JP5168533B2 - Lens barrel and optical system - Google Patents

Description

  The present invention relates to a lens barrel and an optical system.

A known method of using a single-lens reflex camera with interchangeable lenses is to mount a teleconverter (hereinafter referred to as a telecon) between the lens and the camera body and extend the focal length of the lens to shoot a large subject. (See Japanese Patent No. 3345890).
Japanese Patent No. 3345890

  An object of the present invention is to provide a lens barrel and an optical system that can reduce a focus error.

The invention of claim 1, wherein for solving the above problems, mounting a lens barrel attached to an optical device for converting a focal length at a predetermined ratio, an optical system for capturing an image, said optical device A lens barrel having a mount portion capable of holding the optical system, an aperture portion for adjusting the brightness of the image, and an image when the aperture amount of the aperture portion is changed using the optical system A first design value for the distance that the surface moves, a first measurement value for the distance that the image plane moves when the aperture amount is changed using the optical system, the optical system, and the optical device A storage unit that stores a second design value for the distance that the image plane moves when the aperture amount is changed using a combination of the first aperture , the first design value, and the first measurement value; use the second design value, and information related to the magnification of the optical system Te, and characterized in that it comprises an arithmetic unit for image plane calculates the information relating to distance traveled when said using a combination of optical system and said optical device to change the amount of squeezing said.

A second aspect of the present invention is the lens barrel according to the first aspect, wherein the photographing distance by the optical system is variable to infinity, an intermediate distance and a close distance, and the storage unit has a plurality of photographing distances. said first design value and the second design value for, stores the first measured value for one photographing distance, the calculating unit, the first design values according to the shooting distance and the second The aperture value is changed using a combination of the optical system and the optical device, using two design values, the first measurement value for one shooting distance , and information on the magnification of the optical device. Information on the distance that the image plane moves is calculated .
The invention according to claim 3, a lens barrel according to claim 1 or 2, wherein the lens barrel, each of the plurality of the optical device having different magnification is attachable, wherein the storage unit, Each of the second design values when the aperture amount is changed using a combination of the optical system and the plurality of optical devices is stored, and the calculation unit is configured to attach the lens barrel. Information relating to the magnification of the optical device and the second design value are read out and the calculation is performed.

A fourth aspect of the present invention is the lens barrel according to any one of the first to third aspects, wherein the first design value is a predetermined value from the opening of the aperture portion using the optical system . This is a design value for the distance that the image plane moves when the aperture is changed, and the first measurement value is obtained when the aperture is changed from the open position to the predetermined aperture using the optical system. Measured when the image plane moves, and the second design value is obtained when the diaphragm unit is changed from the open position to the predetermined diaphragm amount using a combination of the optical system and the optical device. This is a design value for the distance that the image plane moves.

The invention of claim 5 is a lens barrel of any one of claims 1 to 4, characterized in that attached to the optical device is a teleconverter.

A sixth aspect of the present invention is the lens barrel according to any one of the first to fourth aspects, wherein the first design value is X, the first measured value is A, and the optical device When the information regarding the magnification is M, the second design value is Y, and the correction amount of the image plane when the optical device is attached to the mount portion is Y ′, the following expression 1 is satisfied. And
(Y + (X−A) × M ² ) ≦ Y ′ ≦ (Y + (X−A) × M ² ) ² Formula 1

The invention described in claim 7 is the lens barrel described in claim 6 , wherein the correction amount Y ′ satisfies the following expression (2).
Y ′ = Y + (X−A) × M ²
Formula 2

The invention according to claim 8 is an optical system comprising the lens barrel according to any one of claims 1 to 7 .

  According to the present invention, the focus error can be reduced.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings.

  FIG. 1 is a diagram for explaining the configuration of an optical system having a lens barrel according to an embodiment of the present invention. FIG. 2 is a diagram illustrating a configuration in which, when only a lens is used, for example, opening to F8 (predetermined aperture amount). FIG. 3 is a diagram showing the best image plane position when changed, and FIG. 3 shows the best image plane position when the diaphragm unit is changed from full open to F8 (predetermined aperture amount) when a teleconversion lens is combined with the lens. FIG.

  In FIG. 2, the solid line indicates the light beam when opened, and the dotted line and the two-dot chain line indicate the light beam when focused to F8. P1, P2 and P3 respectively indicate the focus position when opened, the position when narrowed to F8 (design value), and the position when narrowed to actual F8 (measured value).

  In FIG. 3, a solid line and a two-dot chain line indicate the light beam when opened and the light beam when focused to F8, respectively. P4 and P5 respectively indicate the focus position at the time of opening and the position (design value) when it is narrowed down to F8.

  As shown in FIG. 1, the optical system includes a camera body 1, a lens barrel (lens barrel) 3, and a teleconverter (optical device) 6.

  A focus detection device 2 and a conversion device 9 are accommodated in the camera body 1. The focus detection device 2 detects the shift amount of the image plane position. The conversion device 9 is connected to the focus detection device 2 and a CPU (arithmetic unit) 10 to be described later, and based on a correction amount Y ′ that is input information from the CPU 10, the shift amount of the image plane position detected by the focus detection device 2. Is converted into an accurate image plane displacement amount.

  The teleconverter 6 is disposed between the camera body 1 and the lens barrel 3. The teleconverter 6 accommodates a teleconversion lens group 7 and a first information storage device 8. The first information storage device 8 stores magnification information M of the teleconverter 6.

  A lens group (optical system) 4 is accommodated in the lens barrel 3. The lens group 4 is held by the lens barrel 11. The lens barrel 11 is attached to the teleconverter 6 via the mount portion 13. In the lens barrel 3, a diaphragm unit 12, a CPU (calculation unit) 10, and a second information storage device 5 are accommodated. The second information storage device 5 includes information X on the design image plane position of the lens group 4, information A on the measurement image plane position of the lens group 4, and a design image plane when the lens group 4 and the teleconverter 6 are combined. Information Y on the position is stored.

The CPU 10 is connected to the first information storage device 8 and the second information storage device 5. When the teleconverter 6 is combined with the lens barrel 3, the CPU 10 reads information stored in the first information storage device 8 and the second information storage device 5, and an image plane when the teleconverter 6 is attached. The position correction amount Y ′ is calculated. The correction amount Y ′ is approximately obtained from the two equations.
Y ′ = Y + (X−A) × M ² 2 formulas

  The CPU 10 inputs information M relating to the magnification of the teleconverter 6 from the first information storage device 8, and information relating to the design image plane position of the lens group 4 from the second information storage device 5 (F0F8 design value in FIG. 4) X. , Information A regarding the measured image plane position of the lens group 4 and information Y regarding the design image plane position when the lens group 4 and the teleconverter 6 are combined are input, the correction amount Y ′ is calculated, and output to the converter 9. To do.

  The conversion device 9 corrects the shift amount of the image plane position detected by the focus detection device 2 based on the correction amount Y ′ that is input information from the CPU 10 and converts it to an accurate image plane shift amount.

  Note that the information X related to the design image plane position of the lens group 4 is a design value for the distance that the image plane position of the lens group 4 moves when the diaphragm unit 12 is changed from open to F8 (predetermined aperture amount). is there.

  The information A related to the measured image plane position of the lens group 4 is a measured value of the distance by which the image plane position moves by the lens group 4 when the diaphragm unit 12 is changed from open to F8 (predetermined aperture amount). is there.

  Further, the information Y on the design image plane position when the lens group 4 and the teleconverter 6 are combined is an optical system in which the lens group 4 and the teleconverter 6 are combined when the aperture section 12 is changed from open to F8. Is a design value for the distance by which the image plane position moves.

  FIG. 4 shows an infinite distance (d0) when the lens is a single lens (without the telecon), when the 1.4 × telecon is mounted, when the 1.7 × telecon is mounted, and when the 2.0 × telecon is mounted. ) To F0F8 design value when changing from close range (dn) to the close distance (dn) and correction value when F0F8 correction is made, FIG. As a comparative example, the F0F8 design value when changing from infinity (d0) to the closest distance (dn) when the 7X telecon is installed and the F0F8 correction is not applied FIG.

  In FIG. 4, the left figure shows the F0F8 design value, and the right figure shows the F0F8 correction. In FIG. 5, the left diagram shows the F0F8 design value, and the right diagram shows when F0F8 is corrected and when it is not corrected. 4 and 5, d0 to dn each indicate a distance to the subject. d0 indicates an infinite distance, dn indicates a close distance, and d1, d2,... indicate an intermediate position between d0 and dn.

  Further, 1.4, 1.7 and 2.0 indicate the magnification (M) of the teleconverter 6, respectively.

  X0 to Xn are design values for the distance by which the image plane position is moved by the lens group 4 when the diaphragm 12 is changed from full open to F8 without mounting the teleconverter 6, and Y0 to Yn are 1.4 times telephoto. Design value for the distance that the image plane position is moved by the lens group 4 when the converter 6 is mounted and the aperture section 12 is changed from open to F8, Z0 to Zn are mounted with a 1.7x teleconverter, Design value for the distance that the image plane position is moved by the lens group 4 when the portion 12 is changed from open to F8, W0 to Wn are 2.0 times teleconverter mounted, and the aperture 12 is opened to F8 This is a design value for the distance by which the image plane position by the lens group 4 moves when changed.

  As can be seen from FIGS. 4 and 5, in the case of a single lens, F0F8 correction is performed by adding an offset amount B (= X0−A).

In FIG. 4, 1.4 ^ ² , 1.7 ^ 2 and 2.0 ^ 2 indicate 1.4 ² , 1.7 ² and 2.0 ² , respectively.

  The design value when the teleconverter 6 is mounted can be brought close to the measured value by the correction amount Y ′ obtained by the above two formulas. In the comparative example, since the correction is not performed when the teleconverter 6 is mounted, a deviation between the design value and the measurement value occurs.

  According to this embodiment, when the teleconverter 6 is mounted, the design value can be brought close to the measured value, so that the focus shift can be reduced. Further, since the correction amount is obtained by calculation, it is not necessary to store all the correction amounts for the combination of the lens group 4 and the teleconversion lens group 7, so that an information storage device having a small storage capacity can be used. Manufacturing costs can be reduced. Furthermore, since the CPU 10 is provided in the lens barrel 3, it is possible to easily cope with a case where the plurality of teleconverters 6 are used while being replaced.

The correction amount Y ′ is not limited to the value obtained by Equation 2 as long as it satisfies the following Equation 1.
(Y + (X−A) × M ² ) ≦ Y ′ ≦ (Y + (X−A) × M ² ) ² Formula 1

  In the above-described embodiment, the aperture amount has been described using the opening and F8. However, the present invention is not limited to this.

FIG. 1 is a diagram illustrating the configuration of an optical system having a lens barrel according to an embodiment of the present invention. FIG. 2 is a diagram showing the best image plane position when the diaphragm unit is changed from full open to F8 (predetermined diaphragm amount) when only the lens is used. FIG. 3 is a diagram showing the best image plane position when the aperture is changed from full open to F8 (predetermined aperture amount) when a teleconversion lens is combined with the lens. Figure 4 shows the change from infinity (d0) to the closest distance (dn) when the lens is a single lens, when the 1.4x telecon is installed, when the 1.7x telecon is installed, and when the 2.0x telecon is installed. It is a figure which shows the F0F8 design value at the time of making it and the correction value when F0F8 correction | amendment is carried out. Figure 5 shows the change from infinity (d0) to the closest distance (dn) when the lens is a single lens, when the 1.4x telecon is installed, when the 1.7x telecon is installed, and when the 2.0x telecon is installed. It is the figure which showed the F0F8 design value when letting it be, and the value when not performing F0F8 correction as a comparative example.

Explanation of symbols

  3: lens barrel (lens barrel), 4: lens group (optical system), 6: teleconverter (optical device), 10: CPU (arithmetic unit), 11: barrel, 12: aperture unit, 13: mount unit .

Claims (8)

A lens barrel attached to an optical device that converts a focal length into a predetermined magnification;
An optical system for capturing an image;
A lens barrel, wherein a mount portion which can be attached to an optical device, for holding said optical system,
A diaphragm for adjusting the brightness of the image;
A first design value for the distance that the image plane moves when the aperture amount of the aperture section is changed using the optical system, and an image when the aperture amount is changed using the optical system A first measurement value for the distance that the surface moves, and a second design value for the distance that the image surface moves when the aperture amount is changed using a combination of the optical system and the optical device. A storage unit for storing;
Wherein a first design value, the a first measurement, the second design value, by using the information about the magnification of the optical system, the aperture amount the used in combination with the optical system and the optical device A calculation unit that calculates information on the distance that the image plane moves when changing
A lens barrel characterized by comprising: The lens barrel according to claim 1,
The shooting distance by the optical system is variable at infinity, intermediate distance and close distance,
Said storage unit stores said the first design value and the second design values for a plurality of photographing distance, the first measurement value for one photographing distance,
The calculation unit uses the first design value and the second design value according to the shooting distance, the first measurement value for one shooting distance , and information about the magnification of the optical device, and A lens barrel characterized in that an optical system and the optical device are used in combination to calculate information relating to a distance that an image plane moves when the aperture amount is changed . The lens barrel according to claim 1 or 2,
The lens barrel, each of the plurality of the optical device having different magnification can be mounted,
The storage unit stores the respective second design value when the optical system and a plurality of optical devices was used in combination of varying the amount of squeezing said,
The lens barrel is characterized in that the calculation unit reads the information about the magnification of the optical device to which the lens barrel is attached and the second design value and performs the calculation. The lens barrel according to any one of claims 1 to 3,
The first design value is a design value for a distance that the image plane moves when the diaphragm unit is changed from the open position to a predetermined diaphragm amount using the optical system ,
The first measurement value is a measurement value for a distance that the image plane moves when the diaphragm unit is changed from the open position to the predetermined diaphragm amount using the optical system ,
The second design value is a design value for a distance that the image plane moves when the diaphragm unit is changed from a fully open position to a predetermined diaphragm amount by using the optical system and the optical device in combination. A lens barrel characterized by The lens barrel according to any one of claims 1 to 4,
A lens barrel attached to the optical device which is a teleconverter. The lens barrel according to any one of claims 1 to 4,
The first design value is X, the first measurement value is A, the information about the magnification of the optical device is M, the second design value is Y, and the optical device is attached to the mount portion. A lens barrel characterized by satisfying the following expression 1 where Y ′ is the correction amount of the image plane at that time.
(Y + (X−A) × M2) ≦ Y ′ ≦ (Y + (X−A) × M2) 2 Equation 1 The lens barrel according to claim 6, wherein
The correction amount Y ′ satisfies the following expression (2).
Y ′ = Y + (X−A) × M 2
Formula 2   An optical system comprising the lens barrel according to any one of claims 1 to 7.

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