JP2005274799A - Focus correcting device for af system interchangeable lens - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a focus correcting device capable of correcting the position of a standard focusing point being the reference of AF operation of a product by user's operation in a lens to be mounted. <P>SOLUTION: Focusing decision calculated by a range-finding calculation CPU 18 according to a range-finding signal obtained by a range-finding element 17 in ordinary AF operation is standardized from data in a ROM 27 being the reference of a storage part 26, and focusing is controlled according to the conventional AF operation. However, if a user is dissatisfied with the standard focusing operation of a taking lens 2 to be mounted and he (she) can obtain more accurate focusing operation in performing correction, he (she) can rewrite the data in the RAM 29 of a storage part 28 in the CPU 18 by operating a positive correction SW 24 and a negative correction SW 25. The focus correction performed after the lens 2 is mounted is continued while the lens 2 is mounted, and when the lens 2 is separated from a mount 4, the focus correction is released, and the lens is reset to the standard focusing operation. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to an AF operation of an interchangeable lens single-lens reflex camera, and more particularly to a focus correction apparatus for a system interchangeable lens provided with means capable of correcting the best focal position of a digital AF single-lens reflex camera.

  Recent digital cameras are becoming more sophisticated in photography, like conventional silver halide cameras. Along with this, there is a strong demand for system cameras, and in particular, the demand for AF single-lens reflex cameras with interchangeable lenses is growing, and each company is rushing to commercialize it.

  It can be said that it is a digital camera. Basically, it has many common features with conventional cameras. For AF single-lens reflex cameras, the lens mount is used instead of the conventional photosensitive film. In many cases, the arrangement of the mechanism such as the pentaprism and the focal plane shutter is followed as in the past. In particular, with respect to AF control, there are many models of the conventional system in which the light beam of the subject that has passed through a part of the main mirror is reflected by the sub-mirror and guided to the distance measuring element of the AF module installed outside the center subject optical path.

  For this reason, even if a lens system is newly developed for digital AF single-lens reflex cameras, the AF system is often changed to a lens system that can be shared with conventional silver halide cameras without changing the AF system. .

  In general, an image sensor installed on the focal plane of a digital camera has a shallow focal depth compared to a film, and requires strict positional accuracy of the focal plane. In particular, as the number of pixels of the image sensor has increased and the resolution has increased, there is an even greater need for focusing accuracy in AF operation, and the relative position accuracy of the AF module that is in optical co-relationship with the image sensor in the focal plane is high. Strictly required.

  However, in actual production sites, the position accuracy at the time of mounting the image sensor and the AF module and the focusing accuracy in the AF operation are generally advanced within the range of a standard that specifies an allowable error. In the interchangeable lens group shared with the salt camera, the error between the focus detection position of the AF sensor and the actual focal point of the focal plane caused by differences in focal length accuracy, lens brightness, and lens aberration is sufficient in the conventional silver salt camera Even if it is acceptable, it may not be acceptable for a digital camera, or depending on the lens to be mounted, moving the AF focus position slightly back and forth and correcting the focal position may improve image quality. This response is required.

  However, in actual camera manufacturing sites, it is controlled by strict standards that raise the accuracy of AF sensor and image sensor related components and combination, increase the focus accuracy in AF operation, and narrow the focus determination range. However, there is a limit to this, and adding correction data one by one for a camera / lens combination will require a huge amount of work, resulting in high costs and the introduction of a new system lens. It is impossible to deduce what combinations are used by market users.

  In view of this problem, even with a newly developed system lens, even if it is a lens that is not a problem for a sharable silver salt camera, when it is attached to a digital AF single-lens reflex camera, the compatibility between the camera and the lens Unfortunately, it is undeniable that there is a slight focus shift, so we can provide a solution to fix the focus position of the AF on the lens side so that the photographer can manually obtain the best focus. To do.

A focus correction apparatus during AF operation has already been proposed in Japanese Patent No. 2904595. This is because, during continuous shooting of the camera, a plurality of frames are shot while the focus position is automatically shifted by a specified correction amount. Therefore, instead of correcting the best image point at the focus position in the composition of the subject, select the composition intended by the photographer from the result of taking a picture with the focus position of the target subject shifted. An apparatus that can be used is provided, and is different from that set by the photographer to correct a focus error caused by the system as in the present invention.
Japanese Patent No. 2904595

  The problem to be solved is that the focusing accuracy of the digital AF single-lens reflex camera is required to be stricter than that of the conventional silver halide camera. Therefore, there is a limit in the conventional manufacturing method, and some of the commercialized cameras are In some cases, an error occurs in the AF operation in the combination of the interchangeable lens groups, and the focusing operation may be unsatisfactory. At present, depending on the user's request, a troublesome procedure is required to bring in correction data for the combination of the camera and lens by taking it to the manufacturer, and rewrite the ROM data of the CPU in the camera to correct the focus of the AF. .

  When the focal point of the AF operation is adjusted to the standard position of the factory and it is judged that it is better to slightly correct the focal position depending on the lens held by the user in the shipped completed camera, the user is responsible for the standard focal position. The lens was equipped with a focus position correction means that can be adjusted manually. The adjustment is an operation method performed by the user's will. After the focus correction, a warning is given, and when the lens using the correction means is detached from the camera, a reset means that automatically returns to the standard focus position is provided. I have.

  Although the focal position correcting means installed on the lens side can arbitrarily adjust the focal position, it is not always easy to correct, and it is determined that a better focused image can be obtained according to the will of the user. Because it is a correction means performed in the result, for users who feel that the inherent lens characteristics are not fully exhibited due to the characteristics of the digital camera, the characteristics can be further improved by a slight adjustment, and the user's satisfaction can get.

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

  FIG. 1 is a block diagram showing an embodiment of the apparatus of the present invention, and FIG. 2 is a flowchart for explaining the operation.

  In the center of the block diagram of FIG. 1, the lens side and the camera side are divided by a chain line, but the right camera side is a digital AF single-lens reflex camera shown by the camera body 3, and the left lens side is A system interchangeable lens represented by a photographic lens 2 is shown. A camera mount 3 is provided with a lens mount 4b at the rear of the photographic lens 2 with respect to a body mount 4a installed on the front surface with the optical axis 1 as the center. Through these, the camera body 3 and the taking lens 2 are detachable structures, and represent a system in which lenses can be exchanged. Light rays from the subject pass through the taking lens 2 around the optical axis 1, are reflected upward by the main mirror 5 installed in the camera body 3, and are guided to the eyepiece lens 7 through the pentaprism 6. Thus, at the eye level peeked from here, the finder mechanism is the same as the conventional finder mechanism in which the subject image can be visually recognized as an erect real image.

  The camera body 3 is generally composed of three sections. The photometry section for light intensity control and the distance measurement section for AF control are the same as those of conventional cameras. Instead of the silver salt film on the focal plane, an image sensor is used. A digital single-lens reflex camera is added with an image processing department that installs and electronically processes images.

  The photometry department receives a part of the subject light by the photometry element 9 installed in the vicinity of the eyepiece 7, sends the signal to the photometry calculation CPU 10, and controls the shutter 14 with the drive signal output from the driver 11 as a result of the photometry calculation. The diaphragm 13 of one photographing lens 2 is sent as a diaphragm control signal from the camera body 3 side to the driver 19 on the photographing lens 2 side, and the diaphragm driving motor 12 is driven by the output to control the diaphragm 13. Control is performed so that the subject light projected on the image sensor 8 has an optimum light amount.

  In the distance measuring department, a part of the subject light that has passed through the photographing lens 2 passes through the main mirror 5, is totally reflected downward by the sub-mirror 15, and is guided to the AF module 16 installed in the lower part. In the AF module 16, a distance measurement signal obtained from a distance measuring element 17 that is optically located in a co-relationship position with the imaging element 8 on the focal plane is sent to the distance calculation CPU 18, and the result of the distance calculation calculation is obtained. The signal is sent from the lens CPU 30 to the driver 31 while communicating with the lens CPU 30 incorporated in the photographic lens 2, and the lens drive motor 20 is driven by this output signal, thereby adjusting the focus of the photographic lens 2. The movement amount of the lens is read by the signal of the encoder 21 and controlled to the in-focus position. The distance measurement CPU 18 has a storage unit 26, and the standard for determining the focus is determined by the non-rewritable ROM 27, and the standard focal position is determined by the ROM 27. In communication with the lens CPU 30 of the photographing lens 2, the RAM 29 of the storage unit 28. By rewriting the above data, the determination criterion on the camera body 3 side can be corrected.

  In the image processing department, the image signal obtained by projecting the subject image controlled to the optimum focus in the distance measurement department and controlled to the appropriate light quantity in the photometry department on the surface of the image sensor 8 is sent to the image processing CPU 22 for image processing. The subject signal is recorded on a recording medium (not shown), and the photographing is completed. The subject image to be photographed and recorded passes through the eyepiece 7 and can be observed with an eye level finder.

  The above is the flow of the photographing operation of the digital single-lens reflex camera. In the normal AF operation with the photographing lens 2 attached to the camera body 3, the distance calculation CPU 18 uses the distance measurement signal obtained by the distance measuring element 17. The calculated focus determination is standardized from data in the ROM 27 serving as a reference of the storage unit 26, and focus control is performed according to a conventional general AF operation. However, there is dissatisfaction with the standard focusing operation of the photographic lens 2 to be mounted as described above, and a more accurate focusing operation can be obtained by slightly correcting the standard focusing determination. When the user thinks that this is the case, the data in the RAM 29 of the storage unit 28 in the lens CPU 30 is rewritten by the two focus correction operations of the + correction SW 24 and the −correction SW 25 installed on the photographing lens 2 by the user, and the reference for focus determination The correction can be performed, and + correction (front pin) and −correction (rear pin) can be performed by operating + correction SW24 and −correction SW25, respectively, with respect to the standard focus position.

  The lens focus detection SW 23 is installed in the vicinity of the lens mount 4 b in the photographing lens 2, and the signal focus correction operation is effective only when there is a sensing signal obtained by mounting the camera body 3. A small unit movement amount Δf that can be detected by the encoder 21 is one push ON of the + correction SW 24 and the −correction SW 25, and the correction amount is determined by adding the number of pushes. That is, if the number of pushes of the + correction SW 24 is m, the front pin can be corrected by mΔf from the standard in-focus position, and if the number of pushes of the −correction SW 25 is n, the rear pin can be corrected by nΔf. Both push times are subtracted (m−n) Δf, and if the result is +, the front pin is used, and if the result is −, the back pin is used.

  The focus correction performed after the photographic lens 2 is mounted is continued while the photographic lens 2 is mounted. When the lens 2 is detached from the mount 4, the correction is canceled and the standard focusing operation is reset.

  FIG. 2 is a flowchart showing the above-described series of correction operations and correction operations. To explain according to the order of this flowchart, the time when the camera is turned on and the circuit is activated is designated as START 201. The lens mounting detection SW 23 confirms the lens mounting. In 203, it is determined whether or not the camera body 3 is mounted by the lens mounting signal 202. In this case, the circuit energization is always performed. In the case of (NO), the reset signal immediately cancels the correction data in the RAM 29 of the storage unit 28 of the lens CPU 30, and the signal is communicated to the distance measurement CPU 18 on the camera body side. Then, the data is returned to the standard focusing operation data by the ROM 27. In other words, if it is determined in 203 that the lens has been removed, the routine proceeds to 204, where the standard focus position is reset to the initial setting value, and the processing returns to 203, and the camera mounting determination is repeated (YES).

  If it is determined in 203 that the photographic lens 2 is attached to the camera body 3 (YES), the AF operation 206 is started by pressing the release button 205, and the distance measurement calculation based on the distance measurement signal of the distance measuring element 17 is performed. Based on the calculation result of the CPU 18, a standard in-focus determination is made at 207. If the focus is not determined (NO), the lens CPU 30 communicates with the lens CPU 30 of the photographic lens 2, the lens drive motor 20 is rotated by the output signal from the driver 31, and the lens movement amount is determined by an encoder signal 209 that is a signal of the encoder 21. The lens drive 208 is continued while measuring and calculating. When the result of the lens drive 208 is determined as “YES” in the in-focus determination of 207, the result signal is sent to the lens CPU 30 and operated by the operation 210 of the + correction SW24 or −correction SW25 of the focus correction SW, and the number of correction operations. A determination is made at 213 as to whether or not there is a storage 211.

  If it is determined in 213 that there is no request for focus correction operation (NO), the lens drive 208 in the focusing operation stops at 214, and the drive of the distance calculation CPU 18 on the camera body 3 side is stopped. A standard in-focus position according to the data in the ROM 27 is obtained. Normally, the camera operation follows this flow, and when the release button is further depressed, the shutter is released and the shooting is completed.

  If it is determined in step 213 that there has been a focus correction operation from 210 and the RAM 29 data in the storage unit 28 has been rewritten in step 211 (YES), it is determined in step 215 whether the request is + correction or -correction. For this reason, the number m of operations of the + correction SW 24 is compared with the number n of operations of the −correction SW 25. If m is larger (YES), it is determined as + correction, and at 216, the lens moves in the + direction (front pin). Driven. The movement continues until the encoder signal 217 obtained from the encoder 21 counts (mn) times when the lens is driven. When the mn count is completed at 218 (YES), the lens drive stops at 221. In addition, it is possible to take an image at a position where the focus is corrected by Δf (mn) with respect to the standard focus. When the operations of the + correction SW 24 and the −correction SW 25 of 210 are performed and the number of operations is stored in 211, an output signal for causing the LED or the like to emit light from the driver 32 is obtained by a signal from the lens CPU 30, and a correction warning of 212 is obtained. It is designed to display. In the embodiment shown in FIG. 1, 212 is constituted by a dot array of LEDs (not shown), distributed from the center to the + side and the-side, and lit in the order of 2 lamps, 1 lamp, 2 lamps, and the amount of correction increases as the distance from the center increases. The warning is given in the lighting mode that increases.

  Next, if the value of (mn) determined at 215 is-, that is, (NO), it is determined as -correction, the lens is driven in the -direction (rear pin) at 219, and is obtained from the encoder 21 at 220. The encoder signal 217 is continued until it is determined that counting is completed (n−m) times (YES). If the result is 220 (YES), the process proceeds to 221 and the lens driving is stopped, and the photographing can be performed at the correction position as requested by correcting the focal position to the minus side by Δf (n−m). In this case as well, the correction warning display 212 appears, and the LED dot array (not shown) at the position where the warning display 33 of the photographing lens 2 is separated by −Δf (nm) from the center lights up to give a correction warning. It will be.

  As described above, this device is a focus correction device that can correct a standard in-focus position, which is an AF operation reference of a product, by a user operation based on the user's responsibility. It is not required that the operation is easy so that it will not be operated easily. In this project, it is assumed that the push switch recessed from the lens barrel surface is operated with a pointed pen tip, etc. A dial with the same surface position as the surface of the lens barrel may be used, and there are various approximation methods such as providing a mechanism for automatically returning to the correction zero position by attaching / detaching operation from the camera. When correction data is written in the RAM 29 of the storage unit 28 by a focus correction SW operation, a warning is displayed on the warning display 33 to alert the user. In addition, since it is an irregular adjustment to the last, the preset focus correction at the time of lens replacement is reset and returned to the standard, so that a correction operation not intended by the user can be avoided.

  In the combination of the main body of the system product and the accessory, the satisfaction of the user is increased by making the product that can be corrected under the responsibility of the user to the user who cares about compatibility.

1 is a block diagram of a lens and camera operating system including the present invention. The operation | movement flowchart of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Optical axis 2 Shooting lens 3 Camera main body 4a Body mount 4b Lens mount 5 Main mirror 6 Pentaprism 7 Eyepiece 8 Imaging element 9 Photometric element 10 Photometric calculation CPU
DESCRIPTION OF SYMBOLS 11 Driver 12 Aperture drive motor 13 Aperture 14 Shutter 15 Sub mirror 16 AF module 17 Distance measuring element 18 Distance calculation CPU
20 Lens drive motor 21 Encoder 22 Image processing CPU
23 Lens mounting detection SW
24 + Correction SW
25-Correction SW
26 storage unit 27 ROM
28 storage unit 29 RAM
30 Lens CPU
31 Driver 32 Driver 33 Warning indication

Claims (3)

  In a system interchangeable lens that can be used for both conventional silver salt film AF single-lens reflex cameras and digital AF single-lens reflex cameras, the reference position can be manually shifted from the AF focus adjustment reference position that is set at the factory. An AF system interchangeable lens comprising: a correction means that can be changed by a photographer at a best focus position determined by the photographer after the system interchangeable lens is mounted on the AF single-lens reflex lens. Focus correction device.   The best focus position correction means is installed in the AF system interchangeable lens, and includes two push switches for + correction and -correction for the best focus correction, and the number of push times in which one push of the push switch is moved by a minute unit. The correction amount can be determined by integration, and addition and subtraction can be performed according to the number of pushes of the + correction push switch and the −correction push switch, and the correction means is effective after the camera body is completely mounted. 2. The focus correction apparatus for an AF type system interchangeable lens according to claim 1, wherein the focus correction apparatus is reset to a focus adjustment reference position at the time of factory shipment by detaching the lens from the camera body.   A focus correction apparatus for an AF type system interchangeable lens, characterized in that a warning can be given to a photographer by a warning display means installed on the surface of a lens barrel when correction is performed by the best focus position correction means.

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