JP2018189860A - Photographic lens and photographing apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To solve the problem that ghost light as well as flare light lead to a cause of image quality degradation, the flare light spread over the whole screen can be easily corrected by image processing, but an amount of the flare light cannot be recognized and isolation between subject light and the flare light is impossible.SOLUTION: Sensors for measuring flare light are arranged in a lens. In this case, the sensors are arranged at a position which cannot be viewed from a lens aperture subject side and an image surface side. Further, the sensors are arranged closer to the image plane side than a diaphragm.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a photographic lens and a photographic device, and more particularly to a photographic lens flare removal process.

  When shooting with a digital camera or video camera, ghosts and flares may occur in a backlit scene, and these may be used as artistic expressions, but in most cases will degrade the image. It becomes. Here, the light rays incident on the photographing optical system are reflected by the photographing optical system and reach the image plane, and among the light rays, the condensed light beam is generally called a ghost and the diffused light ray is called a flare.

  Each optical surface is provided with an anti-reflection multilayer coating. However, when sunlight or the like directly enters the photographing optical system, ghost and flare cannot be prevented.

  As a technique for suppressing the occurrence of ghosts and flares, a method of reducing the variable aperture is known. Since ghost light and flare light are reflected by a plurality of surfaces of the lens and pass through an optical path different from that of photographing light, it is often possible to block the light by reducing the aperture.

  However, the ghost and flare suppression method by the aperture has a great influence on the photographic expression such as a reduction in exposure amount, an expanded depth of field, and a reduction in blur by the aperture.

  In order to solve these problems, Patent Document 1 discloses a photographing apparatus that photographs two images having different F values using a variable aperture and removes a ghost from the difference data of the two images by image processing. .

JP 2008-228181 A

  However, in the conventional technique disclosed in the above-mentioned Patent Document 1, it is necessary to perform photographing twice with an open aperture and a small aperture, and there is a possibility that a time difference between the two photographings may occur.

  In addition, since the ghost image is specified and removed using differential data in particular, it is difficult to specify and remove the flare over the entire screen. Further, it has been impossible to remove flare at the time of small aperture.

  An object of the present invention is to provide a photographing lens and a photographing device that can be obtained by information on a single photographing regarding flare removal and can also remove flare at a small aperture.

In order to achieve the above object, a photographic lens according to the present invention includes:
The flare light measurement sensor is arranged inside a lens barrel that is not directly visible from the subject side opening and the image side opening.

  According to the present invention, it is possible to provide a photographic lens and a photographing device that can perform flare removal with information from a single photographing and can also remove flare at a small aperture.

1 is a schematic diagram illustrating a photographing lens and a photographing device according to a first embodiment. Original image without flare Schematic diagram showing flare removal of a captured image of the first embodiment Schematic diagram showing a photographing lens and a photographing device of the second embodiment Schematic diagram showing flare removal of a captured image of the second embodiment The flowchart which shows a flare removal process of 1st Embodiment The schematic diagram which shows the sensor position of 2nd Embodiment

  Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings.

[First Embodiment]
FIG. 1 is a schematic diagram illustrating a schematic configuration of a photographing lens and a photographing device according to an embodiment of the present invention.

  The imaging device includes a lens system 2 and a camera body (imaging device body) 3. The lens system 2 includes a lens driving mechanism 5, a flare light measurement sensor 10, and a sensor control unit 11. The camera body 3 includes a camera control unit 6, an image engine 7, a recording unit 8, and an image sensor 9.

  The lens system 2 forms a subject image on the image sensor 9 through the lenses 12 and 14 and the variable diaphragm 13. The lens driving mechanism 5 is a mechanism that drives a focusing lens, an anti-vibration lens, and a diaphragm of a lens system. These are driven manually or electrically, and the driving state is grasped by an encoder or the like. In the lens system 2, a flare light measurement sensor 10 and a sensor control unit 11 are further arranged.

  The flare light measurement sensor is arranged on the image side of the stop in the lens barrel, at a position where it cannot be directly seen from the object side and the image side of the lens system 2. This is to prevent direct illumination when there is a high-luminance light source in the shooting screen. This is to eliminate the influence of regular reflection light not only from the object side but also from the sensor 9 surface. As a result, it is possible to detect only the reflected light inside the lens barrel.

  In response to an instruction from the camera control unit 6, the sensor control unit 11 converts the flare light amount detected by the flare light measurement sensor 10 into electronic information, accumulates it, and transmits it to the camera control unit.

  The camera body 3 is coupled to the lens system 2 by a mount 4. The camera control unit 6 in the camera body 3 controls the lens driving mechanism 5 through the electronic contacts of the mount 4 based on the release operation of the photographer. At that time, the lens driving state is grasped through the electronic contacts of the mount 4. At the same time as the release operation, the camera control unit 6 opens the shutter in the camera body 3 and exposes the captured image to the image sensor 9.

  The light beam imaged by the lens system 2 is converted into an electric signal by the image sensor 9. The electric signal is calculated as image information using the image engine 7 and is stored in the recording unit 8.

  A flare measurement amount in the flare light measurement sensor 10 is transmitted from the sensor control unit 11 to the camera control unit 6 through the mount 4. The camera control unit 6 calculates the flare amount on the image plane from the database based on the lens drive information from the lens drive mechanism 5 and the flare measurement amount. The calculated flare amount is subjected to flare removal by image processing from the captured image by the image engine 7.

  Hereinafter, processing in the camera control unit 6 will be described with reference to the flowchart of FIG. 6 and FIGS.

  FIG. 2 is an original image without flare.

  When photographing the subject of FIG. 2, the processing is started by the release operation of the photographer, and in step S01, the focusing drive of the lens system 2 and the narrowing operation of the variable diaphragm 13 are performed in preparation for photographing. Is called.

  In step S02, information on the lens state such as the lens driving state, zoom position, focus position, aperture value, and eccentric position during image stabilization is acquired, and the information is held in the camera control unit 6. In step S03, the flare measurement value of the flare light measurement sensor 10 is acquired through the sensor control unit 11 in the lens system 2.

  In step S04 by the photographing operation, the flared image of FIG. 3A imaged on the image sensor 9 is converted into an electrical signal and acquired as image information by the image engine 7. In step S05, the flare amount is calculated from the database based on the lens state information acquired in S02 and S03 and the flare measurement value.

  In step S06, the flare image is removed by the image engine 7 according to the flare calculation amount. FIG. 3B shows an image obtained by converting the calculated flare amount into an image. FIG. 3C obtained by subtracting FIG. 3B from FIG. 3A is an image after flare removal.

  In step S07, the image data after the image repair is stored in the recording unit 8.

  Hereinafter, the photographing lens and the photographing device according to the present embodiment will be further described.

  In the present embodiment, as shown in FIG. 1, only one flare light measurement sensor 10 is arranged. As shown in FIG. 3A, this is effective in the case where flare is uniformly applied to the entire screen. For example, a telephoto lens.

  In the telephoto lens, since the lens barrel is long, the light beam of the ghost light source 1 that reaches the lens system 14 on the image side from the stop is limited to an angle close to the optical axis. The light beam with a larger angle can be obtained with a hood attached to a lens barrel or lens. When the ghost light source 1 is in the screen or close to the screen, the flare is often uniform without being biased in the screen. In addition, since the angle of view is narrow, the fact that the range of the image plane is narrow with respect to the flare spread angle is also a cause of uniformity. In such a lens type, flare can be removed by performing flare measurement with only one sensor.

  As the arrangement location of the flare sensor 10, the image side is more preferable than the variable stop 13 as shown in FIG. On the object side of the variable aperture, the angle of the light beam reaching from the ghost light source 1 is wider than the angle of the light beam reaching the image side lens system 14. When shooting with a variable aperture, light that does not reach is also measured.

  Further, when the image sensor is arranged on the image side of the variable stop, it is necessary to arrange the flare light measurement sensor 10 at a place where it cannot be directly seen from the object side. This is because when the flare light measurement sensor 10 is directly visible from the object side, the ghost light source 1 may directly irradiate the sensor. Similarly, in order to eliminate the influence of specular reflection light from the sensor, it is arranged at a position where it cannot be directly seen from the image side.

  In order to measure flare light while eliminating the influence of direct light under the above conditions, an arrangement in which at least one optical surface with a convex surface facing the object side from the flare light measurement sensor 10 exists on the image side is preferable. This is because the reflection on the convex surface has the effect of diverging light rays.

  By arranging the flare sensor on the object side rather than the convex surface facing the object side, it becomes possible to stably measure the flare light amount regardless of the angle of the ghost light source 1.

  According to the present embodiment, in an imaging optical system such as a camera, it is possible to remove flare on an image, particularly regarding an optical system such as an interchangeable lens of a single-lens reflex camera.

[Second Embodiment]
Hereinafter, a photographing lens and a photographing device according to a second embodiment of the present invention will be described. In the present embodiment, as shown in FIG. 4, a plurality of flare light measurement sensors 10 are arranged.

  As shown in FIG. 5A, it is effective when the flare intensity is inclined with respect to the screen. For example, a wide angle lens. With a wide-angle lens, even if a hood is attached to the lens, the imaging angle of view is wide, so there is a high probability that the light from the ghost light source 1 will enter the lens system 2. A light beam having an angle with respect to the optical axis is also applied to the lens system 14 on the image side from the stop. Further, since the shooting angle of view is wide, it cannot be said that the screen size is sufficiently small with respect to the spread angle of the flare. Therefore, unlike the first embodiment, the flare is rarely uniform in the screen and often has an uneven strength.

  When the lens system 2 is a coaxial system, the flare is symmetric with respect to a certain straight line passing through the optical axis. Therefore, it is sufficient for the flare distribution to know the direction of inclination and the change in intensity (gradient).

  In the present embodiment, as shown in FIG. 7, four flare sensors 10 are arranged in the lens system 2 symmetrically with the optical axis. Each flare sensor is disposed in the vicinity of the image side of the variable diaphragm 13 and is disposed toward the variable diaphragm 13. Thereby, it is possible to measure not only the reflection on a specific lens surface but also the total of the reflected light of a plurality of lens surfaces.

  Based on the flare measurement value from the flare light measurement sensor 10 and the information on the state of the lens, the flare amount having an inclination is calculated from the database. FIG. 5B shows an image obtained by converting the calculated flare amount into an image. FIG. 5C, which is obtained by subtracting the flare from the original image FIG. 5A, shows the image after the flare removal.

  Regarding the flare light measurement sensor 10, the flare image can be calculated in more detail by further increasing the number of arrangements.

  The flare removal processing is not limited to the method of subtracting the calculated flare images of FIGS. 3B and 5B from the original images of FIGS. 3A and 5A. 3 (a) and 5 (a), which are original images, may be an image processing method based on a direct calculation for converting a tone curve or contrast. The numerical parameters at the time of image processing are calculated from the database based on the flare measurement value from the flare light measurement sensor 10 and the lens state information. 3C and 5C, which are images obtained as a result, are equivalent to the above.

Further, the image processing is not limited to the processing in the camera body 3. When the flare measurement value of the flare light measurement sensor 10 and the information on the lens state are recorded in the files shown in FIGS. 3A and 5A, which are the original images, and developed with a personal computer or the like. Alternatively, a method using the recording information may be used for determining the development parameters.
Alternatively, the flare amount is calculated from the database based on the flare measurement value of the flare light measurement sensor 10 and the lens state information, and the calculated flare amount is the original image shown in FIGS. 3A and 5A. ) May be recorded in the file.

  According to these methods, not only can the flare removal process be performed or not can be selected later, but also there is an advantage that the calculated parameters can be corrected according to the drawing intention.

  As mentioned above, although preferable embodiment of this invention was described, this invention is not limited to these embodiment, A various deformation | transformation and change are possible within the range of the summary.

1 ghost light source, 2 lens system, 3 camera body, 4 mount,
5 lens drive mechanism, 6 camera control unit, 7 image engine, 8 recording unit,
9 Image sensor, 10 Flare light measurement sensor, 11 Sensor control unit,
12 Lens system on the object side of the aperture, 13 Variable aperture,
14 Lens system on the image side from the stop

Claims (7)

An interchangeable photographic lens,
A photographic lens characterized in that the flare light measurement sensor is disposed inside a lens barrel that is not directly visible from the subject side opening or the image side opening.   The photographing lens according to claim 1, wherein the flare light measurement sensor is disposed on the image side from the diaphragm surface.   The photographing lens according to claim 2, wherein a lens having a convex surface directed toward at least one subject side is located closer to the image plane than the flare light measurement sensor.   The photographing lens according to claim 3, wherein at least two flare light measuring sensors are arranged. A photographing lens according to any one of claims 1 to 4, comprising:
A photographing apparatus, wherein measurement information of the flare light measurement sensor at the time of photographing is stored in the same file as image data. A photographing lens according to any one of claims 1 to 4, comprising:
An imaging apparatus, wherein parameters for flare-removed image processing are changed based on measurement information of the flare light measurement sensor at the time of imaging and camera setting information.   6. The photographing apparatus according to claim 5, wherein parameters in the flare removal image processing are changed based on measurement information of the flare light measurement sensor at the time of photographing and camera setting information.