JP2011114794A - Photographic apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a photographic apparatus that obtains satisfactory images when an attachment optical system is mounted on the apparatus. <P>SOLUTION: The photographic apparatus includes: an imaging element; a photographing optical system that zooms subject images that are formed on the photographing optical system; the attachment optical system that is attachable to the photographing optical system; and an image trimming module that electrically trims parts of available picture areas so that a center position of the available picture area of the imaging element and a center position of a circular image of the photographic optical system coincide in a predetermined zooming range that is determined while the photographing optical system is mounted on the attachment optical system. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a photographing apparatus including an attachment optical system that can be attached to and detached from a photographing optical system.

  In recent years, compact digital cameras and video cameras equipped with a photographing optical system have become widespread. In addition, in order to expand the photographing area, an attachment optical system that is attached to the photographing optical system and changes the angle of view is also widespread. When the attachment optical system is attached to the photographing optical system, an optical axis shift between the photographing optical system and the attachment optical system is likely to occur, and there is a risk of image position shift.

  By the way, Patent Document 1 discloses that when a converter and a photographing lens are mounted on a camera body capable of electronic zooming, the magnification range for trimming photographing is limited based on information calculated by the converter. With such a configuration, it is possible to always obtain a good image when using the electronic zoom.

JP-A-5-150292

  Currently, in order to obtain a wide-angle image, there is an attachment optical system configured to be mounted on the object side of the photographing optical system. However, when the optical axis of the attachment optical system is deviated from the optical axis of the photographing optical system, the image circle image formed on the image sensor is shifted. That is, the center position of the image circle image is shifted from the center position of the effective screen of the image sensor. This phenomenon becomes remarkable when the optical axes of each other are relatively inclined. Further, in the circumferential image shooting, the unbalance at the four corners of the screen is conspicuous, and thus the above-described shift is particularly emphasized, and the live view image or the recorded image of the subject becomes a low-quality image.

  The present invention provides a photographing apparatus capable of obtaining a good image when an attachment optical system is attached.

  An imaging apparatus according to one aspect of the present invention includes an imaging device, a shooting optical system that changes a subject image formed on the imaging device, an attachment optical system that is detachable from the shooting optical system, and the shooting The center position of the effective screen of the image sensor and the center position of the image circle image of the photographing optical system coincide with each other in a predetermined zooming area determined with the attachment optical system attached to the optical system. Image trimming means for electrically cutting out a part of the effective screen.

  Other objects and features of the present invention are illustrated in the following examples.

  ADVANTAGE OF THE INVENTION According to this invention, the imaging device which can obtain a favorable image when mounting | wearing with an attachment optical system can be provided.

It is an example of the change of the picked-up image when the attachment optical system is mounted on the photographing apparatus of the present embodiment and the signal change in the photographing apparatus. It is a figure which shows the positional relationship of the effective screen and image circle image in the imaging device of a present Example. It is a flow of an image trimming process when an attachment optical system is connected to the photographing apparatus of the present embodiment. It is a block diagram of the signal transmission path | route at the time of connecting an attachment optical system to the imaging device of a present Example. It is a flow of an image trimming process when an attachment optical system is connected to the photographing apparatus of the present embodiment. It is an optical path figure at the time of combining the imaging optical system and attachment optical system of a present Example.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. In each figure, the same members are denoted by the same reference numerals, and redundant description is omitted.

  FIG. 1 shows a change in a photographic image of a photographing apparatus and a state of a signal change in the photographing apparatus in a state where an attachment optical system having an ultra-wide angle angle of view is attached to a photographing apparatus capable of image scaling. . FIG. 1 shows a case where the optical axis of the attachment optical system and the optical axis of the photographing optical system are shifted from each other.

  P1 to P5 in FIG. 1 are examples of changes in the captured image when the wide-angle end state is changed to the telephoto end state by the image scaling operation of the imaging apparatus. Here, the range of P1 to P2 is a state where the entire image circle image of the photographing optical system is photographed (hereinafter referred to as “circumferential image”). P3 (range of P2 to P4) is a state where the image is captured in a partially vignetting image state (a state in which a part of the circumferential image remains, hereinafter referred to as an “intermediate image”). Further, the range of P4 to P5 is a state in which the effective image area portion in the circumferential image is cut out (hereinafter referred to as “diagonal image”).

  In the position A in FIG. 1, when zooming is performed from the wide-angle end, the zooming is performed so that the circumferential image comes first in contact with either the upper or lower long side of the image size in the state where the photographed image is P2. Position. Further, the B position is an image magnification position where all vignetting in the four corner directions of the circumferential image disappears from the effective shooting area where the shot image is P4. Here, in the case of an ultra-wide-angle optical system or a fish-eye optical system, a part of the four corners of the circumferential image is asymmetrically vignetted to form a low-quality image, which is not preferable. For this reason, in the present embodiment, an electric image cutout means (hereinafter referred to as “image trimming means”) is used in a predetermined zoom area where vignetting asymmetry is conspicuous. Output as an image with vignetting symmetry. That is, an image in an appropriate range is electrically cut out from the effective screen of the image sensor, and the cut out image is output. The predetermined variable magnification region is, for example, a region (range P1 to P3) in which the diameter of the image circle image is shorter than the diagonal length of the effective screen of the image sensor.

  As one of the detection methods for vignetting, the center of the circle forming the image circle image is detected by extracting the contour of the image circle image, and the center point of the output screen and the detected image circle image are detected. There is a method of judging from the shift amount of the center point. In this case, the contour of the image circle image can be extracted in the state of P1 to P3 in FIG. On the other hand, in the state of P4 to P5, since the image in the image circle image is an output image, it is determined that image trimming is not necessary. At the same time, when the vignetting asymmetry needs to be removed, the relative positional relationship between the output screen and the image circle image can be grasped. Therefore, it is possible to obtain the necessary image trimming amount and image trimming position information.

  FIG. 2 shows the positional relationship between the effective screen electrically output by the image sensor and the image circle image formed on the image sensor by the photographing optical system. 2A shows a state in which the center position α of the image circle image 200 in the zoomed state of P1 to P2 in FIG. 1 is shifted to the lower right with respect to the center position β of the effective screen 100 of the image sensor. Indicates. FIG. 2B shows a state in which the center position α of the image circle image 200 in the zoomed state of P3 in FIG. 1 is shifted in the upper right direction with respect to the center position β of the effective screen 100.

  Here, the shift amount A in the long side direction and the shift amount B in the short side direction between the center position β of the effective screen 100 (shooting screen) of the image sensor and the center position α of the image circle image 200 of the shooting optical system are calculated. By comparison, the image trimming amount and the image trimming position are determined. The center position β of the effective screen 100 of the image sensor is known, and the center position α of the image circle image 200 of the photographing optical system can be calculated from the contour of the image circle image 200 detected. By calculating the difference between the center position β of the effective screen 100 and the center position α of the image circle image 200, a difference in the long side direction (deviation amount A) and a difference in the short side direction (deviation amount B). ).

  First, the image trimming direction reference is determined from the aspect ratio of the screen. Consider a case where A ′ = A · (H / G), where G is the short side of the effective screen 100 and H is the long side. Here, when A ′ <B, the image circle image 200 is displayed based on the difference (shift amount B) in the short side direction of the effective screen 100 so that the screen aspect ratio is maintained even after image trimming. The center position of the screen 300 after trimming is determined. On the other hand, when A ′ ≧ B, the difference in the long side direction (deviation amount A) becomes the reference.

  FIG. 2A shows an example in which the difference in the short side direction is used as a reference. Here, the distance between the upper long side of the effective screen 100 and the uppermost part of the contour of the image circle image 200 is C, and the distance between the lower long side 2 of the effective screen 100 and the lowermost part of the contour of the image circle image 200. Is a distance D. These distances C and D can be calculated from the position of the effective screen 100 and the contour of the image circle image 200. At this time, the image trimming amounts in the long side direction and the short side direction are H ′ = H · ((G− | CD −) / G) and G ′ = G · (H ′ / H), respectively. . The amount of movement of the image trimming center position moved from the image center before image trimming is + A in the long side direction of the effective screen (the right direction in the figure is a positive value), and − in the short side direction. B (the upward direction in the figure is a positive value).

  On the other hand, FIG. 2B is an example when the difference in the long side direction is used as a reference. Here, the distance between the rightmost part of the contour of the image circle image 200 and the right short side of the effective screen 100 is E, and the distance between the leftmost part of the contour of the image circle image 200 and the left short side of the effective screen 100 is Let F be the distance. These distances E and F can be calculated from the position of the effective screen 100 and the contour of the image circle image 200.

  At this time, the image trimming amounts in the long side direction and the short side direction are H ′ = H · ((H− | E−F |) / H) and G ′ = G · (H ′ / H), respectively. . The moving amount of the image trimming center position moved from the image center before image trimming is + A in the long side direction of the effective screen (the right direction in the figure is a positive value), and + B in the short side direction. (The upward direction in the figure is a positive value).

  As described above, by extracting the contour of the image circle image 200 and determining the positional relationship with the effective screen 100 of the image sensor, the image trimming method of the effective screen 100 of the image sensor is determined, and asymmetric vignetting at the four corners of the screen is determined. The removed output image can be obtained. The contour of the image circle image 200 does not need to be detected for the entire range imaged on the image sensor, and the contour positions of at least three points are detected as known by a circle interpolation method passing through three points. do it.

  Next, FIG. 3 shows a flow as an example of the above-described image trimming method. This flow is started when the attachment optical system is attached to the photographing apparatus (START). At this time, the image trimming process state is reset, and the image trimming process is not performed. Note that the flow in FIG. 3 is executed based on an instruction from the control unit in the photographing apparatus.

  First, in step # 401, the contour of the image circle image is extracted using the contour extracting means. Next, in step # 402, it is determined whether or not the contour extracting means has extracted the contour of the image circle image. If the contour cannot be extracted, the image is formed in a diagonal image state, or the subject image has many dark parts and does not give an unnatural impression to the photographer without performing image trimming. It is judged that there is. For this reason, it progresses to step # 410, without performing an image trimming process.

  On the other hand, if the contour is extracted, the process proceeds to step # 403, and the center position α of the image circle image 200 is calculated from the detected contour. In step # 404, the center position β of the effective screen 100 of the image sensor is calculated. Note that the center position β of the effective screen 100 of the image sensor need not be calculated each time, and the position information of the center position β may be stored in the storage unit in advance.

  Next, in step # 405, the shift amounts of the center positions α and β in the X direction and the Y direction on the screen plane are calculated. After calculating the shift amount, as described with reference to FIG. 2, the image trimming reference direction is determined in step # 406, and the image trimming amounts in the long side direction and the short side direction are respectively determined in steps # 407 and # 408. Calculated. In step # 409, image trimming processing is performed based on such information.

  In step # 410, the display image of the subject image (live view display image) is output to the display unit. At this time, when the image trimming process is performed, the image trimming process is effectively maintained for the output image unless the zooming operation, the power of the photographing apparatus is turned off, or the attachment optical system is removed. The Next, when a scaling operation is performed in step # 411, the image trimming process is reset in step # 412 (after the image trimming process is interrupted), and then a scaling drive operation is performed in step # 413. . Then, returning to step # 401, the contour extraction process of the image circle image 200 is performed again. In this embodiment, the contour of the image circle image is extracted using the contour extracting means, but the present invention is not limited to this, and the attachment optical system mounted on the photographing apparatus is identified and used in the variable magnification range. On the other hand, the image trimming area range may be stored in the storage unit.

  FIG. 4 is a block diagram of the photographing apparatus of the present embodiment, and is a schematic diagram of a signal transmission path when the attachment optical system barrel 1 (attachment optical system) is connected to the photographing apparatus 2 including the photographing optical system. . The photographing optical system has a function of changing the magnification of a subject image formed on the image sensor 19. Further, the attachment optical system lens barrel 1 is configured to be detachable from the photographing optical system.

  First, when the operator operates the magnification operation member 18, a magnification request signal is transmitted from the magnification operation signal generator 17 to the control unit 5, and optical magnification driving is performed by the imaging device 2. Next, when drive request information is transmitted from the control unit 5 to the first actuator drive circuit 11, a variable power lens is driven by a variable power lens group drive actuator 12 that drives the variable power lens group 7 constituting the photographing optical system. The group 7 is driven in the optical axis direction. At the same time, the position of the optical axis of the zoom lens group 7 is detected by the position detector 8 and the control unit 5 receives the position information signal. Further, in order to perform image plane position correction accompanying the above-described magnification operation and subject distance change, when the image magnification changes due to movement of the correction lens group 9 on the optical axis, the current subject distance information and the magnification lens are further changed. Position information on the optical axis of group 7 is referred to. Then, in order to determine the moving direction and moving amount of the correction lens group 9, drive request information is transmitted from the control unit 5 to the second actuator drive circuit 13. As a result, the zoom lens group 7 is moved on the optical axis by the drive actuator 14, the position of the zoom lens group 7 is detected by the position detection means 10, and the position information is received by the control unit 5.

  Next, for example, in the case of an autofocus method in which the focus determination is performed by evaluating the contrast value of the captured image from the image signal of the image sensor, when the subject distance changes, the electrical from the image sensor 19 in FIG. The focus evaluation device 20 performs focus evaluation on the image signal. Then, the correction lens group 9 is moved by a predetermined amount via the control unit 5.

  When the attachment optical system barrel 1 is connected to the imaging device 2, the connection transmission means 3 provided in the attachment optical system barrel 1 sends a predetermined signal to the connection detection means 4 provided in the imaging device 2. introduce. Next, the control unit 5 transmits from the connection detection means 4 that the attachment optical system barrel 1 has been connected. Further, based on information from the storage means 6 for storing the image trimming range, the position detection means 8 for the variable magnification lens group, and if necessary, the position detection means 10 for the image plane correction lens group, an image of the photographing optical system is obtained. Image trimming range information in accordance with the scaling value information is extracted. The control unit 5 includes image trimming means. The image trimming means electrically applies a part (screen 300) of the effective screen 100 such that the center position β of the effective screen 100 of the image sensor 19 and the center position α of the image circle image 200 of the photographing optical system coincide with each other. cut. As described above, the image trimming process by the image trimming means is performed in a predetermined zooming area determined in a state where the attachment optical system lens barrel 1 is attached to the photographing optical system. In the present embodiment, the storage means 6 is provided in the photographing apparatus 2, but the storage means 6 may be provided in the attachment optical system barrel 1 as long as electrical communication with the photographing apparatus 2 is possible at the time of wearing. Good.

  In this embodiment, the image magnification change value information is represented, for example, by the ratio of the focal length at the wide angle end to the focal length of the photographing optical system at the current position of the variable magnification lens group 7. However, when the magnification change state (focal length change) changes greatly due to the movement of the correction lens group 9, the focal length change ratio with respect to the focal length at the wide angle end is calculated from the information of both the position detection means 8 and 10. The method can be used. Further, the current magnification information may be extracted from corresponding positions stored in the photographing apparatus 2 from both the magnification lens group position and the image plane correction lens group position.

  Further, when the zooming state does not change due to the movement of the correction lens group 9, the current zooming information may be acquired only from the position information of the zooming lens group 7. As the position detection means of the present embodiment, a device that determines the resistance value by linking the lens group drive and the resistance value changing member of the variable resistor, a device that accumulates the number of drive pulses from the reference position of the stepping motor, and the like are used. It is done. The amount of image trimming range stored in the storage unit 6 is, for example, each of the imaging optical systems provided in the imaging apparatus 2 using a tool for determining the image trimming range by extracting the contour of the image circle image 200. A value corresponding to the zoom range may be stored. The control unit 5 also controls the external display device driving circuit 15 so as to output an image to the external display device 16 such as a liquid crystal.

  Next, FIG. 5 shows a flow of the above-described image trimming process. Similar to the description of FIG. 3, the flow of FIG. 5 is started when the attachment optical system is attached to the photographing apparatus (START). At this time, the image trimming processing state is reset, and the image trimming is not performed. Further, steps # 409 to # 413 in FIG. 5 are the same as the step numbers in the description of FIG. 3, and a specific description thereof is omitted here. Note that the flow in FIG. 5 is executed based on an instruction from a control unit in the photographing apparatus.

  First, when the attachment optical system is attached to the photographing apparatus, in step # 601, as described with reference to FIG. 1, the magnification position B at which the imaging state on the image sensor becomes a diagonal image in the magnification range of the photographing optical system is obtained. Set. Note that the zoom position B is preferably stored in advance in the storage unit in consideration of the shift amount of the image circle image generated by the combination of the attachment optical system and the photographing optical system.

  Next, in step # 602, the current zoom position information of the photographing optical system is acquired. The zoom position information is stored in the storage means. In step # 603, it is determined whether or not the current zoom position is located on the wide angle side with respect to the zoom position B. At this time, when it is on the telephoto side from the zoom position B, it is determined that the image formed on the image sensor is a diagonal image. For this reason, it progresses to step # 410, without performing an image trimming process. On the other hand, if it is determined in step # 603 that the current zoom position is on the wide angle side from the zoom position B, in step # 604, image trimming information corresponding to the zoom position stored in advance is acquired. In the next step # 409, image trimming processing is performed. Hereinafter, steps # 410 to # 413 are the same as those described in the flow of FIG.

  Even when a method of storing image trimming information in advance is used, the above-described image circle image contour extracting means may be used in combination. Step # 410 shown in the flow of FIGS. 3 and 5 is an example of outputting an image to an external display device such as a liquid crystal, but is output to the storage device in accordance with the photographing start operation of the photographing device. Similar processing may be performed on the image information.

  FIG. 6 is an example of a schematic configuration when an attachment optical system having a wide angle of view is attached to a photographing optical system. In FIG. 6, the photographing optical system M is a zoom optical system having a two-group configuration including a negative lens group MB1 and a positive lens group MB2 from the object side. The photographing optical system M has a variable magnification structure that does not cause focal point movement even during variable magnification because the position from the imaging plane IP is changed along with the relative distance change between the negative lens group MB1 and the positive lens group MB2. The focus control is performed by moving the negative lens group MB1 in FIG. 6 in the optical axis direction. In FIG. 6, SP is an iris diaphragm, and FIL is a filter such as an infrared cut filter or a low-pass filter.

  AT is an attachment optical system, and L is an objective optical system having a positive refractive power composed of a front group B1 having a negative refractive power and a rear group B2 having a positive refractive power from the object side. F is a field lens group having a positive refractive power disposed in the vicinity of the imaging position of the objective optical system L. H is a positive lens group that has a positive refractive power and assists the aerial image formed by the objective optical system L to focus on the position of the imaging plane IP of the photographing optical system M.

  In FIG. 6, the optical system of the photographing apparatus is in the telephoto end state and obtains a diagonal image. In order to obtain a circumferential image, the attachment optical system is fixed, and the optical lens distances of the negative lens group MB1 and the positive lens group MB2 are separated from each other as indicated by arrows in FIG. And the zooming area may be changed to the wide angle side. By providing the attachment optical system with identification information generating means characterized by electrical characteristics such as resistance and energization pattern, the attachment state of the attachment optical system and the identification information can be transmitted to the imaging apparatus.

  According to the present embodiment, it is possible to provide a photographing apparatus (digital camera, video camera, etc.) capable of obtaining a good image when the attachment optical system is attached.

   The embodiment of the present invention has been specifically described above. However, the present invention is not limited to the matters described as the above-described embodiments, and can be appropriately changed without departing from the technical idea of the present invention.

DESCRIPTION OF SYMBOLS 1 Attachment optical system lens barrel 2 Imaging device 5 Control part 19 Image sensor

Claims (4)

An image sensor;
A photographic optical system for scaling a subject image to be imaged on the image sensor;
An attachment optical system detachable from the photographing optical system;
The center position of the effective screen of the image sensor and the center position of the image circle image of the photographing optical system coincide with each other in a predetermined zooming area determined with the attachment optical system attached to the photographing optical system. And an image trimming means for electrically cutting out a part of the effective screen.   The imaging apparatus according to claim 1, wherein the predetermined magnification region is a region in which a diameter of the image circle image is shorter than a diagonal length of the effective screen of the imaging element.   The image trimming unit includes a contour extracting unit that extracts a contour of the image circle image, and calculates the center position of the image circle image from the contour of the image circle image extracted by the contour extracting unit. The photographing apparatus according to claim 1 or 2, characterized in that Further comprising storage means for storing zoom position information of the photographing optical system;
4. The photographing apparatus according to claim 1, wherein the image trimming unit performs an image trimming process based on the scaling position information stored in the storage unit. 5.