.060 d / f = 34.51 / 191.69６９0.180 β = 0.074, which satisfies the condition “d / 3f ≦ β ≦ d / f”.

Table 3 below shows the lens data of the close-up lens of the third embodiment.

[0046]

[Table 3]

The image-taking lens 10 is moved from the image-side lens surface 35b of the positive meniscus lens 35 constituting the second lens group 22.
From Table 3, the distance Re to the entrance pupil position is “Re = 1
0.00 ", which satisfies the condition“ 5 ≦ Re ≦ 30 ”.

FIGS. 9 and 10 show aberration diagrams of the close-up lens of the third embodiment. In addition, each aberration is calculated by using an ideal lens having a focal length of 24.8 mm by using an ideal lens having a focal length of 24.8 mm.
The measurement was performed by positioning at a position of 9 mm.

Fourth Embodiment FIG. 11 shows a fourth embodiment of the close-up lens of the present invention. This fourth
In the embodiment, the focal length of the photographing lens 10 is 25 m.
A quasi-wide-angle lens having an m and F number of 10, an image height of 17.25 mm, and a diagonal half angle of view of 35 ° is used. In the close-up lens 20, the first lens group 21 includes a negative lens 32 having concave surfaces on both sides. The second lens group 22 includes a positive meniscus lens 35 having a convex surface facing the object side.

The specifications of the close-up lens of the fourth embodiment are as follows. f = 104.93 mm f1 = −60.71 mm f2 = 40.34 mm d = 34.51 mm β = 0.175

The value of the characteristic value “f1 / f2” is f1 / f2 = −60.71 / 40.34 ≒ −1.
50, which satisfies the condition “−2.0 ≦ f1 / f2 ≦ −0.5”.

The values of “d / 3f”, “d / f”, and “β” are as follows: d / 3f = 34.51 / (3 × 104.93)
0.110 d / f = 34.51 / 104.93９３0.329 β = 0.175, which satisfies the condition “d / 3f ≦ β ≦ d / f”.

Table 4 below shows the lens data of the close-up lens of the fourth embodiment.

[0054]

[Table 4]

The photographing lens 10 is moved from the image side lens surface 35b of the positive meniscus lens 35 forming the second lens group 22.
From Table 4, the distance Re to the entrance pupil position of “
5.5 ”, which satisfies the condition“ 5 ≦ Re ≦ 30 ”.

12 and 13 show aberration diagrams of the close-up lens according to the fourth embodiment. Each aberration was measured by positioning an ideal lens having a focal length of 24.8 mm at a position 3.9 mm on the object side of the diaphragm 19.

Fifth Embodiment FIG. 14 shows a fifth embodiment of the close-up lens of the present invention. This fifth
In the embodiment, the photographing lens 10 has a focal length of 32 m.
A quasi-wide-angle lens having an m and F number of 10, an image height of 21.63 mm, and a diagonal half angle of view of 34 ° is used. In the close-up lens 20, the first lens group 21 includes a negative lens 32 having concave surfaces on both sides. The second lens group 22 includes a positive meniscus lens 35 having a convex surface facing the object side.

The specifications of the close-up lens of the fifth embodiment are as follows. f = 192.48 mm f1 = −59.09 mm f2 = 46.86 mm d = 43.27 mm β = 0.118

The value of the characteristic value “f1 / f2” is as follows: f1 / f2 = −59.09 / 46.86 ≒ −1.
26, which satisfies the condition “−2.0 ≦ f1 / f2 ≦ −0.5”.

The values of “d / 3f”, “d / f”, and “β” are as follows: d / 3f = 43.27 / (3 × 192.48)
0.075 d / f = 43.27 / 192.48 ≒ 0.225 β = 0.118, which satisfies the condition “d / 3f ≦ β ≦ d / f”.

Table 5 below shows the lens data of the close-up lens of the fifth embodiment.

[0062]

[Table 5]

The photographing lens 10 is moved from the image-side lens surface 35b of the positive meniscus lens 35 forming the second lens group 22.
From Table 5, the distance Re to the entrance pupil position is “Re = 1”.
0.00 ", which satisfies the condition“ 5 ≦ Re ≦ 30 ”.

FIGS. 15 and 16 show aberration diagrams of the close-up lens according to the fifth embodiment. In addition, each aberration was measured by positioning an ideal lens having a focal length of 32.4 mm at a position of 3.8 mm on the object side of the diaphragm 19.

Sixth Embodiment FIG. 17 shows a sixth embodiment of the close-up lens of the present invention. This sixth
In the embodiment, the photographing lens 10 has a focal length of 32 m.
A quasi-wide-angle lens having an m and F number of 10, an image height of 21.63 mm, and a diagonal half angle of view of 34 ° is used. In the close-up lens 20, the first lens group 21 includes a negative lens 32 having concave surfaces on both sides. The second lens group 22 includes a positive meniscus lens 35 having a convex surface facing the object side.

The specifications of the close-up lens of the sixth embodiment are as follows. f = 96.56 mm f1 = −58.94 mm f2 = 38.81 mm d = 43.27 mm β = 0.279

The value of the characteristic value “f1 / f2” is f1 / f2 = −58.94 / 38.81 ≒ −1.
52, which satisfies the condition “−2.0 ≦ f1 / f2 ≦ −0.5”.

The values of “d / 3f”, “d / f” and “β” are as follows: d / 3f = 43.27 / (3 × 96.56)
0.149 d / f = 43.27 / 96.56 ≒ 0.448 β = 0.279, which satisfies the condition “d / 3f ≦ β ≦ d / f”.

Table 6 below shows the lens data of the close-up lens of the sixth embodiment.

[0070]

[Table 6]

The image-taking lens 10 is moved from the image-side lens surface 35b of the positive meniscus lens 35 constituting the second lens group 22.
From Table 6, the distance Re to the entrance pupil position is expressed as “Re =
8.00 ", which satisfies the condition" 5 ≦ Re ≦ 30 ”.

FIGS. 18 and 19 show aberration diagrams of the close-up lens according to the sixth embodiment. In addition, each aberration was measured by positioning an ideal lens having a focal length of 32.4 mm at a position of 3.8 mm on the object side of the diaphragm 19.

Seventh Embodiment FIG. 20 shows a seventh configuration example of a close-up lens according to the present invention, in which the second lens group is composed of two lenses. In the seventh embodiment, the photographing lens 10 has a focal length of 32 m.
A quasi-wide-angle lens having an m and F number of 10, an image height of 21.63 mm, and a diagonal half angle of view of 34 ° is used. In the close-up lens 20, the first lens group 21 includes a negative lens 32 having concave surfaces on both sides. The second lens group 22 includes two lenses: a positive lens 36 having convex surfaces on both sides, and a meniscus positive lens 37 having a convex surface facing the object side.

In the close-up lens of the seventh embodiment, the focal length of the first lens group 21 is f1, the focal length of the second lens group 22 is f2, the combined focal length of the entire close-up lens 20 is f, and the taking lens is The magnification of the entire optical system including the imaging lens 10 is β, the diagonal length of the exposure screen of the entire optical system including the imaging lens 10 is d, and the distance from the image-side lens surface 37 b of the positive lens 37 to the entrance pupil position of the imaging lens 10. Distance is R
When e is satisfied, the following conditional expressions are satisfied: −1.0 ≦ f1 / f2 ≦ −0.5 d / 3f ≦ β ≦ d / f 5 ≦ Re ≦ 30

The specifications of the close-up lens of the seventh embodiment are as follows. f = 51.47 mm f1 = −30.67 mm f2 = 41.00 mm d = 43.27 mm β = 0.558

The value of the characteristic value “f1 / f2” is f1 / f2 = −30.67 / 41.00 ≒ −0.0.
75, which satisfies the condition “−1.0 ≦ f1 / f2 ≦ −0.5”.

The values of “d / 3f”, “d / f” and “β” are as follows: d / 3f = 43.27 / (3 × 51.47)
0.280 d / f = 43.27 / 51.47 ≒ 0.841 β = 0.558, which satisfies the condition “d / 3f ≦ β ≦ d / f”.

Table 7 below shows the lens data of the close-up lens of the seventh embodiment.

[0079]

[Table 7]

The distance Re from the lens surface located closest to the image side of the second lens group 22, that is, the image side lens surface 37 b of the positive meniscus lens 37 to the entrance pupil position of the photographing lens 10 is shown in Table 7 as “Re = 15.00 ”, which satisfies the condition“ 5 ≦ Re ≦ 30 ”.

FIGS. 21 and 22 show aberration diagrams of the close-up lens according to the seventh embodiment. In addition, each aberration was measured by positioning an ideal lens having a focal length of 32.4 mm at a position of 3.8 mm on the object side of the diaphragm 19.

[0082]

As described above, according to the present invention, the close-up lens is formed in a two-group form, the lens group located on the object side has a negative refractive power, and the lens group located on the image side. Has a positive refractive power, and by adjusting the distribution of the refractive power of each lens group, suppresses the increase in distortion when used in combination with a quasi-wide-angle lens, and suppresses the deterioration of field curvature and coma. be able to. Also, by setting the photographing magnification of the entire system including the quasi-wide-angle lens to be within a certain range, photographing at a close distance from 40 cm becomes possible.
A good subject image can be formed with an appropriate size.

[Brief description of the drawings]

FIG. 1 is a perspective view showing a configuration of a close-up adapter using a close-up lens of the present invention.

FIG. 2 is a lens configuration diagram showing a first embodiment of a close-up lens of the present invention.

FIG. 3 is an aberration diagram of the close-up lens of FIG. 2;
(A) shows spherical aberration, (B) shows astigmatism, and (C) shows distortion.

4A and 4B are lateral aberration diagrams of the close-up lens of FIG. 2, wherein FIG. 4A shows aberration at an image height ratio of 1.00, FIG. 4B shows aberration at an image height ratio of 0.70, and FIG. High ratio 0.5
(D) shows the aberration at the image height ratio of 0.00, respectively.

FIG. 5 is a lens configuration diagram showing a second embodiment of the close-up lens of the present invention.

6 is an aberration diagram of the close-up lens of FIG. 5,
(A) shows spherical aberration, (B) shows astigmatism, and (C) shows distortion.

FIGS. 7A and 7B are lateral aberration diagrams of the close-up lens of FIG. 5, wherein FIG. 7A shows aberration at an image height ratio of 1.00, FIG. 7B shows aberration at an image height ratio of 0.70, and FIG. High ratio 0.5
(D) shows the aberration at the image height ratio of 0.00, respectively.

FIG. 8 is a lens configuration diagram showing a third embodiment of the close-up lens of the present invention.

9 is an aberration diagram of the close-up lens of FIG. 8,
(A) shows spherical aberration, (B) shows astigmatism, and (C) shows distortion.

10A and 10B are lateral aberration diagrams of the close-up lens of FIG. 8, in which FIG. 10A shows aberration at an image height ratio of 1.00, FIG. 10B shows aberration at an image height ratio of 0.70, and FIG. High ratio 0.5
(D) shows the aberration at the image height ratio of 0.00, respectively.

FIG. 11 is a lens configuration diagram showing a fourth embodiment of the close-up lens of the present invention.

12A and 12B are aberration diagrams of the close-up lens of FIG. 11, in which FIG. 12A shows spherical aberration, FIG. 12B shows astigmatism, and FIG.
Represents distortion.

13A and 13B are lateral aberration diagrams of the close-up lens of FIG. 11, in which FIG. 13A shows aberration at an image height ratio of 1.00, and FIG.
Represents aberration at an image height ratio of 0.70, and FIG.
5, (D) represents the aberration at an image height ratio of 0.00.

FIG. 14 is a lens configuration diagram showing a fifth embodiment of the close-up lens of the present invention.

15A and 15B are aberration diagrams of the close-up lens of FIG. 14, in which FIG. 15A shows spherical aberration, FIG. 15B shows astigmatism, and FIG.
Represents distortion.

16A and 16B are lateral aberration diagrams of the close-up lens of FIG. 14, wherein FIG. 16A shows aberration at an image height ratio of 1.00, and FIG.
Represents aberration at an image height ratio of 0.70, and FIG.
5, (D) represents the aberration at an image height ratio of 0.00.

FIG. 17 is a lens configuration diagram showing a sixth embodiment of the close-up lens of the present invention.

18A and 18B are aberration diagrams of the close-up lens of FIG. 17, wherein FIG. 18A shows spherical aberration, FIG. 18B shows astigmatism, and FIG.
Represents distortion.

19A and 19B are lateral aberration diagrams of the close-up lens of FIG. 17; FIG. 19A illustrates aberration at an image height ratio of 1.00, and FIG.
Represents aberration at an image height ratio of 0.70, and FIG.
5, (D) represents the aberration at an image height ratio of 0.00.

FIG. 20 is a lens configuration diagram showing a seventh embodiment of the close-up lens of the present invention.

21A and 21B are aberration diagrams of the close-up lens of FIG. 20, in which FIG. 21A shows spherical aberration, FIG. 21B shows astigmatism, and FIG.
Represents distortion.

22A and 22B are lateral aberration diagrams of the close-up lens of FIG. 20. FIG. 22A illustrates aberration at an image height ratio of 1.00, and FIG.
Represents aberration at an image height ratio of 0.70, and FIG.
5, (D) represents the aberration at an image height ratio of 0.00.

[Explanation of symbols]

 2 Film unit with lens 10 Photographing lens 19 Aperture 20 Close-up lens 21 First lens group 22 Second lens group 40 Close-up adapter

Claims (2)

[Claims] 1. A close-up lens which is built in a fixed focus camera and is used by being attached to a front surface of a photographing lens comprising a quasi-wide angle lens, comprising: a first lens group comprising one negative lens in order from the object side; And a second lens group consisting of one positive lens. The focal length of the first lens group is f1, the focal length of the second lens group is f2, and the combined focal length of the entire close-up lens is f. The photographing magnification of the entire optical system including the lens is β, the diagonal length of the exposure screen by the entire optical system including the photographing lens is d, and the distance from the image side lens surface of the positive lens to the entrance pupil position of the photographing lens is Re. A close-up lens characterized by satisfying the following conditional expressions: −2.0 ≦ f1 / f2 ≦ −0.5 d / 3f ≦ β ≦ d / f5 ≦ Re ≦ 30 2. A close-up lens which is built in a fixed focus camera and is used by being attached to a front surface of a photographing lens comprising a quasi-wide angle lens, comprising: a first lens group comprising one negative lens in order from the object side; A plurality of lenses including at least one positive lens, and a second lens group having a positive refractive power as a whole. The focal length of the first lens group is f1, and the focal length of the second lens group is f2, f is the combined focal length of the entire close-up lens, β is the photographing magnification of the entire optical system including the photographing lens, d is the diagonal length of the exposure screen by the entire optical system including the photographing lens, and d is the maximum of the second lens group. Assuming that the distance from the lens surface located on the image side to the entrance pupil position of the photographing lens is Re, −1.0 ≦ f1 / f2 ≦ −0.5 d / 3f ≦ β ≦ d / f 5 ≦ Re ≦ 30 Articles A close-up lens that satisfies the conditional expression.