JP2000292696A - Image pickup device and attachment lens - Google Patents

Abstract

PROBLEM TO BE SOLVED: To effectively avoid a problem of causing an eclipse, and to variously change a focal distance by a small number of attachment lenses by arranging first/second attachment lenses selectively arrangeable in a main body lens, and setting the main body side first attachment lens at this time to power higher than the second attachment lens. SOLUTION: A digital camera 1 can change a focal distance by a main body lens 2 by selectively installing an attachment lens 4 or 5 by a mount 3 when necessary. Here, while the attachment lens 4 is, for example, 1.6 times in power, the attachment lens 5 is set to 1.25 times in power. Thus, while a focal distance of an optical system can be changed to 1.6 times and 1.25 times by respectively installing the attachment lenses 4 and 5, the focal distance can be changed to about two times by installing the attachment lens 5 in front of the attachment lens 4.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] 1. Field of the Invention [0002] The present invention relates to an image pickup apparatus and an attachment lens.
It can be applied to the attachment lens. The present invention provides first and second lenses that can be selectively arranged on a main body lens.
The attachment lens can be combined and arranged, and at this time, the first attachment lens on the main body side is
By setting the magnification to be higher than that of the second attachment lens, it is possible to effectively avoid problems such as the occurrence of eccentricity, and to change the focal length of the optical system with a small number of attachment lenses. .

[0002]

2. Description of the Related Art Conventionally, a digital camera has been configured to electrically record an imaging result obtained from a solid-state imaging device, and is used for capturing an image into a personal computer. In such a digital camera, an optical system is formed by a lens having a fixed focal length so as to improve portability, and further, it can be applied to a relatively wide range of various shootings.
The optical system is configured by a wide-angle lens having a focal length of about 28 to 40 [mm] (35 [mm] conversion).

[0003] In such a digital camera, an attachment lens is attached to the front of the lens.
The focal length of the optical system can be changed. That is, for example, in a digital camera having an optical system having a focal length of 40 [mm] (35 [mm] conversion), by attaching an attachment lens with a magnification of 1.5 times, the focal length of the optical system can be increased to 60 [mm] (35). [Mm]
Conversion).

[0004]

By the way, in such a configuration in which the focal length is changed by attaching the attachment lens, it is necessary to prepare an attachment lens for each desired focal length.

In this case, if the configuration is such that the attachment lenses can be mounted in combination, the focal length of the optical system can be reduced with a smaller number of attachment lenses as compared with the case where the attachment lenses are simply replaced to change the focal length of the optical system. Can be variously changed.

However, simply changing the focal length by simply attaching an attachment lens or combining a plurality of lenses increases the size of the lens on the object side and causes blurring. In some cases, it is difficult to obtain practically usable characteristics due to an increase in aberration.

SUMMARY OF THE INVENTION The present invention has been made in view of the above points, and an imaging method capable of effectively changing the focal length of an optical system with a small number of attachment lenses while effectively avoiding problems such as the occurrence of blurring. A device and an attachment lens are proposed.

[0008]

According to a first aspect of the present invention, there is provided an imaging apparatus in which a first or second attachment lens can be detachably disposed on a front surface of a main body lens. The second attachment lens can be detachably held on the object side of the first attachment lens disposed on the front surface of the main body lens, and the first attachment lens is disposed on the object side of the main body lens. A second attachment lens is disposed on the front surface of the first attachment lens, and the focal length of the optical system is changed from the focal length of the main body lens by the magnification of the first and second attachment lenses. In comparison, the first attachment lens has a high magnification.

According to the structure of the first aspect of the present invention, the first or second attachment lens is selectively attached to the front surface of the main body lens, and the magnification is adjusted according to the magnification of the first or second attachment lens, respectively. The focal length can be obtained, and the first and second attachment lenses are sequentially arranged on the front surface of the main body lens, and the focal length according to the magnification of the first and second attachment lenses can be obtained. Thus, the focal length of the optical system can be variously changed by a small attachment lens. At this time, if the first attachment lens is made to have a higher magnification than the second attachment lens, the lens diameter of the second attachment lens can be reduced as compared to the opposite case. Generation of division can be effectively avoided, and furthermore, image distortion can be reduced.

[0010] According to the second aspect of the present invention, the first aspect is provided.
In the configuration of the first attachment lens, the position of the aperture stop is located on the image plane side of the lens group, and when the first attachment lens is disposed in front of the main body lens, the aperture stop substantially matches the entrance pupil of the main body lens. In the attachment lens 2, the aperture stop is located closer to the image plane than the lens group, and when it is arranged in front of the main lens, the aperture stop almost matches the entrance pupil of the main lens, and is closer to the object side than the main lens. When arranged on the object side of the arranged first attachment lens, the aperture stop is made to substantially coincide with the entrance pupil of the main lens.

According to the configuration of the invention according to claim 2, the first
When the second attachment lens is arranged on the object side of the main body lens, the second attachment lens is arranged on the front side of the first attachment lens, and when the first attachment lens is arranged on the front side of the first attachment lens.
In any case where the attachment lens is disposed in front of the main body lens, the aperture stop of these attachment lenses can be substantially matched with the entrance pupil of the main body lens, thereby preventing shaking. Can be.

According to the third aspect of the present invention, there is provided the first aspect.
Alternatively, in the configuration of claim 2, the second attachment lens is configured such that at least a lens on the object side is an aspherical lens.

According to the configuration of the invention according to claim 3, the first aspect
By disposing the second attachment lens having a larger diameter than that of the first attachment lens, it is possible to reduce the occurrence of each aberration of the luminous flux incident from the periphery of the second attachment lens.

According to a fourth aspect of the present invention, in the configuration of the first, second or third aspect, the first and second attachment lenses have a first refractive power having a positive refractive power.
The lens group and the second lens group having negative refractive power are arranged sequentially from the object side.

According to the fourth aspect of the present invention, the focal length can be changed with a simple lens configuration to prevent shaking and reduce the occurrence of image distortion.

According to a fifth aspect of the present invention, there is provided an attachment lens which is detachably mounted on a front surface of a main body lens of the imaging device and changes a focal length of an optical system of the imaging device from a focal length of the main body lens. And a holding mechanism for detachably holding another attachment lens that can be arranged on the front surface of the main body lens, and has a higher magnification than the other attachment lens.

According to the fifth aspect of the present invention, the attachment lens or the second attachment lens is selectively attached to the front surface of the main body lens, and the focal length of the optical system in the imaging device is set to each attachment lens. The focal length can be changed according to the magnification, and the attachment lens and the second attachment lens are sequentially arranged in front of the main body lens, and the focal length according to the magnification between the attachment lens and the second attachment lens Thus, the focal length of the imaging device can be variously changed by a small attachment lens. At this time, if the magnification is higher than that of the second attachment lens, the lens diameter of the second attachment lens can be reduced as compared with the opposite case, and the occurrence of the division can be effectively reduced. This can be avoided, and furthermore, image distortion can be reduced.

According to the invention of claim 6, in claim 5,
In the above configuration, the position of the aperture stop is located closer to the image plane side than the lens group, and when the aperture stop is arranged on the front surface of the main body lens, the aperture stop substantially matches the entrance pupil of the main body lens.

According to the configuration of the invention according to claim 6, the aperture stop of the attachment lens and the entrance pupil of the main lens can be made substantially coincident with each other, thereby preventing shaking.

In the invention of claim 7, claim 5
Alternatively, in the configuration according to claim 6, the first member having a positive refractive power is provided.
The lens group and the second lens group having negative refractive power are arranged sequentially from the object side.

According to the seventh aspect of the present invention, it is possible to change the focal length by using a simple lens configuration to prevent eclipse and to reduce the occurrence of image distortion.

[0022]

Embodiments of the present invention will be described below in detail with reference to the drawings. Note that some parts of the drawings are exaggerated for ease of understanding.

(1) First Embodiment (1-1) Configuration of First Embodiment FIG. 1 is a perspective view showing a digital camera according to a first embodiment of the present invention. This digital camera 1
The main lens 2 arranged on the front side is constituted by a relatively short-focus wide-angle lens, and a desired subject can be imaged using the main lens 2.

In the digital camera 1, a circular concave portion is formed on the front surface, the front surface of the main body lens 2 is formed to protrude from the center of the concave portion, and a thread is formed on the wall surface of the concave portion. It has been done. In the digital camera 1, a mount 3 is formed by a thread formed on the wall, and the mount lens 3 allows the attachment lens 4 or 5 to be selectively attached as needed, so that the focal length of the main body lens 2 can be changed. Has been made.

That is, the attachment lenses 4 and 5
Each has a cylindrical convex portion 6 formed on the back side, and a thread is formed on an outer peripheral wall surface of the convex portion 6. The attachment lenses 4 and 5 are mounted by the convex portions 6, and can be attached to the digital camera 1 by screwing the convex portions into the mount 3 of the digital camera 1.

Such attachment lenses 4 and 5
, The attachment lens 4 has a cylindrical projection 7 formed on the front side. The cylindrical convex portion 7 has an inner wall surface formed in the same shape as the mount 3 of the digital camera 1, whereby the attachment lens 4 is
The attachment lens 5 can be further attached to the front surface as needed.

Here, the attachment lens 4 has a magnification of 1.6 times, whereas the attachment lens 5 has a magnification of 1.6 times.
The magnification is 1.25 times. Thus, in the digital camera 1, the attachment lenses 4 and 5 are attached to increase the focal length of the optical system by 1.6 times and 1.25, respectively.
By contrast, while the attachment lens 4 is attached and the attachment lens 5 is further attached to the front surface (object side) of the attachment lens 4, the focal length of the optical system can be changed about twice. I have.

FIG. 2 is a sectional view showing the lens structure of the high-magnification side attachment lens 4. As shown in FIG. The attachment lens 4 includes, from the object side, a first lens group having a positive refractive power and a second lens group having a negative refractive power, thereby forming an afocal optical system as a whole, The focal length of the digital camera 1 can be changed by reducing the image distortion with a simple configuration.

In the attachment lens 4, one meniscus lens 4A is assigned to the first lens group, and one meniscus lens 4B is assigned to the second lens group. The meniscus lenses 4A and 4B constituting the first and second lens groups are plastic lenses formed by injection-molding a predetermined transparent resin material. As the resin material, the first meniscus lens 4A has an Abbey lens. An acrylic resin having a number of 57 is applied, and the Abbe number is 30 for the second meniscus lens 4B.
Is applied. As a result, the attachment lens 4 can be achromatized as a whole by utilizing the difference in dispersion of these resins.

The material of the meniscus lens 4A is, for example, amorphous polyolefin as a material having an Abbe number of 50 or more instead of the acrylic resin, and the material of the meniscus lens 4B is a material having an Abbe number of 49 instead of the polycarbonate resin. As the following materials, for example, polystyrene, polyethylene terephthalate and the like can be used. A meniscus lens 5 described later
The same applies to A and 5B.

Further, in the attachment lens 4, the position of the aperture stop is located on the rear side of the image from the lens group.
This aperture stop is located at a position substantially coincident with the entrance pupil of the main lens 2 when arranged on the front surface of the lens.
Thus, the attachment lens 4 is attached to the digital camera 1 so that the occurrence of shaking can be effectively avoided.

Further, in the attachment lens 4, while the concave lens surfaces of the meniscus lenses 4A and 4B are formed by spherical surfaces, the convex lens surfaces of the meniscus lenses 4A and 4B are formed by aspheric surfaces, thereby preventing the occurrence of various aberrations. It has been made possible. FIG. 3 is a diagram showing the structure of the attachment lens 4 and FIG.
Each aberration when attached to the lens is shown. In FIG. 3, parameters r, k and a are variables indicating the lens surface shape expressed by the following equation, parameter h is the height from the optical axis, and Z is the optical axis direction of the lens surface according to the variable h. Indicates the position of. FIG. 4 shows a characteristic in which the main lens 2 is an ideal lens. In each of these aberration diagrams, the vertical axis represents the image height and the ray height.

[0033]

(Equation 1)

FIG. 5 is a sectional view showing the lens structure of the attachment lens 5 on the low magnification side. FIG.
7 and 8 are a chart and a characteristic curve diagram showing the attachment lens 5 in comparison with FIGS. The attachment lens 5, like the attachment lens 4, is composed of a first lens group having a positive refractive power and a second lens group having a negative refractive power, thereby forming an afocal optical system as a whole. With a simple configuration, image distortion can be reduced and the focal length of the digital camera 1 can be changed in various ways.

The attachment lens 5 has the first
One meniscus lens 5A is assigned to the lens group, and one meniscus lens 5B is assigned to the second lens group. Each of the first and second meniscus lenses 5A and 5B is a plastic lens obtained by injection-molding an acrylic resin and a polycarbonate resin, respectively, so that achromatism can be achieved.

Further, in the attachment lens 5, the position of the aperture stop is located closer to the object side than the lens group,
This aperture stop is located at a position substantially coincident with the entrance pupil of the main lens 2 when arranged on the front surface of the lens.
Further, the attachment lens 5 has a larger lens diameter than the lens diameter sufficient to set the aperture pupil as described above, and as shown in FIG. In this case, the position of the aperture stop is set at the entrance pupil of the attachment lens 4 (in this case, a position almost coincident with the entrance pupil of the main lens 2).
Has been made to almost match. Thus, the attachment lens 5 can be attached to the digital camera 1 by itself, and further attached to the digital camera 1 in combination with the attachment lens 4, so that the occurrence of shaking can be effectively avoided.

Further, the attachment lens 5 has both sides of the meniscus lenses 5A and 5B formed of aspherical surfaces, whereby the attachment lens 5 is attached to the digital camera 1 by itself and further attached to the digital camera 1 in combination with the attachment lens 4, and The configuration is such that occurrence of aberration can be prevented. FIG. 9 is a diagram showing a configuration in which the attachment lens 5 is combined with the attachment lens 4 and attached to the digital camera 1, and FIG. 10 shows each aberration due to this configuration.

(1-2) Operation of First Embodiment In the above configuration, in the digital camera 1,
An image of a desired subject is formed on the imaging surface of the solid-state imaging device by the main lens 2 which is a wide-angle lens, and thus various subjects can be imaged.

In this digital camera 1, the attachment lens 4 or 5 is brought to the front of the main body lens 2, and the protrusion formed on the back of the attachment lens 4 or 5 is inserted into the mount 3 and screwed. The attachment lens 4 on the front of the body lens 2
Alternatively, it is possible to increase the focal length of the optical system by the main body lens 2 by selectively attaching 5. That is, since the attachment lenses 4 and 5 that can be attached in this manner have magnifications of 1.6 times and 1.25 times, respectively, in the digital camera 1, the focal length of the optical system by the main body lens 2 is equal to that of the attachment lenses 4 and 5. 5
The magnification is 1.6 times and 1.25 times, respectively.
This allows the digital camera 1 to shoot at various angles of view that cannot be expressed with the main lens 2 alone.

At this time, each of the attachment lenses 4 and 5 has an afocal optical system including a first lens group having a positive refractive power and a second lens group having a negative refractive power. With a simple configuration, image distortion can be reduced and the focal length of the digital camera 1 can be variously changed.

Further, since the first lens group and the second lens group are each constituted by one single lens, and furthermore, each is constituted by a plastic lens, the overall constitution is simplified. Furthermore, the overall weight is reduced.

Further, in each of the attachment lenses 4 and 5, the position of the aperture stop is located on the image plane side of the lens group, and when the aperture stop is disposed on the front surface of the main lens 2, the aperture stop is substantially the same as the entrance pupil of the main lens 2. Since the positions are coincident with each other, it is possible to effectively avoid the occurrence of the shaking by attaching the digital camera 1 to the digital camera 1.
In addition, various aberrations are reduced because the lens surface of each lens is formed by an aspheric surface as needed.

On the other hand, in the attachment lens 4, the mount 7 having the same shape as the mount 3 formed on the digital camera 1 is formed on the front surface (object side). The attachment lens 5 can be further attached to the front surface of the attachment lens 4 with. This allows the digital camera 1
In, the focal length of the optical system as a whole can be switched in four steps by two types of attachment lenses, and the focal length of the optical system can be variously changed by a small number of attachment lenses.

At this time, in the digital camera 1,
Since the attachment lens 4 on the side of the main body lens 2 has a higher magnification than the attachment lens 5, the overall shape can be reduced accordingly, and furthermore, the occurrence of various aberrations can be easily reduced, and Can be prevented.

That is, when this type of lens is combined, in the lens arranged on the object side, a light beam separated from the optical axis is condensed on the image plane as compared with the case where the lens is attached to the digital camera 1 alone. (Fig. 5
FIG. 8) in comparison with FIG. In this embodiment, in the attachment lens 5 disposed on the object side, even when the attachment lens 4 is attached to the object side in this way, the position of the aperture stop is substantially coincident with the entrance pupil of the main lens 2. By being done in
Occurrence of jolting can be effectively avoided.

However, in order to prevent shaking in this way, it is necessary to increase the lens diameter and the like as compared with the case where the lens is used alone, and it is necessary to secure the same magnification by combining two attachment lenses. In this case, it is necessary to increase the lens diameter and the like when a low-magnification lens is disposed on the main lens 2 side.

As described above, when the lens diameter is increased, the overall shape becomes larger, the overall weight increases, and it becomes difficult to correct various aberrations.
Thus, in this embodiment, the attachment lens 4 on the side of the main lens 2 is set to a high magnification, so that the overall shape can be reduced in size, and furthermore, the occurrence of various aberrations can be easily reduced and It has been made possible to prevent injuries.

Further, in this embodiment, each lens surface is formed by an aspheric surface in the attachment lens 5 as described above, so that occurrence of various aberrations can be reduced even if the lens diameter is enlarged.

(1-3) Effects of the First Embodiment According to the above configuration, the attachment lenses 4 and 5 can be combined and arranged on the main lens 2, and at this time, the attachment lens 4 on the main lens 2 side is used. Is set to a higher magnification than the attachment lens 5, it is possible to effectively avoid occurrence of blurring and the like, and to change the focal length of the optical system variously with a small number of attachment lenses.

Further, in each of the attachment lenses 4 and 5, the position of the aperture stop is positioned closer to the image plane side than the lens group, and when the aperture stop is disposed in front of the main lens 2, the aperture stop substantially matches the entrance pupil of the main lens 2. With this arrangement, when the attachment lens 5 is disposed on the attachment lens 4, the aperture stop substantially matches the entrance pupil of the main lens 2, thereby effectively avoiding the occurrence of blurring. be able to.

Further, since the lens surface of the attachment lens 5 is set to be aspherical, occurrence of various aberrations can be reduced.

The attachment lenses 4 and 5 are composed of a first lens group having a positive refractive power and a second lens group having a negative refractive power. Further, the first and second lens groups are made of plastic. By using a single lens as a lens, the occurrence of various aberrations can be reduced with a simple configuration as a whole.

(2) Second Embodiment In the second embodiment, the attachment lenses 4 and 5 are replaced by attachment lenses 14 and 15 having magnifications of 1.55 and 1.3. The magnification of the digital camera 1 is variously changed. In this embodiment, the attachment lenses 14 and 15
Except for the difference in the configuration of each lens surface, the configuration is the same as that of the attachment lenses 4 and 5 according to the first embodiment. , Overlapping description will be omitted.

FIG. 11 is a cross-sectional view showing the lens configuration of the high-magnification side attachment lens 14, FIG. 12 is a table showing the configuration of the attachment lens 14, and FIG. It is an aberration figure.

FIG. 14 is a cross-sectional view showing the lens configuration of the low-magnification side attachment lens 15, FIG. 15 is a table showing the configuration of the attachment lens 15, and FIG.
It is various aberration figures of.

FIG. 17 shows the attachment lens 1.
FIG. 18 is a cross-sectional view showing the configuration of a case where 4 and 15 are combined, and FIG. 18 is a chart showing the configuration of each lens;
FIG. 19 is a diagram of various aberrations.

According to the second embodiment, the magnification is 1.55.
The same effects as in the first embodiment can be obtained by using the double and 1.3 times attachment lenses 14 and 15.

(3) Third Embodiment In the third embodiment, in place of the attachment lenses 4 and 5 described in the first embodiment, magnifications of 1.6 and 1.25 are used. The magnification of the digital camera 1 is variously changed by certain attachment lenses 24 and 25.

FIG. 20 is a schematic diagram showing the lens configuration of the attachment lens 24 on the high magnification side. In the attachment lens 24, the first lens group includes two meniscus lenses 24A and 24B, and the second lens group includes the meniscus lens 24C.

The first attachment lens 24
Except for the configuration of the lens group and the second lens group, the configuration of the aperture stop and the like is the same as that of the attachment lens 4 according to the first embodiment. FIG. 21 is a table showing the configuration of the attachment lens 24, and FIG. 22 is a diagram showing various aberrations of the attachment lens 24.

FIG. 23 is a schematic diagram showing the lens structure of the attachment lens 25 on the low magnification side. The attachment lens 25 includes a meniscus convex lens 25A and a biconvex lens 25B having two first lens groups.
, And the second lens group is constituted by the concave lens 25C.

The attachment lens 25 is provided with these first lenses.
Except for the configuration of the lens group and the second lens group, the configuration of the aperture stop and the like is the same as that of the attachment lens 5 according to the first embodiment. FIG. 24 is a table showing the configuration of the attachment lens 24, and FIG. 25 is a diagram showing various aberrations of the attachment lens 24.

FIG. 26 shows the attachment lens 2
FIG. 27 is a schematic diagram illustrating a configuration of a case where 4 and 25 are combined, and FIG. 27 is a diagram illustrating a configuration of each lens;
FIG. 28 is a diagram of various aberrations.

According to the third embodiment, the same effects as those of the first embodiment can be obtained even if the first lens group constituting each of the attachment lenses 24 and 25 is constituted by a plurality of lenses. be able to.

Since the first lens group on the large-diameter side is composed of a plurality of lenses, the thickness of each lens constituting the first lens group can be reduced. Therefore, productivity in injection molding can be improved accordingly.

(4) Other Embodiments In the above-described embodiment, a case has been described where each lens surface is set to be an aspherical surface as necessary. However, the present invention is not limited to this. When using an attachment lens in combination, the most influential factor for the occurrence of various aberrations is the lens closest to the object, so at least applying the aspherical surface to the lens closest to the object efficiently Occurrence of aberration can be reduced.

In the above-described third embodiment,
Although the case where the first lens group is constituted by two lenses has been described, the present invention is not limited to this, and can be widely applied to the case where the first lens group and / or the second lens group is constituted by a plurality of lenses. Can be.

In the above-described embodiment, the case where two attachment lenses are used in combination has been described. However, the present invention is not limited to this, and is widely applied to the case where three or more attachment lenses are used in combination. Can be applied.

In the above embodiment, the case where the present invention is applied to a digital camera has been described.
The present invention is not limited to this, and can be widely applied to various imaging devices such as a silver halide camera using a fixed focus lens.

[0070]

As described above, according to the present invention, the first and second attachment lenses that can be selectively arranged on the main body lens can be sequentially arranged from the main body lens side. By making the attachment lens higher in magnification than the second attachment lens, it is possible to effectively avoid problems such as the occurrence of eccentricity and variously change the focal length of the optical system with a small number of attachment lenses. Can be.

[Brief description of the drawings]

FIG. 1 is a perspective view showing a digital camera according to a first embodiment of the present invention.

FIG. 2 is a sectional view showing a lens configuration of the attachment lens 4.

FIG. 3 is a table showing the lens configuration of FIG. 2;

FIG. 4 is an aberration diagram showing various aberrations of the lens of FIG. 2;

FIG. 5 is a sectional view showing a lens configuration of the attachment lens 5;

FIG. 6 is a table showing the lens configuration of FIG. 5;

FIG. 7 is an aberration diagram showing various aberrations of the lens of FIG. 5;

FIG. 8 is a cross-sectional view showing a lens configuration when attachment lenses 4 and 5 are combined.

FIG. 9 is a table showing the lens configuration of FIG. 8;

FIG. 10 is an aberration diagram showing various aberrations in the case of FIG. 8;

FIG. 11 is a sectional view showing a lens configuration of an attachment lens applied to a digital camera according to a second embodiment of the present invention.

FIG. 12 is a table showing the lens configuration of FIG. 11;

FIG. 13 is an aberration diagram showing various aberrations of the lens in FIG. 11;

FIG. 14 is a sectional view showing a lens configuration of an attachment lens 15 applied to a digital camera according to a second embodiment of the present invention.

FIG. 15 is a table showing the lens configuration of FIG. 14;

FIG. 16 is an aberration diagram showing various aberrations of the lens in FIG. 14;

FIG. 17 is a cross-sectional view showing a lens configuration when attachment lenses 14 and 15 are combined.

FIG. 18 is a table showing the lens configuration of FIG. 17;

FIG. 19 is an aberration diagram showing various aberrations in the case of FIG. 18;

FIG. 20 is a sectional view showing a lens configuration of an attachment lens 24 applied to a digital camera according to a third embodiment of the present invention.

FIG. 21 is a table showing the lens configuration of FIG. 20;

FIG. 22 is an aberration diagram showing various aberrations of the lens in FIG. 20;

FIG. 23 is a sectional view showing a lens configuration of an attachment lens 25 applied to a digital camera according to a third embodiment of the present invention.

FIG. 24 is a table showing the lens configuration of FIG. 23;

25 is an aberration diagram showing various aberrations of the lens in FIG.

FIG. 26 is a cross-sectional view showing a lens configuration when attachment lenses 24 and 25 are combined.

FIG. 27 is a table showing the lens configuration of FIG. 26;

28 is an aberration diagram showing various aberrations in the case of FIG. 26.

[Explanation of symbols]

1 ... Digital camera, 2 ... Body lens, 3 ... Mount, 4, 5, 14, 15, 24, 25 ... Attachment lens

 ──────────────────────────────────────────────────続 き Continued on the front page F term (reference) 2H087 KA01 LA30 PA02 PA03 PA04 PA06 PA17 PB02 PB03 PB04 PB06 QA02 QA06 QA12 QA14 QA17 QA21 QA22 QA25 QA26 QA37 QA39 QA41 QA45 QA46 RA05 RA12 RA13 RA35 2H105 CC

Claims (7)

[Claims] 1. An imaging apparatus in which a first or second attachment lens can be detachably mounted on a front surface of a main body lens, wherein the object side is closer to the object than the first attachment lens disposed on a front surface of the main body lens. Wherein the second attachment lens can be detachably held, and the first attachment lens is arranged on the front surface of the main body lens, and the second attachment is closer to the object side than the first attachment lens. A lens is disposed, and the focal length of the optical system is changed from the focal length of the main body lens by the magnification of the first and second attachment lenses. The first focal length is compared with the second attachment lens. An imaging device, wherein the attachment lens has a high magnification. 2. The first attachment lens, wherein the position of the aperture stop is located on the image plane side of the lens group, and when the first stop lens is disposed in front of the main body lens, the aperture stop is positioned between the entrance pupil of the main body lens and The second attachment lens substantially coincides with the second attachment lens, wherein the position of the aperture stop is located closer to the image plane side than the lens group, and when the second stop lens is disposed on the front surface of the main body lens, the aperture stop is substantially equal to the entrance pupil of the main body lens. The aperture stop substantially coincides with an entrance pupil of the main lens when the first aperture lens is disposed closer to the object side than the first attachment lens disposed in front of the main lens. Imaging device. 3. The imaging apparatus according to claim 1, wherein at least the lens on the object side of the second attachment lens is an aspherical lens. 4. The first and second attachment lenses are characterized in that a first lens group having a positive refractive power and a second lens group having a negative refractive power are sequentially arranged from the object side. The imaging device according to claim 1, 2, or 3. 5. An attachment lens which is detachably disposed on a front surface of a main body lens of the imaging device and changes a focal length of an optical system of the imaging device from a focal length of the main body lens. An attachment lens having a holding mechanism for detachably holding another attachment lens that can be arranged on the front side on an object side, and having a higher magnification than the other attachment lens. 6. The apparatus according to claim 1, wherein the position of the aperture stop is located closer to the image plane than the lens group, and the aperture stop substantially coincides with the entrance pupil of the main body lens when the aperture stop is disposed in front of the main body lens. An attachment lens according to claim 5. 7. The apparatus according to claim 5, wherein a first lens group having a positive refractive power and a second lens group having a negative refractive power are sequentially arranged from the object side. Attachment lens.