JP4582142B2 - interchangeable lens - Google Patents

Description

  The present invention detects a defocus amount corresponding to a deviation amount between an imaging position of a subject image and a planned imaging plane, and determines whether or not the defocus amount is within the in-focus certification range. The present invention relates to an interchangeable lens that supplies an in-focus certification range to a camera system having an apparatus.

  In general, in a camera that performs focus determination at the time of focusing, the focus recognition range is determined based on the depth of focus.

  FIG. 10 is a conceptual diagram of a conventional in-focus certification range.

  As shown in the figure, when the light incident through the photographing optical system 100 having the effective aperture D is focused at the focal point a, a confusion circle having a diameter M is formed on the planned imaging surface (surface equivalent to the film surface) 101. It is formed. Here, the defocus amount b corresponds to the amount of deviation between the focal point a and the planned imaging plane 101, and the focal length f corresponds to the distance from the center of the photographing optical system 100 to the focal point a.

  In the figure, since the ratio between the effective aperture D and the focal length f coincides with the ratio between the diameter M of the circle of confusion and the defocus amount b, the defocus amount b is “(focal length f / effective aperture D) × It can be indicated by the diameter M of the circle of confusion. Here, since “focal length f / effective aperture D” corresponds to F value on a one-to-one basis, defocus amount b can be obtained by “F value × diameter M of circle of confusion”.

  By the way, the depth of focus is expressed by a defocus amount in which the diameter of the circle of confusion is equal to or smaller than the diameter of the allowable circle of confusion. In general, the diameter of the permissible circle of confusion is set to about 1/1000 to 1/1500 of the diagonal length of the screen, and in particular, the diameter of the permissible circle of confusion for a 35 mm film is set to 1/30 mm. Accordingly, the depth of focus can be approximated by “F value × (1/30)”.

  Conventionally, in-focus determination has been performed by using such a depth of focus as the in-focus recognition range.

  For example, Japanese Patent Application Laid-Open No. 57-185423 discloses a technique for realizing autofocus by changing the focus certification range according to the set F value and performing focus determination.

On the other hand, the focus determination is not limited to autofocus, but is also performed with a focus aid that performs focus display as shown in FIG. Even in such a focus aid, it is possible to perform in-focus determination based on the in-focus recognition range at the set F value.
JP-A-57-185423

  However, in an actual photographing optical system, the influence of aberration cannot be ignored, and it is difficult to uniquely determine the depth of focus according to the F value.

  Further, in various types of focus determination by the photographing optical system, the degree of sharpness of the optical image formed on the planned imaging surface varies greatly depending on the aberration characteristics of each photographing optical system. Therefore, even if the defocus amount is the same, the images are not always formed at the same level.

  Therefore, in autofocus, in the focus determination using the focus recognition range as in the past, it is accurately determined whether or not the state of the optical image formed on the planned image formation surface is at a good level. I couldn't.

  Further, in the focus aid, a finder image is displayed in the open state even if the focus determination is performed within the focus certification range for the F value (set F value) set by narrowing down. For this reason, when a lens whose focal point is moved as the aperture is reduced is used, even if the finder image is in the focused state, the focus aid display does not display the focused state and the operation feeling is poor.

  SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to provide an interchangeable lens that supplies a focus recognition range in which focus determination can be performed accurately.

  FIG. 1 is a principle block diagram of an in-focus determination device used in the present invention.

  This in-focus determination device is detected by a detecting means 10 for detecting a defocus amount corresponding to a deviation amount between an imaging position of a subject image by a photographing optical system and a planned imaging surface of the photographing optical system, and detected by the detecting means 10. In the in-focus determination apparatus including the determination unit 12 that determines whether or not the defocus amount is within the in-focus determination range, the determination unit 12 determines the in-focus determination according to the imaging performance of the photographing optical system. Make a decision based on the range.

  FIG. 2 is a block diagram showing the principle of another in-focus determination apparatus used in the present invention.

  The focus determination apparatus in FIG. 2 performs the selection operation between the automatic focus mode in which focusing is automatically performed and the manual focus mode in which focusing is performed based on an instruction by manual operation in the focus determination apparatus in FIG. A receiving mode setting unit 14 and a focusing notification unit 16 for notifying the outside of whether or not the focus state is achieved based on the determination made by the determination unit 12, and the determination unit 12 via the mode setting unit 14 When the manual focusing mode is selected, the focus recognition range related to the best image plane position at the open F value, and the focus recognition range related to the best image plane position at the F value narrowed down by a predetermined number of steps, The range that includes is the focus certification range.

  FIG. 3 is a principle block diagram of the camera system used in the present invention.

  This camera system includes a storage unit 18 that stores a predetermined in-focus certification range according to the imaging performance of the photographing optical system in the camera system having the in-focus determination device of FIG. 12 determines whether or not the defocus amount detected by the detection unit 10 is within the in-focus determination range stored in the storage unit 18.

  In this camera system, the storage unit 18 stores a plurality of focus certification ranges in association with the F value, the focus position, or the zoom position, and the determination unit 12 stores the F value, the focus position, or the zoom position of the photographing optical system. Based on this, it is possible to acquire the in-focus recognition range by searching the storage unit and determine whether the defocus amount detected by the detection unit 10 is within the in-focus determination range.

  FIG. 4 is a principle block diagram of another camera system used in the present invention.

  The camera system of FIG. 4 includes the identification information acquisition unit 20 that acquires identification information indicating the type of the imaging optical system from the imaging optical system in the camera system of FIG. 3, and the storage unit 18 includes the identification information of the imaging optical system. A plurality of in-focus recognition ranges are stored in association with each other, and the determination unit 12 acquires the in-focus approval range by searching the storage unit based on the identification information of the photographing optical system acquired by the identification information acquisition unit 20. Then, it is determined whether or not the defocus amount detected by the detection means 10 is within the in-focus certification range.

Figure 5 is a principle block diagram of the invention according to claim 1 and 2.

The interchangeable lens according to claim 1, the imaging optical system 22, the defocus amount MTF value as a predetermined proportion or more with respect to the best value of the MTF is Ru is secured against defocus amount of the photographing optical system 22 It is characterized by comprising storage means 24 for storing the range as an in-focus authorized range and range supply means 26 for supplying the in- focus authorized range stored in the storage means 24 to the in-focus determining means of the camera .

The interchangeable lens according to claim 2 is the interchangeable lens according to claim 1, wherein the storage unit 24 stores a plurality of in-focus recognition ranges in association with the F value, the focus position, or the zoom position of the photographing optical system 22. Then, the range supply means 26 selects a focus certification range based on the F value, focus position or zoom position of the photographing optical system 22, and supplies the focus certification range to the camera focus judgment means. And

(Function)
In the interchangeable lens according to the first aspect of the present invention, the storage unit 24 stores a focus certification range determined in advance according to the imaging performance of the photographing optical system 22. The range supply unit 26 supplies the in-focus determination range stored in the storage unit 24 to the in-focus determination unit of the camera .

  Therefore, in a camera equipped with such an interchangeable lens, it is possible to perform in-focus determination flexibly corresponding to a difference in imaging performance of the photographing optical system 22.

In the interchangeable lens according to the second aspect of the invention, the storage unit 24 stores a plurality of in-focus authorized ranges in association with the F value, the focus position, or the zoom position of the photographing optical system 22. The range supply unit 26 selects a focus certified range from the storage unit 24 based on the F value, the focus position, or the zoom position of the photographing optical system 22, and the focus certified range searched in this way is used as a camera focus determination. Supply to the means .

  Therefore, since the in-focus recognition range can be defined by various conditions, the accuracy of the in-focus determination can be reliably improved in a camera equipped with such an interchangeable lens.

As described above, according to the first aspect of the present invention, in a camera equipped with such an interchangeable lens, it is possible to perform in-focus determination flexibly corresponding to a difference in imaging performance of the photographing optical system.

Further, in the invention described in claim 2 , since the in-focus recognition range can be defined by various conditions, the accuracy of the in-focus determination is reliably improved in a camera equipped with such an interchangeable lens. Can do.

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

Since the present invention is characterized in that the focus determination is performed based on the focus recognition range determined according to the imaging performance of the photographing optical system, the focus determination range will be described at the beginning of each embodiment. . The operation of each embodiment will be described using an interchangeable lens single-lens reflex camera system.
(First embodiment)
FIG. 6 is a conceptual diagram of the in-focus recognition range stored in the interchangeable lens according to the first embodiment of the present invention.

  In the figure, the vertical axis indicates the value of MTF (Modulation Transfer Function), and the horizontal axis indicates the defocus amount. Curves α and β show an outline of the MTF value with respect to the defocus amount in a state where the aperture is opened in two lenses having different MTF characteristics.

  In general, it is possible to determine whether or not the state of the optical image formed on the planned imaging plane is at a satisfactory level by determining whether or not the MTF value indicates a favorable value.

  Therefore, in the present embodiment, the in-focus certification range is determined based on the defocus amount that can maintain a good value of MTF (here, 80% of the best value for simplicity).

  For example, in FIG. 6, assuming that the threshold for determining the quality of MTF is given by the straight line g, in the case of a lens having the MTF characteristic of the curve α, the defocus amount corresponding to the point A to the point B (range C ) Is the focus certification range. Further, in the case of a lens having the MTF characteristic of the curve β, the defocus amount (range F) corresponding to the point D to the point E becomes the in-focus certification range.

  Note that the in-focus certification range varies depending on the change in MTF characteristics caused by the difference in lens aberration, focus position, and zoom position, even if the F value is the same.

  Therefore, in this embodiment, a plurality of MTF characteristics are obtained in advance by actual measurement or optical simulation according to the F value, the focus position, and the zoom position for each lens, and the MTF value can be maintained at 80% of the best value. The focus amount is set as the in-focus certification range.

  FIG. 7 is a functional block diagram of the camera system equipped with the interchangeable lens according to the first embodiment of the present invention.

  In the figure, an interchangeable lens 31 is attached to the camera body 30 by a mount mechanism (not shown).

  A focus lens group 32 and a zoom lens group 33 are arranged in the interchangeable lens 31, and a main mirror 34 and a sub mirror 35 are arranged in the camera body 30 on the optical axes of the focus lens group 32 and the zoom lens group 33. The

  In the camera body 30, a finder screen 37 is disposed at a position mirrored with the film surface 36 in the reflection direction of the main mirror 34, and a focus detection unit 38 is disposed in the reflection direction of the sub mirror 35. The output of the focus detection unit 38 is connected to the body side control unit 39.

  The casing of the interchangeable lens 31 is provided with a focus ring 40, a zoom ring 41, and an aperture ring 42.

  Further, in the interchangeable lens 31, a lens side control unit 43, and a focus position detection unit 44, a lens drive unit 45, a zoom position detection unit 46, and an F value detection unit 47 connected to the lens side control unit 43 are provided. Is provided.

  The lens side control unit 43 includes a data selection unit 48, a memory 49, and a communication unit 50, and is connected to the body side control unit 39 via the communication unit 50.

  In the present embodiment, the memory 49 stores information indicating the type and characteristics of the lens and, as described above, a plurality of in-focus recognition ranges corresponding to the set F value, the focus position, and the zoom position. Is stored.

  Further, regarding the correspondence between the principle block diagram shown in FIGS. 1, 3 and 5 and the functional block diagram shown in FIG. 7, the detecting means 10 calculates the defocus amounts of the focus detection unit 38 and the body side control unit 39. Corresponding to the function, the determination unit 12 corresponds to the function of performing the focus determination of the body side control unit 39, the storage units 18 and 24 correspond to the memory 49, the photographing optical system 22 includes the focus lens group 32 and Corresponding to the zoom lens group 33, the range supply means 26 corresponds to the data selection unit 48 and the communication unit 50.

  Hereinafter, the operation of the camera system including the interchangeable lens according to the first embodiment of the present invention will be described with reference to FIG.

  In the interchangeable lens type single-lens reflex camera system shown in FIG. 7, the focus lens group 32 moves based on the operation of the photographer with respect to the focus ring 40 or the driving of the lens driving unit 45, and the zoom lens group 33 captures with respect to the zoom ring 41. Move based on the user's operation.

  The focus position and the zoom position changed by the movement of the focus lens group 32 and the zoom lens group 33 are detected by the focus position detection unit 44 and the zoom position detection unit 46, and are given to the lens side control unit 43. .

  Further, the light beam incident on the interchangeable lens 31 reaches the main mirror 34 via the focus lens group 32 and the zoom lens group 33. The light beam reaching the main mirror 34 is branched and guided to the finder screen 37, reflected through the sub mirror 35, and guided to the focus detection unit 38.

  When the release button (not shown) is half-pressed, the focus detection unit 38 divides the light beam that has reached through the sub-mirror 35 and outputs information on a set of images formed by the divided light beam to the body side control unit. 39.

  When such a set of images is given from the focus detection unit 38, the body side control unit 39 calculates the defocus amount based on the positional relationship between the images.

  On the other hand, the lens side control unit 43 acquires the F value (corresponding to the set F value) set by the photographer by operating the aperture ring 42 via the F value detection unit 47. Further, the lens side control unit 43 sends the set F value acquired in this way and the focus position and zoom position given from the focus position detection unit 44 and the zoom position detection unit 46 to the data selection unit 48 as described above. Supply.

  The data selection unit 48 refers to the memory 49 to select and read the in-focus authorized range corresponding to the set F value, the focus position, and the zoom position.

  The in-focus determination range read in this way is given to the body side control unit 39 via the communication unit 50.

  When the in-focus recognition range is given, the body-side control unit 39 determines whether or not the defocus amount calculated as described above is within the in-focus approval range.

  Therefore, in the present embodiment, since the optimum focus recognition range can be selected according to the set F value, the focus position, and the zoom position, the focus determination can be performed accurately.

In addition, since selection of the in-focus authorized range is performed within the interchangeable lens 31, the accuracy of in-focus determination can be easily improved without changing the configuration of the camera body.
(Second embodiment)
FIG. 8 is a conceptual diagram of the in-focus recognition range stored in the interchangeable lens according to the second embodiment of the present invention.

  In the figure, a curve γ indicates an outline of the MTF value with respect to the defocus amount in a state where the aperture is opened, and a straight line m1 indicates a threshold value when determining the quality of the MTF as in the above-described embodiment.

  A straight line n indicates the best image plane position at a set F value narrowed down by a predetermined number of steps (here, two steps for simplicity) from the open F value, and a curve δ indicates the best image. The outline of the value of MTF with respect to the defocus amount in a surface position is shown. Further, the straight line m2 indicates a threshold value when determining the quality of the MTF at the set F value.

  In the present embodiment, in a lens in which the best image plane position changes by narrowing down, a focus recognition range (range J) at the open F value and a focus recognition range (at the set F value narrowed by two steps from the open F value) (range J). The defocus amount (range L) including the range K) is set as the in-focus certification range.

  By the way, even when the same number of steps is narrowed down, the amount of change in the best image plane position differs depending on the lens. For this reason, in the present embodiment, the MTF characteristics for the two F values described above for each lens are obtained in advance by actual measurement or simulation, and a plurality of in-focus determination ranges corresponding to each lens are determined.

  FIG. 9 is a functional block diagram of a camera system equipped with an interchangeable lens according to the second embodiment of the present invention.

  In the figure, the same functions as those in the block diagram shown in FIG. 7 are denoted by the same reference numerals, and the description thereof is omitted here.

  The difference between the configuration of the present embodiment and the above-described embodiment is that the body side control unit 51 and the lens side control unit 52 are replaced with the body side control unit 39 and the lens side control unit 43 shown in FIG. And a focus mode select dial 53 is newly provided in the housing of the camera body 30.

  In FIG. 9, the body side control unit 51 includes a data selection unit 54, a body side memory 55, and a body side communication unit 56, and the lens side control unit 52 includes a lens side memory 57 and a lens side communication unit 58. The body side control unit 51 and the lens side control unit 52 are connected via a body side communication unit 56 and a lens side communication unit 58.

  Here, the lens-side memory 57 stores identification information indicating the lens type, and the body-side memory 55 stores the in-focus certification range determined as described above for the lens type, the focus ring 40, the zoom ring 41, and the aperture. Assume that it is stored in association with the set position of the ring 42.

  For the correspondence between the principle block diagrams shown in FIGS. 1, 2, and 4 and the functional block diagram shown in FIG. 9, the detection means 10 calculates the defocus amounts of the focus detection unit 38 and the body side control unit 51. Corresponding to the function, the determination means 12 corresponds to the function of performing the focus determination of the body side control unit 51, the mode setting means 14 corresponds to the focus mode select dial 53, and the focus notification means 16 corresponds to the finder screen. 37 corresponds to a focus display unit (not shown) provided near 37, the storage unit 18 corresponds to the body side memory 55, and the identification information acquisition unit 20 corresponds to the body side communication unit 56.

  Hereinafter, the operation of the camera system including the interchangeable lens according to the second embodiment of the present invention will be described with reference to FIG.

  In the interchangeable lens type single-lens reflex camera system shown in FIG. 9, the lens side control unit 52 performs identification information indicating the type of the lens stored in the lens side memory 57 and each operation of the interchangeable lens 31 via the lens side communication unit 58. Member position information (corresponding to information output from the focus position detection unit 44, zoom position detection unit 46, and F value detection unit 47) is given to the body side control unit 51.

  When the body-side control unit 51 acquires such identification information and position information via the body-side communication unit 51, the body-side control unit 51 gives the data selection unit 54. The data selection unit 54 refers to the body side memory 55 to select and read the in-focus authorized range corresponding to the identification information and the position information.

  The focus detection unit 38 divides the light beam that has reached through the sub-mirror 35 in the same manner as in the above-described embodiment, and gives information on a set of images formed by the divided light beam to the body-side control unit 51.

  When such a set of images is given from the focus detection unit 38, the body-side control unit 51 calculates the defocus amount and the defocus direction based on the positional relationship between the images as in the above-described embodiment.

  Further, the body-side control unit 51 determines the state of the focus mode select dial 53, and when the manual focus mode is selected, the body-side memory 55 represents the focus authorization range as shown in FIG. While reading the data, it is determined based on the data whether the defocus amount calculated as described above is within the in-focus certification range. Furthermore, based on such determination, the body-side control unit 51 performs a focus display as shown in FIG. 11 in the viewfinder.

  That is, in the present embodiment, in the manual focusing mode, the focus recognition range can be widened based on the change in the best image plane position due to the narrowing down (corresponding to the range L in FIG. 8). The situation where the focus mark 102 does not light up even though the image is in focus can be reliably reduced.

  In this embodiment, the in-focus certification range is stored in the body-side memory 55 and the in-focus certification range is selected in the camera body 30, but the data selection unit 54 is connected to the lens side as in the above-described embodiment. By providing the controller 52, the in-focus authorized range may be selected in the interchangeable lens 31.

  Further, in each of the above-described embodiments, the defocus amount that can maintain a good MTF value is used in determining the in-focus certification range. However, a defocus amount that can maintain a good OTF value and a high Naach value is used. A focus amount may be used.

  Further, in each of the above-described embodiments, the imaging performance is evaluated based on the MTF characteristics to determine the in-focus certification range. Such an imaging performance evaluation is performed using the focus lens group 32 and the zoom lens. This may be performed based on the aberration characteristics of the group 33 or the like.

It is a principle block diagram of the focus determination apparatus used by this invention. It is a principle block diagram of the other focus determination apparatus used by this invention. It is a principle block diagram of the camera system used by the present invention. It is a principle block diagram of the other camera system used by this invention. It is a principle block diagram of the interchangeable lens which concerns on this invention. It is a conceptual diagram of the focus certification | authentication range which the interchangeable lens by 1st embodiment of this invention memorize | stores. 1 is a functional block diagram of a camera system equipped with an interchangeable lens according to a first embodiment of the present invention. It is a conceptual diagram of the focus certification | authentication range which the interchangeable lens by 2nd embodiment of this invention memorize | stores. It is a functional block diagram of the camera system which mounted | wore with the interchangeable lens by 2nd embodiment of this invention. It is a conceptual diagram of the conventional focus certification | authentication range. It is a figure which shows the example of a focus display. It is a figure which shows the change of the focus state by narrowing down.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Detection means 12 Determination means 14 Mode setting means 16 Focus notification means 18, 24 Storage means 20 Identification information acquisition means 22, 100 Imaging optical system 26 Range supply means 30 Camera body 31 Interchangeable lens 32 Focus lens group 33 Zoom lens group 34 Main mirror 35 Sub mirror 36, 101 Plane imaging plane 37 Finder screen 38 Focus detection unit 39, 51 Body side control unit 40 Focus ring 41 Zoom ring 42 Aperture ring 43, 52 Lens side control unit 44 Focus position detection unit 45 Lens drive unit 46 Zoom position detection unit 47 F value detection unit 48, 54 Data selection unit 49 Memory 50 Communication unit 53 Focus mode select dial 55 Body side memory 56 Body side communication unit 57 Lens side memory 58 Lens side communication unit 10 Focus mark 103 and 104 triangle mark

Claims (2)

Photographic optics,
Storage means for storing a defocus amount in the range of MTF value to be predetermined proportions or Ru is reserved for the best values of the MTF for defocus amount of the photographing optical system as a focusing accreditation range,
An interchangeable lens comprising: a range supply unit that supplies the in-focus determination range stored in the storage unit to a focus determination unit of a camera . The interchangeable lens according to claim 1,
The storage means stores a plurality of in-focus detection ranges in association with the F value, the focus position, or the zoom position of the photographing optical system,
The range supply means selects an in-focus authorized range based on an F value, a focus position, or a zoom position of the photographing optical system, and supplies the in-focus authorized range to an in-focus determination means of the camera. Interchangeable lens.

Images