WO2014132584A1 - リアコンバージョンレンズ - Google Patents
リアコンバージョンレンズ Download PDFInfo
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- WO2014132584A1 WO2014132584A1 PCT/JP2014/000764 JP2014000764W WO2014132584A1 WO 2014132584 A1 WO2014132584 A1 WO 2014132584A1 JP 2014000764 W JP2014000764 W JP 2014000764W WO 2014132584 A1 WO2014132584 A1 WO 2014132584A1
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- lens
- rear conversion
- image
- subject side
- camera
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- G—PHYSICS
- G02—OPTICS
- G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
- G02B13/00—Optical objectives specially designed for the purposes specified below
- G02B13/001—Miniaturised objectives for electronic devices, e.g. portable telephones, webcams, PDAs, small digital cameras
- G02B13/0015—Miniaturised objectives for electronic devices, e.g. portable telephones, webcams, PDAs, small digital cameras characterised by the lens design
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- G—PHYSICS
- G02—OPTICS
- G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
- G02B15/00—Optical objectives with means for varying the magnification
- G02B15/02—Optical objectives with means for varying the magnification by changing, adding, or subtracting a part of the objective, e.g. convertible objective
- G02B15/10—Optical objectives with means for varying the magnification by changing, adding, or subtracting a part of the objective, e.g. convertible objective by adding a part, e.g. close-up attachment
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- G—PHYSICS
- G02—OPTICS
- G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
- G02B15/00—Optical objectives with means for varying the magnification
- G02B15/02—Optical objectives with means for varying the magnification by changing, adding, or subtracting a part of the objective, e.g. convertible objective
- G02B15/04—Optical objectives with means for varying the magnification by changing, adding, or subtracting a part of the objective, e.g. convertible objective by changing a part
- G02B15/08—Optical objectives with means for varying the magnification by changing, adding, or subtracting a part of the objective, e.g. convertible objective by changing a part by changing the rear part
Definitions
- the present technology relates to a rear conversion lens, and more particularly to a rear conversion lens used for using a photographing lens for a three-plate camera for a single-plate color camera.
- some 2/3 inch format photographing lenses are designed on the assumption that they are used with a three-plate camera using a color separation prism.
- this photographic lens is used in a single-plate color camera, the premise of the color separation prism is eliminated, and a large amount of spherical aberration is generated. Therefore, it is difficult to use in combination.
- the object of the present technology is to use a combination of a photographic lens for a three-plate camera, which is designed on the assumption that it is used in combination with a color separation prism, and a single-plate color camera. It is an object of the present invention to provide a rear conversion lens that makes it possible.
- a rear conversion lens includes two opposite end portions, a housing having a light transmission port at each of the end portions, and three first ends.
- a housing having a light transmission port at each of the end portions, and three first ends.
- a single-plate color camera having a first imaging portion and a second imaging device having an imaging surface wider than the imaging surface of the first imaging device of the three-plate camera, and the other end of the housing
- a second connecting portion for detachably connecting the lens, a first lens group having a negative composite focal length, a second lens group for correcting spherical aberration, and a third lens group having an imaging function
- An optical system arranged in order from the subject side in the housing; Comprising.
- the rear conversion lens can be reduced in size by combining with a three-lens camera photographing lens whose image side is telecentric.
- the first lens group includes a first three-piece cemented lens, and the second lens group is formed from the subject side.
- it may be constituted by a concave lens, a convex lens, and a second three-lens bonded lens, and the third lens group may be constituted by a convex lens.
- the rear conversion lens according to an embodiment of the present technology may be configured such that the combined focal length of the second three-lens bonded lens and the third lens group is positive.
- the rear conversion lens can be reduced in size in combination with a three-plate camera photographing lens whose image side is telecentric. I can do it.
- the first three-piece cemented lens and the second three-piece cemented lens satisfy the following conditional expression (1). It may be configured. ⁇ 3.0 ⁇ (f2G) / (f1G) ⁇ 1.2 (1)
- f1G is the combined focal length of the first three-lens bonded lens
- f2G is the combined focal length of the second three-lens bonded lens.
- the composite focal length of the first three-lens cemented lens and the synthetic focal length of the second three-lens cemented lens are determined so as to satisfy the conditional expression (1), so that both the sagittal plane and the meridional plane Astigmatism is within the practical range.
- the first three-piece cemented lens may be configured to satisfy the following conditional expression (2).
- n1G1>n1G3> n1G2 (2)
- n1G1 is the refractive index of the first lens from the subject side of the first three-piece lens
- n1G2 is the refractive index of the second lens from the subject side of the first three-piece lens
- n1G3 is the refractive index of the third lens from the subject side of the first three-sheet-bonded lens.
- the refractive index of each lens of the first three-lens laminated lens is determined so as to satisfy the conditional expression (2), higher-order spherical aberration is generated, and the spherical aberration of the photographing lens for the three-plate camera is generated. Can be controlled and high image quality can be obtained.
- the second three-lens cemented lens may be configured to satisfy the following conditional expressions (3) and (4).
- n2G1 is the refractive index of the first lens from the subject side of the second three-piece lens
- n2G2 is the refractive index of the second lens from the subject side of the second three-piece lens
- n2G3 is the refractive index of the third lens from the subject side of the second three-lens cemented lens.
- the refractive index of each lens of the second three-lens bonded lens is determined so as to satisfy the conditional expressions (3) and (4), high-order spherical aberration is generated, and photographing for a three-plate camera is performed. It can control the spherical aberration of the lens and obtain high image quality.
- MTF ModulationModTransfer Function
- It is a spherical aberration diagram of a photographic lens for a three-plate camera that does not include a color separation prism. It is a figure which shows an astigmatism, a distortion aberration, and a magnification chromatic aberration in an order from the left of the photographic lens for 3 plate type cameras which does not include a color separation prism.
- the rear conversion lens according to the present technology (hereinafter referred to as the present optical system) is used after being placed on the photographing lens for a three-plate camera.
- the photographing lens for a three-plate camera is designed on the assumption that a color separation prism is used. Therefore, when combined with a single-plate color camera that does not use a color separation prism, spherical aberration that has fallen significantly toward the subject due to the absence of the color separation prism and longitudinal chromatic aberration due to the difference in refractive index due to the wavelength of the prism glass Will occur.
- a normal rear conversion lens simply converts the focal length of the photographic lens, and does not change the size of the image circle, but enlarges the image near the center of the photographic lens.
- this optical system expands the diameter of the image circle from the 2/3 inch format to the APS-C format by about 2.5 times. This is because the image pickup surface of the three-plate camera image pickup device has a small area, but the combined single-plate color camera image pickup device needs to have a large image pickup surface area.
- This optical system is premised on a photographing lens for a three-plate camera that is image-side telecentric to prevent color covering in the color separation prism.
- this optical system itself has telecentricity on the image side, and the light beam is vertically incident on the light receiving element on the imaging surface, the light receiving element on the periphery of the imaging surface also has a color filter in the light receiving element.
- the light beam enters perpendicularly. Therefore, the captured image can obtain a vivid color tone with no color turbidity up to the peripheral portion.
- the optical system according to the present technology is designed on the premise that the optical system is placed behind a photographic lens for a three-plate camera.
- the photographing lens for a three-plate camera is originally designed on the assumption that it is used in combination with a three-plate camera.
- a total of 40 mm such as a color separation prism and filters, for example, a quartz filter 3.15 mm, an N-BAF52 filter 33.02 mm, an S-BSL7 filter 10.05 mm, between the imaging lens for the three-plate camera and the image sensor. It is assumed that the above glass exists. Note that the flange back of the photographing lens is, for example, 48 mm (in Air).
- a typical design technique for a rear conversion lens is based on the premise that the principal ray is emitted from the position of the exit pupil minus in the front taking lens. That is, it is a premise that a light beam emitted from a photographic lens having a finite minus exit pupil distance enters the rear conversion lens. Furthermore, the light beam exiting the rear conversion lens is also designed to have a finite minus exit pupil distance.
- a convex lens group is arranged on the lens closest to the subject, the divergence of chief rays is stopped once, and a concave lens group is arranged on the image plane side of the lens group.
- the basic design is determined so that the focal length is increased by narrowing the luminous flux.
- This basic design is used to reduce the size of the rear conversion lens. Instead of realizing a reduction in size, the exit pupil distance on the image side of the rear conversion lens is generally shorter than the exit pupil distance of the original photographing lens.
- the angle of the light beam incident on the film surface was increased by the rear conversion lens that shortened the exit pupil distance.
- the exit pupil distance is shortened, the angle of the light beam incident on the light receiving element in the periphery of the image sensor deviates from the vertical, and there is insufficient light quantity or color turbidity in the image periphery. It becomes a cause.
- the present technology is also intended to enlarge the image circle. Therefore, when the basic design described above is adopted, the incident angle of the light beam in the light receiving element in the periphery of the image sensor is There was a problem that it was far from the vertical.
- the exit pupil position may be moved to infinity so that the light beam is vertically incident on the light receiving element in the periphery of the image sensor. It becomes a design constraint when designing a digital camera.
- FIG. 1 shows a sectional view along the optical axis of the present optical system.
- the flange surface FP of the photographic lens for a three-plate camera At the left end of the figure is the flange surface FP of the photographic lens for a three-plate camera, and at the right end of the figure is the imaging surface IMG of the image sensor.
- Sn represents the nth surface counted from the subject side
- Ln represents the nth lens counted from the subject side
- Fn represents the nth filter counted from the subject side
- Dn represents n counted from the subject side. Represents the distance between the faces.
- the filter FL1 is equivalent to a cover glass or ND (NeutralutDensity) glass, and the filters FL2 to FL4 are camera built-in glasses such as a crystal filter and other filters. Further, for example, as shown in FIG. 17, the present optical system is combined with a casing 10 that holds the present optical system.
- a casing 10 that holds the present optical system.
- first mount portion (first connection portion) 20 for connecting the housing 10 to a three-lens camera photographing lens
- second mount part (second connection part) 30 for connecting the housing 10 to a single-plate color camera.
- This optical system is an optical system consisting of 9 lenses in 3 groups, and is premised on the fact that the light beam incident from the photographic lens for a 3-plate camera is telecentric. This optical system is also telecentric on the image plane side. It has an optical design.
- the lens configuration of this optical system is in order from the subject side.
- Concave meniscus lens L1 with the concave surface facing the image side (2) Biconvex lens L2 (3) Biconcave lens L3 (4) Biconcave lens L4 (5) Biconvex lens L5 (6) Biconvex lens L6 (7) Biconcave lens L7 (8) Biconvex lens L8 (9) Biconvex lens L9 It becomes.
- a concave lens group (a first lens group, a first three-lens bonded lens) having a three-sheet bonding configuration is configured.
- an afocal lens group (second three-lens cemented lens) having a three-lens configuration is configured, and an aberration correction group (in combination with the single lenses L4 and L5) The second lens group).
- the lens L9 constitutes a convex lens group (third lens group) having an image forming function.
- the first condition is that the combined focal length of the first lens group, that is, the first three-lens bonded lens in which the lenses L1 to L3 are bonded is negative.
- This condition is an effective condition for reducing the size of this optical system, which is an enlargement optical system combined with a three-plate camera photographing lens whose image side is telecentric. This is also a condition for making the image side of the photographing lens for a three-plate camera telecentric and the image side of the present optical system telecentric. From the viewpoint of image enlargement, which is one of the purposes of the present optical system, the focal length of the first lens group must be negative.
- this optical system enlarges the image circle and uses a large area, so that the influence of the field curvature aberration becomes large. Therefore, this condition is important for improving the field curvature aberration.
- the second condition is that the combined focal length of the second three-lens bonded lens and the third lens group, that is, the combined focal length from the lenses L6 to L9 is positive.
- This condition is also an effective condition for reducing the size of the present optical system, which is an enlargement optical system combined with a three-plate camera photographing lens whose image side is telecentric, as in the above condition.
- An essential condition for downsizing the optical system is to make the focal length of the first lens group negative and make the focal length of the second lens group positive.
- the third condition is to satisfy the following conditional expression (1). ⁇ 3.0 ⁇ (f2G) / (f1G) ⁇ 1.2 (1)
- f1G is a composite focal length of the first three-sheet cemented lens
- f2G is a composite focal length of the second three-lens lens
- the fourth condition is to satisfy the following conditional expression (2). n1G1>n1G3> n1G2 (2)
- n1G1 is the refractive index of the first lens L1 from the subject side of the first three-piece lens
- n1G2 is the refractive index of the second lens L2 from the subject side of the first three-piece lens
- n1G3 is the refractive index of the third lens L3 from the subject side of the first three-lens cemented lens.
- this condition is a condition for generating high-order spherical aberration in the first lens group to control the spherical aberration of the photographic lens for the three-plate camera and obtaining high image quality.
- the absolute condition is that the refractive index (n1G2) of the central lens L2 is the lowest among the refractive indexes of the three lenses.
- the condition that the refractive index (n1G1) of the lens L1 closest to the subject among the three lenses is larger than the refractive index (n1G3) of the lens L3 closest to the image plane is the design condition of the photographic lens for the three-plate camera assumed this time. It is decided based on this.
- the fifth condition is to satisfy the following conditional expressions (3) and (4). n2G2> n2G1 (3) n2G2> n2G3 (4)
- n2G1 is the refractive index of the first lens L6 from the subject side of the second three-piece lens
- n2G2 is the refractive index of the second lens L7 from the subject side of the second three-piece lens
- n2G3 is the refractive index of the third lens L8 from the subject side of the second three-lens cemented lens.
- this condition is a condition for generating high-order spherical aberration in the second three-lens cemented lens to control the spherical aberration of the photographing lens for the three-plate camera and obtaining high image quality. is there. It is a typical condition for controlling the spherical aberration that the refractive index (n2G2) of the central lens L7 is the highest among the three lenses among the three lenses.
- R is the radius of curvature of each lens surface (optical surface)
- D is the distance on the optical axis of the lens surface
- Nd is the refractive index of each lens or filter (optical medium) with respect to the d-line (587.6 nm)
- Vd Represents the Abbe number of the d-line of each lens (optical medium).
- the units of the radius of curvature R, the surface interval D, and the effective radius are all in millimeters (mm).
- FIG. 2 is an optical path diagram of the present optical system.
- the aberration diagram of the present optical system is shown first, and then the aberration diagram including the color separation prism of the photographic lens for the three-plate type camera assumed by the present optical system is shown. Finally, aberration diagrams of the photographing lens for a three-plate camera with the color separation prism removed are shown.
- the difference in scale between the coma aberration diagram including the color separation prism and the coma aberration diagram not including the color separation prism of the photographing lens for a three-plate camera Since the former scale is ⁇ 0.01 mm, the latter scale is ⁇ 0.5 mm, and it can be seen that the order of coma aberration is 50 times different depending on the presence or absence of the color separation prism.
- FIG. 3 is a coma aberration diagram of the present optical system, and the drawing scale is ⁇ 0.02 mm.
- the left side of the figure is the meridional plane, and the right side is the sagittal plane.
- the aberrations are image heights of 14 mm, 11 mm, 7 mm, and 0 mm in order from the top of the figure.
- FIG. 4 is a spherical aberration diagram of this optical system, in which the vertical axis represents the height of the light beam and the horizontal axis represents the distance in the optical axis direction.
- the drawing scale is ⁇ 0.1 mm.
- FIG. 5 is a diagram showing astigmatism, distortion, and lateral chromatic aberration of this optical system in order from the left.
- the vertical axis represents the image height
- the horizontal axis represents the amount of defocus.
- the vertical axis represents the image height
- the horizontal axis represents the amount of image distortion.
- the drawing scales are ⁇ 0.1 mm, ⁇ 2%, and ⁇ 0.02 mm, respectively.
- the solid line in the astigmatism diagram represents the meridional direction, and the broken line represents the sagittal direction.
- FIG. 6 is a spot diagram of this optical system, and the drawing scale is 0.05 mm from the center to the end of the cross.
- the lower left figure shows an image height of 0 mm
- the upper left figure shows an image height of 7 mm
- the lower right figure shows an image height of 11 mm
- the upper right figure shows an image height of 14 mm.
- FIG. 7 is a white MTF (Modulation Transfer Function) characteristic diagram of this optical system, in which the vertical axis represents contrast (modulation) and the horizontal axis represents spatial frequency.
- the lower left figure shows an image height of 0 mm
- the upper left figure shows an image height of 7 mm
- the lower right figure shows an image height of 11 mm
- the upper right figure shows an image height of 14 mm.
- FIG. 8 is a defocus MTF characteristic diagram of this optical system, in which the vertical axis represents contrast (modulation) and the horizontal axis represents the focus shift position.
- the defocus width is ⁇ 0.1 mm.
- the lower left figure shows an image height of 0 mm
- the upper left figure shows an image height of 7 mm
- the lower right figure shows an image height of 11 mm
- the upper right figure shows an image height of 14 mm.
- FIG. 9 is a spherical aberration diagram of a photographic lens for a three-plate camera including a color separation prism.
- the vertical axis represents the ray height and the horizontal axis represents the distance in the optical axis direction.
- the drawing scale is ⁇ 0.01 mm.
- FIG. 10 is a coma aberration diagram of a photographing lens for a three-plate camera including a color separation prism, and a drawing scale is ⁇ 0.01 mm.
- the left side of the figure is the meridional plane, and the right side is the sagittal plane.
- the aberrations are image heights of 5.8 mm, 5 mm, 4 mm, and 0 mm in this order from the top.
- FIG. 11 is a diagram showing astigmatism, distortion aberration, and lateral chromatic aberration of a three-plate camera photographing lens including a color separation prism in order from the left.
- the vertical axis represents the image height
- the horizontal axis represents the amount of defocus.
- the vertical axis represents the image height
- the horizontal axis represents the amount of image distortion.
- the drawing scales are ⁇ 0.01 mm, ⁇ 0.3%, and ⁇ 0.002 mm, respectively.
- the solid line in the astigmatism diagram represents the meridional direction, and the broken line represents the sagittal direction.
- FIG. 12 is a white MTF characteristic diagram of a photographic lens for a three-plate camera including a color separation prism.
- the vertical axis represents contrast (modulation), and the horizontal axis represents spatial frequency.
- the lower left figure shows an image height of 0 mm
- the upper left figure shows an image height of 4 mm
- the lower right figure shows an image height of 5 mm
- the upper right figure shows an image height of 5.8 mm.
- FIG. 13 is a spherical aberration diagram of a photographic lens for a three-plate camera that does not include a color separation prism.
- the vertical axis represents the ray height, and the horizontal axis represents the distance in the optical axis direction.
- the drawing scale is ⁇ 0.5 mm.
- FIG. 14 is a diagram showing astigmatism, distortion aberration, and lateral chromatic aberration of a three-plate camera photographing lens that does not include a color separation prism in order from the left.
- the vertical axis represents the image height
- the horizontal axis represents the amount of defocus.
- the vertical axis represents the image height
- the horizontal axis represents the amount of image distortion.
- the drawing scales are ⁇ 0.01 mm, ⁇ 0.3%, and ⁇ 0.002 mm, respectively.
- the solid line in the astigmatism diagram represents the meridional direction, and the broken line represents the sagittal direction.
- FIG. 15 is a coma aberration diagram of a photographic lens for a three-plate camera that does not include a color separation prism, and a drawing scale is ⁇ 0.5 mm.
- the left side of the figure is the meridional plane, and the right side is the sagittal plane.
- the aberrations are image heights of 5.8 mm, 5 mm, 4 mm, and 0 mm in this order from the top.
- FIG. 16 is a white MTF characteristic diagram of a photographic lens for a three-plate camera that does not include a color separation prism.
- the vertical axis represents contrast (modulation), and the horizontal axis represents spatial frequency.
- the lower left figure shows an image height of 0 mm
- the upper left figure shows an image height of 4 mm
- the lower right figure shows an image height of 5 mm
- the upper right figure shows an image height of 5.8 mm.
- this technique can also take the following structures.
- a housing having two opposite ends and having a light transmission port at each of the ends; One end of the housing is attached to and detached from the image plane side of a photographic lens designed on the assumption that it is used in combination with a color separation prism of a three-plate camera having three first image sensors.
- Rear conversion lens provided.
- the third lens group is a rear conversion lens configured by a convex lens.
- (4) The rear conversion lens according to (2) or (3), The first three-sheet bonded lens and the second three-sheet bonded lens are: Rear conversion lens that satisfies the following conditional expression (1). ⁇ 3.0 ⁇ (f2G) / (f1G) ⁇ 1.2 (1) However, f1G is a composite focal length of the first three-lens laminated lens, f2G is the combined focal length of the second three-lens laminated lens.
- the first three laminated lenses are: Rear conversion lens that satisfies the following conditional expression (2).
- n1G1>n1G3> n1G2 (2)
- n1G1 is the refractive index of the first lens from the subject side of the first three-ply lens
- n1G2 is the refractive index of the second lens from the subject side of the first three-ply lens
- n1G3 is the refractive index of the third lens from the subject side of the first three-lens cemented lens.
- the second three-sheet bonded lens is A rear conversion lens that satisfies the following conditional expressions (3) and (4).
- n2G1 is the refractive index of the first lens from the subject side of the second three-ply lens
- n2G2 is the refractive index of the second lens from the subject side of the second three-ply lens
- n2G3 is the refractive index of the third lens from the subject side of the second three-ply lens.
- Dn n-th inter-surface distance from the subject side
- FLn n-th filter from the subject side
- FP flange surface with a three-lens camera lens
- IMG imaging surface of the image sensor
- Ln nth image from the subject side
- Lens SC Sensor cover Sn ... Surface of the nth lens or filter from the subject side 10 ... Housing 20 ... First mount portion 30 ... Second mount portion
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Abstract
Description
-3.0<(f2G)/(f1G)<-1.2 … (1)
但し、f1Gは前記第1の3枚貼り合わせレンズの合成焦点距離、f2Gは前記第2の3枚貼り合わせレンズの合成焦点距離である。
n1G1>n1G3>n1G2 … (2)
但し、n1G1は前記第1の3枚貼り合わせレンズの被写体側から1枚目のレンズの屈折率、n1G2は前記第1の3枚貼り合わせレンズの被写体側から2枚目のレンズの屈折率、n1G3は前記第1の3枚貼り合わせレンズの被写体側から3枚目のレンズの屈折率である。
n2G2>n2G1 … (3)
n2G2>n2G3 … (4)
但し、n2G1は前記第2の3枚貼り合わせレンズの被写体側から1枚目のレンズの屈折率、n2G2は前記第2の3枚貼り合わせレンズの被写体側から2枚目のレンズの屈折率、n2G3は前記第2の3枚貼り合わせレンズの被写体側から3枚目のレンズの屈折率である。
[本技術の特徴]
本技術にかかるリアコンバージョンレンズ(以下、本光学系という)は、上述のとおり、3板式カメラ用撮影レンズに後置して利用するものである。3板式カメラ用撮影レンズは、色分解プリズムの使用を前提に設計されている。そのため、色分解プリズムを用いない単板式カラーカメラと組み合わせる場合、色分解プリズムが無くなった事による、被写体側に極めて大きく倒れた球面収差と、プリズムガラスの波長による屈折率の差異に起因する縦色収差が発生する。本光学系では、これらの収差を補正することにより、3板式カメラ用撮影レンズを3板式カメラと共に用いた際の収差形状とほぼ同等の収差形状を、3板式カメラ用撮影レンズと単板式カラーカメラとの組み合わせでも実現している。
通常のリアコンバージョンレンズは、撮影レンズの焦点距離を変換するだけのものであり、イメージサークルの大きさは変えず、撮影レンズの中心付近の像を拡大する。これに対し、本光学系は、イメージサークルの直径を2/3インチフォーマットのものからAPS-Cフォーマットのものへ、約2.5倍に拡大するものである。これは、3板式カメラ用撮像素子の撮像面が小さな面積であるのに対し、組み合わせる単板式カラーカメラ用撮像素子には、撮像面の面積が大きいものを用いるニーズがある為である。
本光学系は、色分解プリズムにおける色被り対策のために像側テレセントリックとなっている3板式カメラ用撮影レンズを前提としている。また、本光学系自体も、像側にテレセントリック性を持たせ、撮像面の受光素子に対し光束を垂直に入射させているので、撮像面周辺部の受光素子においても受光素子内の色フィルターに対して光束が垂直に入射する。そのため、撮像された画像は周辺部まで色濁りが無い鮮やかな色調を得ることが出来る。
本技術にかかる光学系は、3板式カメラ用撮影レンズに後置されることを前提に設計されている。3板式カメラ用撮影レンズは、本来3板式カメラと組み合わせて使用されることを想定して設計されている。
リアコンバージョンレンズ(テレコンバージョンレンズ)の典型的な設計技法では、前置される撮影レンズにおいて主光線が射出瞳マイナスの位置から出ていることを前提としている。すなわち有限マイナスの射出瞳距離を持つ撮影レンズから射出される光束がリアコンバージョンレンズに入射する前提である。そしてさらに、リアコンバージョンレンズを出た光束も有限マイナスの射出瞳距離を持つように設計される。
図1に、本光学系の光軸に沿った断面図を示す。図の左端に、3板式カメラ用撮影レンズのフランジ面FPがあり、図の右端に、撮像素子の撮像面IMGがある。Snは被写体側から数えたn番目の面を表し、Lnは被写体側から数えたn番目のレンズを表し、Fnは被写体側から数えたn番目のフィルターを表し、Dnは被写体側から数えたn番目の面間距離を表す。
(1)像側に凹面を向けた凹メニスカスレンズL1
(2)両凸レンズL2
(3)両凹レンズL3
(4)両凹レンズL4
(5)両凸レンズL5
(6)両凸レンズL6
(7)両凹レンズL7
(8)両凸レンズL8
(9)両凸レンズL9
となる。
本光学系の成立条件は、以下のとおりである。
第1の条件は、第1のレンズ群、すなわちレンズL1からL3までを貼り合わせた第1の3枚貼り合わせレンズの合成焦点距離が負になることである。
第2の条件は、第2の3枚貼り合わせレンズおよび第3のレンズ群の合成焦点距離、すなわちレンズL6からL9までの合成焦点距離が正になることである。
第3の条件は、以下の条件式(1)を満たすことである。
-3.0<(f2G)/(f1G)<-1.2 … (1)
第4の条件は、以下の条件式(2)を満たすことである。
n1G1>n1G3>n1G2 … (2)
第5の条件は、以下の条件式(3)および(4)を満たすことである。
n2G2>n2G1 … (3)
n2G2>n2G3 … (4)
ここでは、レンズ面データの具体的な数値実施例を挙げる。なお、Rは各レンズ面(光学面)の曲率半径、Dはレンズ面の光軸上での間隔、Ndは各レンズやフィルター(光学媒質)のd線(587.6nm)に対する屈折率、Vdは各レンズ(光学媒質)のd線のアッベ数を表している。また、曲率半径R、面間隔D、有効半径の単位はいずれもミリメートル(mm)である。
面番号 R D Nd Vd 有効半径 備考
0 10.00 撮影レンズフランジ面FP
1 ∞ 3.00 1.517 64.20 17.9 フィルター類FL1
2 ∞ 10.60
3 156.00 1.70 1.883 40.80 13.6 レンズ1枚目L1
4 18.40 8.20 1.640 34.57 12.4 レンズ2枚目L2
5 -200.90 1.70 1.729 54.67 12.0 レンズ3枚目L3
6 35.85 11.17 11.5
7 -42.50 2.00 1.729 54.67 11.9 レンズ4枚目L4
8 100.30 1.00 12.5
9 64.40 4.50 1.620 36.30 13.1 レンズ5枚目L5
10 -125.00 0.71 13.4
11 52.20 11.00 1.593 35.45 13.9 レンズ6枚目L6
12 -22.35 6.30 1.834 37.34 13.9 レンズ7枚目L7
13 27.80 10.50 1.541 47.00 15.3 レンズ8枚目L8
14 -168.00 0.51 16.6
15 69.50 11.50 1.518 58.96 17.9 レンズ9枚目L9
16 -31.74 1.00 18.3
17 ∞ 0.25 1.523 59.44 17.7 フィルター類FL2
18 ∞ 2.50 1.549 69.92 17.7 フィルター類FL3
19 ∞ 0.30 1.517 64.20 17.7 フィルター類FL4
20 ∞ 11.56 16.5
21 ∞ 0.70 1.517 64.20 16.5 センサーカバーSC
22 ∞ 1.00 16.5
23 ∞ 0.00 28.0 像面IMG
ここでは、光路図や収差図等について説明する。図2は、本光学系の光路図である。収差図に関しては、最初に本光学系の収差図を示し、次に、本光学系が前提とする3板式カメラ用撮影レンズの、色分解プリズムを含めた収差図を示す。最後に、色分解プリズムを外した状態での3板式カメラ用撮影レンズの収差図を示す。
その他、本技術は、上述の実施形態にのみ限定されるものではなく、本技術の要旨を逸脱しない範囲内において種々変更を加え得ることは勿論である。
なお、本技術は以下のような構成も採ることができる。
(1)
対向する2つの端部を有し、前記各々の端部に光の透過口を有する筐体と、
3つの第1の撮像素子を有する3板式カメラの、色分解プリズムと組み合わされて使用されることを前提に設計された撮影レンズの像面側に、前記筐体の一方の前記端部を着脱自在に連結するための第1の連結部と、
前記3板式カメラの前記第1の撮像素子の撮像面より広い撮像面を有する第2の撮像素子を有する単板式カラーカメラに、前記筐体の他方の前記端部を着脱自在に連結するための第2の連結部と、
合成焦点距離が負である第1のレンズ群、球面収差を補正する第2のレンズ群、および結像作用を有する第3のレンズ群を前記筐体内に被写体側より順に配置した光学系と
を具備するリアコンバージョンレンズ。
(2)
前記(1)に記載のリアコンバージョンレンズであって、
前記第1のレンズ群は、第1の3枚貼り合わせレンズにより構成され、
前記第2のレンズ群は、被写体側より順に、凹レンズと、凸レンズと、第2の3枚貼り合わせレンズとにより構成され、
前記第3のレンズ群は、凸レンズにより構成される
リアコンバージョンレンズ。
(3)
前記(2)に記載のリアコンバージョンレンズであって、
前記第2の3枚貼り合わせレンズおよび前記第3のレンズ群の合成焦点距離は正である
リアコンバージョンレンズ。
(4)
前記(2)または(3)に記載のリアコンバージョンレンズであって、
前記第1の3枚貼り合わせレンズおよび前記第2の3枚貼り合わせレンズは、
以下の条件式(1)を満足する
リアコンバージョンレンズ。
-3.0<(f2G)/(f1G)<-1.2 … (1)
但し、
f1Gは前記第1の3枚貼り合わせレンズの合成焦点距離、
f2Gは前記第2の3枚貼り合わせレンズの合成焦点距離
である。
(5)
前記(2)から(4)のうちいずれか1つに記載のリアコンバージョンレンズであって、
前記第1の3枚貼り合わせレンズは、
以下の条件式(2)を満足する
リアコンバージョンレンズ。
n1G1>n1G3>n1G2 … (2)
但し、
n1G1は前記第1の3枚貼り合わせレンズの被写体側から1枚目のレンズの屈折率、
n1G2は前記第1の3枚貼り合わせレンズの被写体側から2枚目のレンズの屈折率、
n1G3は前記第1の3枚貼り合わせレンズの被写体側から3枚目のレンズの屈折率
である。
(6)
前記(2)から(5)のうちいずれか1つに記載のリアコンバージョンレンズであって、
前記第2の3枚貼り合わせレンズは、
以下の条件式(3)および(4)を満足する
リアコンバージョンレンズ。
n2G2>n2G1 … (3)
n2G2>n2G3 … (4)
但し、
n2G1は前記第2の3枚貼り合わせレンズの被写体側から1枚目のレンズの屈折率、
n2G2は前記第2の3枚貼り合わせレンズの被写体側から2枚目のレンズの屈折率、
n2G3は前記第2の3枚貼り合わせレンズの被写体側から3枚目のレンズの屈折率
である。
FLn… 被写体側からn枚目のフィルター類
FP … 3板式カメラ用撮影レンズとのフランジ面
IMG… 撮像素子の撮像面
Ln … 被写体側からn枚目のレンズ
SC … センサーカバー
Sn … 被写体側からn番目のレンズやフィルターの面
10 … 筐体
20 … 第1のマウント部
30 … 第2のマウント部
Claims (6)
- 対向する2つの端部を有し、前記各々の端部に光の透過口を有する筐体と、
3つの第1の撮像素子を有する3板式カメラの、色分解プリズムと組み合わされて使用されることを前提に設計された撮影レンズの像面側に、前記筐体の一方の前記端部を着脱自在に連結するための第1の連結部と、
前記3板式カメラの前記第1の撮像素子の撮像面より広い撮像面を有する第2の撮像素子を有する単板式カラーカメラに、前記筐体の他方の前記端部を着脱自在に連結するための第2の連結部と、
合成焦点距離が負である第1のレンズ群、球面収差を補正する第2のレンズ群、および結像作用を有する第3のレンズ群を前記筐体内に被写体側より順に配置した光学系と
を具備するリアコンバージョンレンズ。 - 請求項1に記載のリアコンバージョンレンズであって、
前記第1のレンズ群は、第1の3枚貼り合わせレンズにより構成され、
前記第2のレンズ群は、被写体側より順に、凹レンズと、凸レンズと、第2の3枚貼り合わせレンズとにより構成され、
前記第3のレンズ群は、凸レンズにより構成される
リアコンバージョンレンズ。 - 請求項2に記載のリアコンバージョンレンズであって、
前記第2の3枚貼り合わせレンズおよび前記第3のレンズ群の合成焦点距離は正である
リアコンバージョンレンズ。 - 請求項3に記載のリアコンバージョンレンズであって、
前記第1の3枚貼り合わせレンズおよび前記第2の3枚貼り合わせレンズは、
以下の条件式(1)を満足する
リアコンバージョンレンズ。
-3.0<(f2G)/(f1G)<-1.2 … (1)
但し、
f1Gは前記第1の3枚貼り合わせレンズの合成焦点距離、
f2Gは前記第2の3枚貼り合わせレンズの合成焦点距離
である。 - 請求項4に記載のリアコンバージョンレンズであって、
前記第1の3枚貼り合わせレンズは、
以下の条件式(2)を満足する
リアコンバージョンレンズ。
n1G1>n1G3>n1G2 … (2)
但し、
n1G1は前記第1の3枚貼り合わせレンズの被写体側から1枚目のレンズの屈折率、
n1G2は前記第1の3枚貼り合わせレンズの被写体側から2枚目のレンズの屈折率、
n1G3は前記第1の3枚貼り合わせレンズの被写体側から3枚目のレンズの屈折率
である。 - 請求項5に記載のリアコンバージョンレンズであって、
前記第2の3枚貼り合わせレンズは、
以下の条件式(3)および(4)を満足する
リアコンバージョンレンズ。
n2G2>n2G1 … (3)
n2G2>n2G3 … (4)
但し、
n2G1は前記第2の3枚貼り合わせレンズの被写体側から1枚目のレンズの屈折率、
n2G2は前記第2の3枚貼り合わせレンズの被写体側から2枚目のレンズの屈折率、
n2G3は前記第2の3枚貼り合わせレンズの被写体側から3枚目のレンズの屈折率
である。
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EP14756857.0A EP2940506A4 (en) | 2013-03-01 | 2014-02-14 | REVERSE CONVERSION LENS |
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US10012821B2 (en) | 2015-07-28 | 2018-07-03 | Canon Kabushiki Kaisha | Image pickup apparatus, rear attachment lens, and image pickup system including the same |
WO2017047229A1 (ja) | 2015-09-17 | 2017-03-23 | 富士フイルム株式会社 | レンズ装置、カメラシステム及び収差補正ユニット |
JP6797078B2 (ja) | 2017-05-31 | 2020-12-09 | 富士フイルム株式会社 | リアアタッチメントレンズ及び撮像装置 |
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- 2014-02-14 EP EP14756857.0A patent/EP2940506A4/en not_active Withdrawn
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EP2940506A1 (en) | 2015-11-04 |
EP2940506A4 (en) | 2016-08-24 |
JP2014170043A (ja) | 2014-09-18 |
JP5900379B2 (ja) | 2016-04-06 |
US20150355437A1 (en) | 2015-12-10 |
BR112015020507A2 (pt) | 2017-07-18 |
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