JP2730036B2 - Focus detection system of interchangeable lens camera and interchangeable lens used for the same - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial Application Field) The present invention projects auxiliary light having a predetermined wavelength toward a subject, and reflects a reflected light beam from the subject in a region outside the optical axis of the interchangeable lens. TECHNICAL FIELD The present invention relates to a focus detection system of an interchangeable lens camera that detects a focus of a subject by using a camera, and an interchangeable lens used in the focus detection system.

(Prior Art) When projecting auxiliary light having a predetermined wavelength other than visible light toward a subject and performing focus detection on the subject based on the reflected light flux, a focus detection element ( A certain shift occurs between the image forming position of the subject and the film surface position indicated by the defocus amount detected by the light receiving unit and the focus detecting unit. Japanese Patent Application Laid-Open Nos. 58-208732 and 58-208732 disclose a method of correcting this deviation (correction amount) with respect to the detected defocus amount to accurately form a subject image on a film surface position. It is already well known, for example, from JP-A-59-208512. That is, the correction amount of the defocus amount is stored in the storage means in the lens, transmitted to the camera body side as needed, and when the focus is detected by projecting the infrared light as the auxiliary light, the correction is performed based on the correction amount and the object is corrected. In this case, an accurate defocus amount is obtained.

(Problems to be Solved by the Invention) However, all of the conventionally known techniques are corrections for a case where a subject located on the optical axis of the interchangeable lens is detected. Since light from a subject located outside the optical axis of the interchangeable lens enters the optical axis of the interchangeable lens obliquely,
The aberration performance of the lens (the light flux from the subject near the optical axis is incident almost parallel to the optical axis) is different from the conventional case of detecting the subject on the optical axis. Therefore, the conventional correction amount is used. Cannot perform highly accurate focus detection.
That is, different correction amounts are required for focus detection of a subject located in a different area on the shooting screen.

Therefore, an object of the present invention is to provide a focus detection system for an interchangeable lens camera that can perform highly accurate focus detection when a focus detection is performed by projecting auxiliary light to a subject located outside the optical axis of the interchangeable lens. And an interchangeable lens used in the focus detection system.

(Means for Solving the Problems) In order to achieve the above object, a focus detection system for an interchangeable lens camera according to the present invention uses a light flux from a subject located in a region outside the optical axis of the interchangeable lens to output a pupil of the interchangeable lens. Dividing into a pair of light beams that pass through different areas of the surface, an optical unit that forms a pair of light images from the light beams, a light receiving unit that receives the pair of light images, and a subject based on an output of the light receiving unit. Focus detection means for performing focus detection and calculating the defocus amount of the interchangeable lens, and a correction amount for correcting the defocus amount when performing focus detection on a subject on the optical axis to perform the first correction are stored. A first correction amount storage unit that stores a correction amount for correcting a defocus amount when performing focus detection on a subject located outside the optical axis in order to perform the first correction. Storage means, and A third correction amount storage unit that stores a correction amount for correcting a defocus amount when performing focus detection on a subject on the optical axis in order to perform a second correction different from the first correction; A fourth correction amount storage unit that stores a correction amount when focus detection is performed on a subject located in an area outside the optical axis in order to perform a second correction different from the first correction; At the time of focus detection in step (1), in addition to the correction amount in the first correction amount storage unit, the second
A fourth determining means for determining which correction amount among the correction amounts of the correction amount storage means is to be used, and a correcting means for correcting the defocus amount based on the stored correction amount according to the determination by the determining means. Lens driving means for driving the interchangeable lens according to the corrected defocus amount obtained by the correction means.

Further, the interchangeable lens of the present invention used in the above-described focus detection system exchanges light based on a pair of light fluxes from a subject in an area outside the optical axis of the interchangeable lens that has passed through different areas of the exit pupil plane of the interchangeable lens. Calculate the defocus amount of the lens,
An interchangeable lens used in a focus detection system of an interchangeable lens camera that corrects the defocus amount and drives the interchangeable lens according to the corrected defocus amount.
First correction amount storage means for storing a correction amount for correcting a defocus amount when focus detection is performed on an object on the optical axis in order to perform correction, and light correction for performing first correction. A second correction amount storage unit that stores a correction amount for correcting a defocus amount when focus detection is performed on an object located in an off-axis region, and a second correction unit that performs a second correction different from the first correction. A third correction amount storing means for storing a correction amount for correcting a defocus amount when a focus on a subject on the optical axis is detected, and a second correction different from the first correction. And a fourth correction amount storage unit that stores a correction amount when focus detection is performed on a subject located in a region outside the optical axis.

(Operation) According to the above configuration, the correction of the defocus amount is performed based on the correction amount stored in the first correction amount storage unit and the correction amount stored in the second, third, and fourth correction amount storage units. The correction is performed based on one or more correction amounts determined to be used by the determination unit.

(Example) Hereinafter, an example of the present invention will be described with reference to the drawings.

FIG. 1 is a block diagram showing the overall circuit configuration of one embodiment of the present invention. In FIG. 1, contact groups (711) to (715) provided on a mount (7) are provided between a circuit ( 1 ) in the camera body and a circuit ( 6 ) in the taking lens.
They are electrically connected by (721) to (725).

(100) is a control circuit for controlling this system (hereinafter referred to as a control CPU).
It operates under the direction of PU (100). (1
0) is the control CPU (100) and the circuit in the taking lens ( 6 )
Power supply for supplying a constant voltage to the

Reference numeral 310 denotes a photometric circuit, which is a photometric photoelectric conversion amount (equivalent to a subject luminance value) by a photometric element (not shown) that performs TTL photometry.
A / D-converts the information about subject brightness BV (to be exact, BV
−AVo: AVo is the control CPU as the release aperture of the taking lens)
Send to (100).

An exposure control circuit (320) controls an aperture mechanism (not shown) of the photographing lens and a shutter mechanism (not shown) of the camera based on a command from the control CPU (100).

A focus detection / control circuit (330) includes a focus detection circuit (not shown) and a lens drive control circuit (not shown).

Reference numeral 340 denotes a display circuit for displaying photographing information such as an exposure mode of the camera, an exposure control value (aperture value and shutter speed value), a frame counter value, and focus / non-focus.

An auxiliary light circuit (350) is turned on when focus detection is not possible under visible light. The auxiliary light circuit built into the camera body has already been filed by the present applicant in Japanese Patent Application No.
As filed in 141538.

(360) is a film sensitivity information circuit, which is read from the film cartridge of the film loaded in the camera.
Controls film sensitivity information based on DX code.
Send to 0).

(112) is a switch (SW1) which is closed by pressing a release button (not shown) to the first stage, and (114) is a switch which is closed by pressing the release button further deeper than the first stage to the second stage. The switch (SW2) to be formed.

The oscillation circuit (370) supplies a pulse to the control CPU (100).

Next, the mounting section (7) will be described. The mount section (7) includes a camera body side mount (71) and a photographing lens side mount (72). In this embodiment, five pairs of electrical contacts (711) to (715) and (721) to (721) are provided. 725) is provided so that serial communication can be performed between the camera body and the lens by the circuit connection described below. The control CPU (100) in the camera body drives the serial input / output clock output terminal Sck (102), the input terminal Sin (103) that reads the input data from the lens serially, and the driving lens internal circuit ( 6 ). , The contact (712) of the body side mount part is connected to the clock output terminal Sck (102), the mount contact (713) is connected to the input terminal Sin (103), and the mount contact ( 7
14) are connected to the output terminals CS (104), respectively.

The contact (711) is connected to the power supply (10) via a short-circuit protection resistor (14), and the mounting contact (715)
Is grounded to the ground line of the circuit ( 1 ) in the camera body.

Now, it is assumed that the photographing lens is a zoom lens. The zoom encoder (61) encodes a signal ΔZ corresponding to a zoom operation, that is, a focal length setting operation into three bits and outputs the signal.
The decoder (62) is a clock output terminal Sc of the control CPU (100).
The clock pulse from k (102) is counted and decoded. The addressing circuit (63) is
1) and a signal from the decoder (62) is selected, and the address of a read-only memory (64... In the ROM (64), unique information regarding the photographing lens in which the ROM (64) is mounted is stored in advance for each address. When the address of the ROM (64) is designated by the address designating circuit (63), the information stored at that address is output in parallel from the ROM (64). P
The / S conversion circuit (65) converts the parallel signal sent from the ROM (64) into a serial signal, and inputs the input terminal of the control CPU (100) via the mount contacts (723) and (713).
Output to Sin (103).

The constant voltage Vcc is supplied to the circuit (6) in the taking lens via a mount contact (721), and is connected to an earth line via a mount contact (725).

FIG. 2 shows three input / output terminals Sck (102), Sin (103), and CS (104) in the control CPU (100) shown in FIG. 1 in detail.

A high enable circuit is connected to the output terminal Sck (102), and the serial port control register (SCKC)
While the signal is high, a clock pulse is output from the body side to the lens side. The serial counter (120) is 1
This is a 3-bit counter for counting clock pulses of 8 bytes. Serial counter (120)
Counts one byte (eight) clock pulses, and generates an interrupt signal (INT) to the serial counter (120) control CPU (100).

The input terminal Sin (103) is connected to the serial register (121), and one bit at a time according to the clock pulse.
Data sent from a specific address of the ROM (64) is temporarily stored in the serial register (121). The 8-bit data at a specific address of the ROM (64) held in the serial register (121) is transmitted to the random access memory in the body by an interrupt signal generated by the serial counter (120).
Stored in memory (hereinafter referred to as RAM).

Next, FIG. 3 shows an exploded perspective view of a schematic configuration of the optical device for focus detection used in the present invention.

In FIG. 3, TL ₁ and TL ₂ are photographing lenses, and the photographing lenses TL ₁ and TL ₂ each have a distance P from a predetermined image forming plane FP.
_Z1 and _PZ2 ( _PZ1 < _PZ2 ) (hereinafter, this distance is referred to as an exit pupil distance). And the planned image plane
A field mask FM is arranged near the FP. The center of the field mask FM provided a rectangular opening E ₀ of Horizontal, whereas, is provided with a rectangular opening Eo _1, Eo ₂ vertically long on both sides.
The light beams that have passed through the rectangular openings Eo, Eo ₁ and Eo ₂ of the field mask FM pass through condenser lenses Lo, Lo ₁ and Lo ₂ and are focused.

The re-imaging lens plate L includes a pair of re-imaging lenses L ₁ and L ₂ arranged in the center in the horizontal direction, and a pair of re-imaging lenses L ₃ , L ₄ and L arranged in the vertical direction on both sides. _5, it has a L _6. The re-imaging lens L ₁ ~L ₆ are all made of the same radius of curvature of the plano-convex lens. The aperture mask AM has a re-imaging lens L ₁
The aperture openings A _{1 to} A ₆ are provided at positions corresponding to L ₆ . The aperture mask AM is disposed immediately before the re-imaging lens plate L, and is in close contact with the flat portion of the re-imaging lens plate L.

The CCD line sensors Po are arranged horizontally in the center of the substrate, and the CCD line sensors Po ₁ and Po ₂ are arranged vertically on both sides of the substrate. The arrangement direction of the imaging lens pair is made to be the same as the direction of the CCD line sensor. Each of the CCD line sensors Po, Po ₁ , and Po ₂ has first and second two light receiving element arrays, and two re-imaged on the CCD line sensor by the re-imaging lens pair. The images are separately photoelectrically converted. Block AF surrounded by a dotted line in the figure
4 shows an (autofocus) sensor module.

The focus detection optical device having the above configuration detects the focus position as follows. Off-axis distance measuring luminous flux from a subject in an area off the optical axis of the photographing lens TL including the principal rays l ₃ and l ₄ ,
It passes through the rectangular opening Eo ₁ and incident on the field mask FM away from the optical axis at a predetermined angle with respect to the optical axis and incident on the condenser lens Lo _1. Off-axis distance light beam incident on the condenser lens Lo ₁ is focused with bent toward the optical axis by a condenser lens Lo _1, the throttle opening A ₃ of the diaphragm mask AM, A ₄ and through re-imaging lens plate L Are incident on the re-images L ₃ and L ₄ . Re-imaging lens L _3, off-axis distance measuring light beam incident on the L ₄ are, C by the re-imaging lens L _3, L ₄
It is focused to the CD line sensors Po _1, the CCD line sensor Po
_A pair of images is re-imaged on ₁ . Similarly, the beam for off-axis distance measurement including the principal rays l ₅ and l ₆ is incident on the field mask FM so as to be away from the optical axis at the above-mentioned predetermined angle, and has a rectangular opening Eo ₂ , a condenser lens Lo ₂ , through the opening a _5, a ₆ and the re-imaging lens L _5, L ₆ diaphragm is focused onto the CCD line sensor Po _2, a pair of image is re-imaged on the CCD line sensor Po _2.

On the other hand, the luminous flux for distance measurement on the optical axis from the subject in the area including the optical axes of the imaging lens TL including the principal rays l ₁ and l ₂ includes a rectangular opening Eo on the optical axis, a condenser lens Lo, and an aperture opening. After passing through A ₁ and A ₂ and the re-imaging lenses L ₁ and L ₂ , the above CCD line sensor Po
And a pair of images are re-formed on the CCD line sensor Po. Then, the CCD line sensor Po, Po ₁ and Po focal position detection for the photographing lens TL ₁ and TL ₂ of the object by determining the position of the image of the pair of re-imaging of the three pairs tied on ₂ Is done.

Speaking of correspondence with the viewfinder inside view shown in FIG. 4, the CCD line sensor Po is in the on-axis focus detection area Fa, the CCD line sensor Po ₁ is in the off-axis focus detection area Fa ₁ , and the CCD line sensor Po ₂ respectively correspond to the optical axis outside the focus detection area Fa ₂ is.

A ₁₁ , A ₂₁ , A ₃₁ , indicated by broken lines on the photographing lens TL ₁
A ₄₁ , A ₅₁ and A ₆₁ and A shown by a broken line on the taking lens TL _2
12 , A ₂₂ , A ₃₂ , A ₄₂ , A ₅₂ and A ₆₂ are the aperture openings A ₁ , A ₂ , A ₃ , A ₄ , A ₅ and A ₆ of the aperture mask AM, respectively.
Shooting lens T by condenser lenses Lo, Lo ₁ and Lo ₂
Shows an image when it is back-projected onto the L ₁ and the photographing lens TL _2.
In other words, it indicates the range in which the light beam for distance measurement passing through the aperture openings A ₁ , A ₂ , A ₃ , A ₄ , A ₅ and A ₆ passes through the imaging lenses TL ₁ and TL ₂ . Therefore, this back projection imaging A ₁₁ , A ₂₁ , A ₃₁ , A
_41, A ₅₁ and A ₆₁ or _{A 12, A 22, A 32} , A 42, A 52 and A
_62, if Osamu' in the opening of the photographing lens TL ₁ or TL _2, CCD line sensors Po, the light beam incident on the Po ₁ and Po ₂ is, eclipsed by the pupil of the photographing lens TL ₁ or TL ₂ And high focusing accuracy can be obtained.

Here, in any case, the CCD line sensor P
The fact that the off-axis distance measuring light beam incident on o ₁ and Po ₂ is not vignetted with respect to the pupil of the photographing lens means that, as described above, the principal rays l ₃ and l of the off-axis distance measuring light beam _4, l _5, the l _6, the distance y is largely from the optical axis on the predetermined imaging plane FP, CCD line sensors Po _1, Po ₂
When the aperture of the taking lens is small with respect to the distance from the optical axis of the
This means that the light beam for off-axis distance measurement that enters the line sensors Po ₁ and Po ₂ passes through the opening of the photographing lens TL.

In the present invention, as described later, as information specific to various lenses, which of the above-described CCD line sensors Po, Po ₁ and Po ₂ can be used without vignetting or not can be used as an AF enable / disable signal as an AF enable / disable signal in each lens. It is stored in ROM.

FIG. 5 shows the aperture openings (A ₁ , A ₂ , A ₃ , A ₄ , A _{5) of the} aperture mask AM for predetermined pupil planes of various types of interchangeable lenses.
And A ₆ ) and back-projected images A ₁₂ , A ₂₂ , A ₃₂ , A ₄₂ , A ₅₂ and A ₆₂ of the condenser lenses Lo, Lo ₁ and Lo ₂ are shown.

FIG. 5A shows a case of a lens having a large aperture.
Since the aperture is large, all back-projected images can pass through the aperture for detecting the focus of the photographing lens TL, and all the light beams for distance measurement that enter the CCD line sensors Po, Po ₁ , and Po ₂ are captured by the photographing lens TL. It can be used without vignetting on the eyes.
That is, all the focus detection areas Fa shown in FIG. 4, Fa _1, Fa ₂
To perform focus detection (see Table 1).

FIG. 5B shows the case of a lens having a small aperture.
For example, an interchangeable lens equipped with a teleconverter corresponds to this case. Since the aperture is small, the light beam that can enter the CCD line sensor without being vignetted by the pupil of the photographing lens TL is only the light beam for distance measurement on the optical axis. This is only the focus detection area Fa in the figure.

FIG. 5C shows the case of a lens whose opening position changes like a shift lens (shift lens here). When the shift amount is 0, the focus detection area effective for focus detection is only Fa, but the shift amount is X ₁ , X ₂ (0 <X ₁ <X
₂ ), the effective focus detection area also changes (see Table 1).

FIG. 5 (d) shows the case of a lens having an irregular opening such as a reflective telephoto lens. The shaded area is where the luminous flux is vignetted due to the reflecting mirror (secondary mirror), and the luminous flux for distance measurement on the optical axis is CCD
Focus detection area because it cannot enter the line sensor Po
It is impossible to perform focus detection with Fa.

On the other hand, the reflective telephoto lens shown in FIG. 5E has a small portion where the light beam is vignetted by the reflecting mirror, so that the light beam for distance measurement on the optical axis can enter the CCD line sensor Po.

As described above, which focus detection area is valid at the time of focus detection differs depending on the type of the interchangeable lens, and is stored in the ROM in the lens as lens-specific information (AF enable / disable signal) (see Table 1). 1).

Table 1 kind of differences due to available focus detection area of the lens _{(Fa, Fa 1, Fa 2} ) and the CCD line sensor (Po, Po _1, Po
₂ ) and an AF enable / disable signal. Focus detection area indicated by “○” in the table and CC arranged corresponding to it
The D line sensor can be used for focus detection. Also A
The F enable / disable signal is 8-bit data.

Fig. 6 shows the image plane best position and the CCD line sensor (hereinafter A
3 shows the relationship with the stop position of the photographing lens under visible light and infrared light under an F sensor. The horizontal axis X is an axis along the optical axis, the left side is the direction of the photographing lens (+ direction), the right side is the direction of the film surface (− direction), and the vertical axis Y
Represents the distance from the optical axis in a plane perpendicular to the optical axis. In the figure, the position indicated as on-axis is the position where the image forming performance of the image formed by the on-axis light (incident light parallel to the optical axis) is the best, but the film surface in the camera is at this position. In this case, the aberration performance with respect to off-axis light (incident light inclined with respect to the optical axis) deteriorates, and a good defocus amount cannot be obtained by focus detection using a light beam for off-axis distance measurement. Therefore, in consideration of on-axis light and off-axis light, the film surface is located at a position slightly shifted from the on-axis position (image plane best position). The aberration curve shown as an image is based on this image plane best position,
The magnitude of the deviation due to the actual transmitted light of the photographing lens (open aperture, for example, F = 2.0) indicates the position where the image contrast is the best.

On the other hand, the AF sensor, as described above,
Alternatively, focus detection is performed using only the beam for off-axis distance measurement, resulting in an effect equivalent to increasing the aperture value of the photographing lens, and the aberration performance on the AF sensor is the aberration of the entire photographing lens. Better than performance. The focus determination position by the AF sensor is shown as an AF sensor stop position under visible light or infrared light. Focus detection under infrared light means that if focus detection with visible light is impossible, infrared light is projected from the auxiliary light circuit built in the camera body,
This is the result of focus detection under infrared light projection. This auxiliary light circuit may be provided in a device outside the camera, for example, an electronic flash device.

As described above, there is a shift between the AF sensor stop position and the image plane best position, and the shift amount changes depending on the distance from the optical axis (image height). Therefore, in the present invention, the deviation amounts ΔSBon, ΔSBoff, Δsboff, ΔIRon, ΔIRoff, and Δiroff shown in the drawing are stored in the ROM in the lens, and the correction to the image plane best position is performed. The suffix ON is a correction amount for the focus detection area Fa for performing focus detection using the on-optical-axis distance measuring light beam, and the suffix OFF is a focus detection area Fa for performing focus detection using the off-optical-axis distance measuring light beam. It represents a correction amount related to _1, Fa _2. Area F
Since a ₁ and Fa ₂ look at positions that are symmetrical with respect to the optical axis, correction can be performed using the same correction data.

ΔSB is a deviation amount of the defocus amount between the AF sensor stop position and the image plane best position under visible light, and Δsboff is
This is the difference between the stop position of the AF sensor on the optical axis and the position off the optical axis under visible light. ΔIR is the difference between the AF sensor stop position under infrared light and the AF sensor stop position on the axis under visible light, and Δiroff is the AF sensor stop on the optical axis under infrared light and off the optical axis The difference in position.

Since these shift amounts (ΔSB, ΔIR) change due to zooming or focusing of the photographing lens,
The shift amount according to zooming or focusing is stored in the ROM in the lens as a correction amount. But,
Difference between the AF sensor stop positions on the optical axis and off-axis (Δsoff, Δiro
Since ff) hardly changes by zooming or focusing, this difference may be stored as a fixed value in the ROM in the lens.

Here, ΔSBon, ΔSBoff, ΔIRon,
ΔIRoff is a positive correction amount, and Δsboff and Δiroff are negative correction amounts.

When the amount of correction (ΔSB, ΔIR) is made variable by focusing, a distance encoder is provided in the lens similarly to the zoom encoder (61) in FIG. 1, and the output of this encoder and the output of the decoder (62) are provided. What is necessary is just to specify the address of ROM.

Hereinafter, the operation of the control CPU (100) in the camera body will be described with reference to the flowcharts of FIGS. 7 to 18.

FIG. 7 is a flowchart showing a main routine of an operation program of the control CPU (100). When the switch SW1, which is closed by pressing the release button in the first stage, is closed, the program is started from step # 700 (steps are omitted below), and various flags as shown in Table 2 are set in # 702. Reset to zero.

Table 2 describes various flags used in the control CPU (100). The details of the various flags will be described later.

In step # 704, since the ROM data is read for the first time since the control CPU is started, the read flag (F1) is set to 1, and the process proceeds to the lens data reading subroutine of step # 706. As will be described later, in the lens data reading subroutine, reading of ROM data, identification of lens attachment / non-attachment, identification of lens generation, and the like are performed, and the process returns to the main routine.

Next, the process proceeds to an automatic focus detection subroutine (hereinafter referred to as an AF subroutine) of # 708. In this AF subroutine, as described later, the focus of the subject is detected, and the lens is driven to bring the camera into a focused state.

In # 710, the film sensitivity data of the film cartridge inserted in the camera is read from the film sensitivity information circuit (360) into the control CPU, and in # 712, the photometric circuit (3
According to 10), photometry of the field luminance and A / D conversion are performed to obtain luminance value data. A known exposure calculation is performed based on the above data (# 714), and the obtained exposure-related value is displayed on a display circuit (340).
And display it (# 716).

Next, in step # 718, it is determined whether or not the switch SW1 is still turned on. If the switch SW1 is turned off, the process proceeds to step # 726, all the display circuits (340) are turned off and read. Control by resetting the flag (F1) to 0
U goes to sleep.

When the switch SW1 is determined to be on in # 718, it is determined in # 720 whether or not the switch SW2, which is closed by pressing the release button in the second stage, is on. If the switch SW2 is on, # 722 is determined. Performs a known release operation.
After the release operation is completed, the flow waits for the switch SW1 to be turned off at # 724, and proceeds to # 726. If the switch SW2 is off at # 720, the process returns to # 706 and repeats the operation from reading the lens data again.

FIG. 8 is a flowchart showing the lens data reading subroutine of FIG. 7 # 706. First, # 802
The read flag (F1) is 1 or 0, that is, the control CP
U Determine whether it is the first read of ROM data or the second or subsequent read after startup, and if it is the first read, # 804
If it is the second time or later, go to # 822.

Before describing the reading operation, lens information stored in the ROM in the lens will be described with reference to FIG.
The lens-specific information necessary for exposure control, AF control, etc., is stored in the interchangeable lens as 8-bit digital data.
Although the information is stored for each predetermined address in the ROM, when the camera is new and the functions are increased, the camera controls the new functions only with the information (conventional data) stored in the conventional lens (hereinafter referred to as the conventional lens). I can't do it. In this regard, a new lens (hereinafter referred to as a new lens) may be provided with a ROM that stores information (new data) corresponding to a new function in addition to the conventional information. FIG. 19 is a comparison diagram of the ROM area map between the conventional lens and the new lens.

Conventional lenses have lens information d ₁ to
di (conventional data) is stored, and lens information dn (lens type identification data) is stored at the last address n. Addresses i + 1 to n-1 are empty addresses in which no lens information is stored. ROM mounted on the new lens using what capacity is identical to the ROM of the conventional lens, until the address 1~i conventional data d ₁ -DI have been stored as it. In addition, newly added lens information di + _{1 to} dj (new data) are newly stored at addresses i + 1 to j, which were empty addresses, and lens type identification data dn is stored at the last address n as in the conventional lens. It is remembered.

In the present invention, a lens defined as a conventional lens includes a deviation amount between an image plane best position and an AF sensor stop position only in a focus detection area Fa where focus detection is performed using a light beam for distance measurement on the optical axis. ΔSBon, ΔIRon) are stored in the ROM in the lens as correction amounts (see Table 3). On the other hand, the new lens has a shift amount (ΔIRoff, ΔSBoff or Δiroff, Δsbof) due to aberration with respect to the focus detection areas Fa ₁ and Fa ₂ .
f) is newly stored.

Returning to FIG. 8, the read flag (F1) is set to 1 at # 802.
, That is, the first ROM data reading operation after the control CPU is started will be described. Since it is the first load,
First, in step # 804, the number n of all addresses of the ROM is set in the serial data counter (N) as the number of data to be read, and in step # 806, the current lens state by zooming or focusing is indicated in accordance with the in-body reading subroutine described later. Read n bytes of ROM data into the RAM stored in the n bodies. This completes the first reading, so the reading flag (F1) is reset to 0
(# 808).

Data called ICP is stored at the head address of the ROM. The first two bits of the eight bits are used to identify whether the lens is a conventional lens or a new lens. It consists of lens generation identification bit data indicating whether the lens is a lens. In # 810, the first two bits of the ICP data are used to determine whether a lens is attached to the body or not, and if no lens is attached, the process proceeds to # 836. Then, the lens flag (F3) is reset to 0 indicating that the lens is not attached, and the AF flag (AFF) is set to 1 indicating that the AF operation is not performed (# 838), and the routine returns.

If it is determined in step # 810 that the lens is mounted, first, in step # 812, the lens flag (F
3) is set to 1, and the process proceeds to the step of # 814 lens generation identification. In step # 814, it is determined whether the attached lens is a conventional lens or a new lens by using the remaining 6-bit data of the ICP. If it is determined that the lens is a new lens, all necessary lens information is stored in the RAM in the body, so that the lens generation flag (F2) is reset to 0 in # 816 and the routine returns. When the lens generation flag (F2) is set to 1, it indicates that the conventional lens is mounted, and when it is 0, the new lens is mounted.

If it is determined in step # 814 that the attached lens is a conventional lens, the lens generation flag (F2) is set, and new data not stored in the conventional lens is stored in the body data table according to the in-body data table reference subroutine described later. From the RAM stored in the body (# 82
0), return.

If the read flag (F1) is determined to be 0 in # 802, the control CPU has already performed one or more read operations of the ROM data. Judge if it is a new lens (# 82
2). In the case of a new lens, the number j of ROM data is set in the serial data counter (N) as the number of read data (# 824), and in the case of a conventional lens, the number i of ROM data is set in the serial data counter (N) ( # 826), # 806
Execute the in-body read subroutine in the same way as
828). However, as described above, j> i, and the reading time of the ROM data is reduced by designating the number of data.

# 830 is a lens mounting identification step based on the read ICP data, similarly to # 810. If a lens is mounted, the process proceeds to # 832, and the lens flag (F3) is identified to determine the last time. At the time of reading the lens data, it is determined whether the lens is attached or not. The fact that the lens flag (F3) is 0 means that the lens has not been attached last time and the lens has been newly attached this time. Therefore, the lens flag (F3) is set to 1 indicating the lens attached state, and the process proceeds to # 804. Migrate and ROM again
Read n data.

FIG. 9 shows a subroutine for reading data into the RAM in the body shown in FIGS. # 806 and # 828, and shows an operation of reading ROM data into the RAM in the camera body. First sets ROM data storage start address m ₀ in the RAM address pointer (M) at # 902. The RAM has an 8-bit configuration like the ROM. Next, in # 094, the serial flag (F4) is reset to 0 to indicate that the reading of the serial data from the ROM is not completed, and the serial counter (120) in FIG. 2 counts the clock pulse for 8 bits. Is set to 8 (# 906).

When the output terminal CS shown in FIG.
Serial communication between the body and the lens becomes possible. # 91
0 sets the serial port control register (SCKC) to 1
Is set, the clock pulse starts to be output from the clock output terminal Sck shown in FIG. Step # 912 is a step of waiting for the completion of the processing of the serial interrupt. The step of waiting for the serial interrupt to be performed and setting the serial flag (F4) to 1, that is, reading the one-byte serial data of the ROM into the RAM. It is in a waiting state.

The serial interrupt processing operation will be described with reference to FIG. When the serial counter (120) finishes counting eight clock pulses, it generates an interrupt signal (INT) to the control CPU. That is, while the control CPU is waiting for the serial flag (F4) to become 1 in # 912 in FIG. 9, the serial counter (120) finishes counting eight clock pulses and outputs an interrupt signal (INT). ), And the flow chart shifts to FIG. First, in # 1002, the serial port control register (SCKC) is reset to 0 in order to stop the output of the clock pulse from the body side to the lens side. Next, in # 1004, the data of the predetermined ROM address of 8 bits read into the serial register (121) is transferred to the address (initially m ₀ ) designated by the address pointer (M) in the RAM. Store. At # 1006, the address pointer (M) for designating the storage destination RAM address is advanced by one, and at # 1008, the reading of one byte of serial data of the ROM into the RAM is completed. Set the serial flag (F4) to 1 and set the next ROM
8 in the serial counter (120) for reading data
Is set (# 1010), and the process returns to # 912 in FIG.

In # 912, it is determined that the serial flag (F4) is set to 1, so the flow proceeds to # 914. In # 914, 1 is subtracted from the serial data counter (N), and the serial flag (F4) is set. It is reset to 0 again (# 915).

The determination flow of # 916 determines whether all the ROM data corresponding to the number set in the serial data counter (N) has been stored in the RAM in the body, and if all the data has been read, N = 0. Therefore, at # 918, the output terminal CS is set to high to end the communication between the body and the lens, and the routine returns. If reading of all data has not been completed, the process returns to step # 910 to read the next ROM data.

FIG. 11 is a subroutine for referencing the in-body data table shown in FIG. 8 # 820. When a conventional lens is mounted, lens information (new data) not stored in the conventional lens is referred to the body data table. Then in the body
The operation of storing data in the RAM will be described.

FIG. 20 is an area map of the in-body data table. At the last n addresses of the ROM in the lens, lens type identification data (dn) is stored without distinction between the conventional lens and the new lens. Lez type identification data (dn) has the value of dn ₁ to dne depending on the type of lens. The data (di + 1 to dj) corresponding to the new data newly stored in the new lens according to the lens type of the conventional lens is stored in the in-body data table.

Returning to FIG. 11, first, in # 1102, the control CPU receives lens type identification data (dn) from the RAM. Received dn =
Based on dnk (1 ≦ k ≦ l), the in-body data table area number k is set in the counter (K) (# 1104), and the reference data number j from the in-body data table is set in the serial data counter (N). -Set i (# 1106),
Also, the lens ROM data storage start address m ₀ + i is set in the RAM address pointer (M) (# 1108). RAM m
₀ The ~m ₀ + i-1 address, are stored in a conventional data already stored in the ROM.

In # 1110, the data corresponding to the lens type identification data (dnk) is referenced by one byte from the data table in the body and stored in the RAM address specified by the address pointer (M). Thereafter, as in the case of the lens data reading subroutine, the data from the data table in the body to dj is referenced byte by byte and stored in the RAM.

Table 3 shows what kind of lens information is stored in the RAM stored in the body only for data used in the embodiment, and addresses are given for convenience. As already described in detail, in view of the correspondence with the lens side, the ROM of the conventional lens has at least 1 to 5 in the RAM.
And the lens information of the address n, and the lens information of the addresses 1 to 5, i + 1 to i + 4, and n in the RAM are stored in the ROM of the new lens. In the conventional lens, lens information corresponding to the contents of i + 1 to i + 4 is read from the data table in the body according to the lens type, and the lens information in the body is read out.
Stored in RAM. The indication (variable) indicates that the data is variable data that changes by zooming or focusing. The conversion coefficient K is obtained by dividing the lens drive amount by the defocus amount, and is used to calculate a lens drive amount necessary for focusing from a lens control defocus amount obtained by a focus detection operation described later. When the lens is not a shift lens, the shift amount of the shift lens is fixed to zero.

FIG. 12 is a flowchart showing the AF subroutine of FIG. 7 # 708.

In # 1202, the state of the AF flag (AFF) is determined. A
The F flag (AFF) is a flag which is set to 1 when the lens is not mounted in # 810 or # 830 in FIG. 8, or is set after the lens is in focus as described later. In other words, if the AF flag (AFF) is set to 1, either the camera is in focus or no lens is attached, and the flow returns without performing the focus detection operation (# 1246). If the AF flag (AFF) is 0, the state of the auxiliary light flag (F5) is determined in # 1204. If the auxiliary light flag (F5) is set to 1, the focus detection operation using the auxiliary light (F5) is performed. The process proceeds to # 1218 to # 1232).

If auxiliary light flag (F5) is 0 in # 1204, the AF sensor (CCD line sensor) Po, is integral with Po _1, Po ₂ is carried out in a known manner, integrated data is dumped in # 1206 (#
1208).

# 1210 is a subroutine of a focus detection calculation using the above-described integral data, which will be described with reference to FIG. # 1302 is a focus detection calculation for each focus detection region Fa, in each Fa _1, Fa _2.
Each AF sensor Po, Po ₁ , Po ₂ has a reference part and a reference part, respectively.
Two light receiving element rows are formed, and in the focus detection calculation,
By using the signals of these light receiving element rows, calculations such as a contrast calculation and a correlation calculation of the subject are performed, and data relating to the defocus amount which is data necessary for focus detection, data indicating reliability of focus detection, and the like are created. Things. still,
For more detailed control, the present applicant has disclosed in
What is necessary is just to use the method filed in US Pat. The result obtained by this focus detection calculation is used for determining whether or not focus detection can be performed in each focus detection area and calculating the defocus amount, as described later.

In # 1304, various low contrast flags (LCF, LCF1, LCF2, LC
Reset F3). The low contrast flag is a flag indicating whether focus detection is possible or impossible based on the result of the focus detection calculation. If the flag is 1, the focus detection is impossible, and if the value is 0, the focus detection is possible. On the other hand, the above-mentioned AF enable / disable signal stored in the ROM in the lens is a signal for specifying an available focus detection area depending on the shape of the lens regardless of the result of the focus detection calculation.

In # 1306, based on the result of focus detection calculation for AF sensor Po ₁ that are arranged corresponding to the focus detection area Fa _1, allows focus detection in the focus detection area Fa _1, it is determined not, focus detection as if possible, Rokonfuragu for the area Fa ₁ in # 1308 if not the focus detection (L
CF1) is set to 1 and the flow shifts to # 1310. # 1310 to 1
316, similarly focus detection area Fa, the focus detectable in Fa _2, it is impossible for determination flow.

Next, in step # 1318, an AF enable / disable signal among lens information stored in the RAM in the body is received, and the data is stored as (00
H) to # 1320 (01H) to # 1330, (02H) to # 1
The process moves to # 336, to # 1344 if (03H), or to # 1350 if (04H) (see Table 1). In each flow,
In the focus detection area specified by the AF enable / disable signal, it is determined whether focus detection was possible or impossible by referring to the low contrast flag for that area. If the focus cannot be detected, the low contrast flag (LCF) is set to 1 and the routine returns. On the other hand, if there is at least one focus detectable area, the process directly returns. For example, if (02H) is received as the AF availability signal,
The process moves from # 1318 to # 1336. AF availability signal (02H)
Since designated Fa and Fa ₂ as a focus detection area, it is determined Rokonfuragu and (LCF2) possible not focus detection by the focus detection calculation based on (LCF3). If it is determined in step # 1338 that the low contrast flag (LCF2) is 0, it means that the focus can be detected in at least the focus detection area Fa, and the process returns. Even if the low contrast flag (LCF2) is 1 in # 1338, the low contrast flag (LC
F3) if is 0, the process returns so that can focus detection at least the focus detection area Fa _2. If both low contrast flags are 1, it means that the focus can be detected over the entire area. Therefore, the low contrast flag (LCF) in # 1342 is set to 1 before returning. The same applies when another AF availability signal is received.

Returning to FIG. 12, # 1212 is a flow for determining whether or not focus detection is possible over the entire area based on the low contrast flag (LCF) determined in the above-described focus detection calculation subroutine.
If the low contrast flag (LCF) is 1, it means that focus detection cannot be performed in all areas, so the focus detection operation using the auxiliary light after # 1218 after setting the auxiliary light flag (F5) to 1 in # 1216. Move to. In many cases, the focus detection is determined to be impossible by the focus detection calculation because the contrast of the subject is extremely low or the brightness of the subject is extremely low. The built-in auxiliary light is emitted to integrate the light received by the AF sensor. The focus detection calculations of # 1226 and # 1228 and the focus detection enable / disable judgment by the low contrast flag (LCF) are the same as in # 1210 and # 1212 described above. If focus detection is not possible even with light-receiving integration that emitted auxiliary light, a warning is displayed on the display circuit (340) in step # 1232 indicating that focus detection is not possible, and the AF flag (AFF) is set to 1. And return (# 1240, # 1246).

The defocus amount calculation subroutine of # 1214 or # 1230 will be described with reference to FIG. 14 to FIG.

FIG. 14 shows an embodiment of a subroutine for calculating the defocus amount (A) under visible light of # 1214. # 1402 through #
1406 indicates the defocus amount calculation in the focus detection area Fa _1. # Determines the state of Rokonfuragu (LCF1) corresponding to the focus detection area Fa ₁ in 1402, the flag (LCF1) focus detection in 1 if region Fa _1, i.e. to # 1408 so calculated impossible defocus amount Transition. In step # 1404, the defocus amount (Δξ1) is calculated based on the result of the focus detection calculation. As described with reference to FIG. 6, there is a certain gap between the image plane best position, which is the actual film surface, and the AF sensor stop position by the focus detection by the AF sensor.
Therefore, the defocus amount (Δξ1) obtained as a result of the focus detection calculation based on the output of the AF sensor cannot accurately indicate the image plane best position. Therefore, in step # 1406, a correction operation for focusing on the image plane best position is performed. That is, the correction is performed by the following calculation Δξ1 ′ = Δξ1 + ΔSBon + Δsboff (1). Here, ΔSBon is conventional data, data variable by zooming or focusing, and Δsboff is new data and fixed data that does not change by zooming or focusing.

Similarly, # 1408 to # 1412 are the calculation flow of the defocus amount in the focus detection area Fa, and the defocus amount (Δξ2) obtained based on the result of the focus detection calculation is corrected by the following calculation. .

Δξ2 ′ = Δξ2 + ΔSBon (2) That is, since the focus detection area Fa is focus detection using a light beam for distance measurement on the optical axis, correction is performed using only the conventional data ΔSBon. Of course, ΔSBon is variable data.

# 1414 to # 1418 is a calculation flow of the defocus amount in the focus detection areas Fa _2, as the correction calculation is the same as equation (1), as follows.

Δξ3 ′ = Δξ3 + ΔSBon + Δsboff (3) The characteristic of the defocus amount calculation (A) subroutine under visible light is that the variable data ΔSBon on the axis stored as conventional data in the ROM of the conventional lens is used.
This is the point that off-axis variable data is newly created, and the only data (new data) to be newly stored for this purpose is fixed data Δsboff. Also, the focus detection areas Fa ₁ and Fa ₂
Performs focus detection based on a light beam that has passed through a region that is substantially symmetrical with respect to the optical axis of the lens. Therefore, only one correction amount (Δsboff) used for the correction operation needs to be stored.

FIG. 15 shows an embodiment of a defocus amount calculation (A) subroutine using the auxiliary light of # 1230. As in the defocus amount correction calculation under visible light in FIG. New variable data is created using the variable data of the conventional data. The flow of the flowchart is 14th
Since it is completely the same as the case of the figure, only the correction calculation will be described.

When projecting infrared light as an auxiliary light onto a subject and receiving infrared light reflected from the subject to perform focus detection, the amount of defocus during focus detection under visible light due to lens chromatic aberration (See FIG. 6). The correction of the defocus amount (Δξ2) by the focus detection calculation obtained in the focus detection area Fa using the light beam for distance measurement on the optical axis is performed by the following equation.

Δξ2 ′ = Δξ2 + ΔSBon + (a × ΔIRon + b) (4) Here, ΔIRon is conventional data, which is variable by zooming or focusing. a
Is a correction coefficient indicating a ratio between the correction amount ΔIRon ′ of the auxiliary light used in the present embodiment at the used infrared wavelength and the correction amount ΔIRon when the infrared light having the wavelength of 800 nm is used. The correction amount ΔIRon stored as lens information together with the conventional lens and new lens is the correction amount at a wavelength of 800 nm, so if an auxiliary light with a wavelength other than 800 nm is projected, a correction that matches that wavelength is required Becomes Δ as the correction coefficient a
The reason for having the ratio of IRon 'to ΔIRon is that the chromatic aberration of the photographing lens changes linearly in the infrared wavelength range, and this ratio does not change much by zooming or focusing. b is the infrared light characteristic at the used infrared wavelength of the autofocus sensor module (dotted line in FIG. 3, block AF part) used in the present embodiment, that is, the ΔIR correction value of the autofocus sensor module. . The correction coefficients or correction values for a and b are stored in the E ² PROM
Is stored in

On the other hand, focus detection area using off-axis distance measuring light beam
The correction of the defocus amount (referred to as Δξ) obtained at Fa ₁ or Fa ₂ is based on the following equation.

Δξ ′ = Δξ + ΔSBon + (a × ΔIRon + b + Δiroff) (5) Δiroff is new data and is fixed data that does not change due to zooming or focusing. The data to be stored as new data may be only the fixed data Δiroff.

FIG. 16 is a defocus amount calculation (B) subroutine under visible light, which is another embodiment of FIG. For correction in the focus detection areas Fa ₁ and Fa ₂ , variable data ΔSBoff is previously stored as new data by zooming or focusing without using variable conventional data (ΔSBon). . That is, the correction of the defocus amount (referred to as Δξ) obtained in the focus detection area Fa ₁ or Fa ₂ is performed as follows.

Δξ ′ = Δξ + ΔSBoff (6) The focus detection area Fa is the same as the equation (2) using the on-axis correction data ΔSBon.

The capacity of the ROM for storing new data naturally increases by the amount of change due to zooming or focusing, but for lenses where the difference Δsbff between the on-axis and off-axis AF sensor stop positions greatly changes due to zooming or focusing. Is valid.

FIG. 17 shows the defocus amount calculation using the auxiliary light (B)
This is a subroutine, which is another embodiment of FIG. No. 16
As in the figure, variable data ΔIRoff is stored in the ROM in the lens as new data by zooming or focusing. Therefore, the correction of the defocus amount (referred to as Δξ) obtained in the focus detection area Fa ₁ or Fa ₂ is performed as follows.

Δξ ′ = Δξ + ΔSBon + (a × ΔIRoff + b) (7) For the focus detection area Fa, the on-axis correction data ΔSBon,
This is the same as Expression (4) using ΔIRon.

Returning to FIG. 12, # 1234 is the above # 1214 or # 12
This is a lens control defocus amount calculation subroutine for calculating a lens control defocus amount necessary for driving a lens from the defocus amounts of a plurality of focus detection areas obtained in 30. In # 1236, it is determined whether or not the current lens position is in focus based on the calculated control defocus amount, and if in focus, the display circuit (34) is determined in # 1238.
At 0), a display indicating the in-focus state is performed, and the flow shifts to # 1240.
If the lens is not in focus, the necessary lens drive amount is calculated from the control defocus amount obtained by the control defocus amount calculation and the conversion coefficient K stored in the ROM (# 124).
2) Then, the lens is driven (# 1244), and the flow shifts to the in-focus display flow of # 1238.

FIG. 18 shows the control defocus amount calculation subroutine of FIG. 12 # 1234 in detail. First, in # 1802, an AF enable / disable signal is received from lens information stored in the RAM in the body, and the flow shifts to each flow according to the data. For example, if the AF enable / disable signal is (00H), Δξ = f (Δξ1 ′, Δξ2 ′, Δξ) of # 1806
The lens control defocus amount is calculated by 3 '). The function f is a defocus amount Δ of a plurality of focus detection areas.
Only the effective defocus amount is selected from ξ1 ′, Δξ2 ′, and Δξ3 ′, and the lens control defocus amount is calculated in accordance with a predetermined evaluation algorithm. If the AF enable / disable signal is (01H), the defocus amount detected in the focus detection area Fa in # 1810 is directly used as the defocus amount for lens control. When the AF availability signal is (02H), (03H), or (04H), the defocus amount for lens control is calculated according to each flow. The details are described in, for example, JP-A-61-55618 filed by the present applicant.

(Effect of the Invention) As described above in detail, in focus detection for a subject in an area outside the optical axis, the correction amount stored in the first correction amount storage unit and the second, third, and fourth correction amount storages The defocus amount is corrected based on one or more correction amounts from the correction amounts stored in the means. Therefore, the focus can be detected with high accuracy even for a subject located outside the optical axis.

By storing a correction amount as a correction amount for performing correction corresponding to a certain wavelength, for example, a wavelength of light emitted from the auxiliary light means, the correction of the defocus amount can be performed even in focus detection using the auxiliary light. This allows accurate focus detection.

[Brief description of the drawings]

FIG. 1 is a block diagram showing an overall circuit configuration of an embodiment of the present invention, FIG. 2 is a diagram showing a configuration of an input / output terminal of a control CPU,
FIG. 3 is a schematic view of an optical device for focus detection in one embodiment of the present invention, FIG. 4 is an inside view of a viewfinder showing a focus detection area of a field, and FIG. FIG. 6 is a back-projection view of the aperture mask, FIG. 6 is a view showing the relationship between the focus position by the AF sensor and the best image plane position based on the aberration of the photographing lens, FIG. 7 is a flowchart showing the main operation of the control CPU, FIG. 9 is a flowchart showing a ROM data reading subroutine, FIG. 9 is a flowchart showing a reading subroutine to the RAM in the body, and FIG. 10 is a control CP.
A flowchart showing a serial interrupt processing routine to U, FIG. 11 is a flowchart showing a data table reference subroutine in the body, FIG. 12 is a flowchart showing an automatic focus detection subroutine, FIG. 13 is a flowchart showing a focus detection calculation subroutine, and FIG. FIG. 14 is a flowchart showing one embodiment of a defocus amount calculation subroutine under visible light, FIG. 15 is a flowchart showing one embodiment of a defocus amount calculation subroutine using auxiliary light,
FIG. 16 is a flowchart showing another embodiment of a subroutine for calculating a defocus amount under visible light, FIG. 17 is a flowchart showing another embodiment of a subroutine for calculating a defocus amount using auxiliary light, and FIG. 18 is a lens. 19 is a flowchart showing a control defocus amount calculation subroutine, a nineteenth embodiment;
The figure shows an area map of the ROM in the lens, and FIG. 20 shows the area map of the data table in the body.

Claims (6)

(57) [Claims] In a focus detection system for an interchangeable lens camera, a light beam from a subject located in a region outside the optical axis of the interchangeable lens is split into a pair of light beams passing through different regions of an exit pupil plane of the interchangeable lens. Optical means for forming a pair of light images from a light beam; light receiving means for receiving the pair of light images; focus detection for calculating a defocus amount of the interchangeable lens by detecting a focus on a subject based on an output of the light receiving means Means, a first correction amount storing means for storing a correction amount for correcting a defocus amount when performing focus detection on a subject on the optical axis in order to perform the first correction, and A second correction amount storing means for storing a correction amount for correcting a defocus amount when performing focus detection on a subject located in a region outside the optical axis; To make corrections A third correction amount storing means for storing a correction amount for correcting a defocus amount when focus detection is performed on a subject on the optical axis; and a second correction different from the first correction. A fourth correction amount storage unit that stores a correction amount when focus detection is performed on a subject located outside the optical axis; and a first correction amount storage unit that stores the correction amount when focus detection is performed outside the optical axis. Determining means for determining which correction amount among the correction amounts of the second to fourth correction amount storage means is to be used, in addition to the correction amount; A focus detection system for an interchangeable lens camera, comprising: a correction unit that corrects a focus amount; and a lens driving unit that drives an interchangeable lens according to the corrected defocus amount obtained by the correction unit. 2. The apparatus according to claim 1, wherein said third and fourth correction amount storage means store a correction amount for correcting a defocus amount of light having a certain wavelength corresponding to a predetermined area of the photographing screen. The focus detection system for an interchangeable lens camera according to claim 1. 3. The lens according to claim 2, wherein said correction amount stores a value corresponding to light of a predetermined wavelength of auxiliary light means for projecting light toward a subject for focus detection. Focus detection system for interchangeable cameras. 4. A defocus amount of the interchangeable lens is calculated based on a pair of light beams from a subject in a region outside the optical axis of the interchangeable lens that has passed through different regions of the exit pupil plane of the interchangeable lens,
In the interchangeable lens used for the focus detection system of the interchangeable lens camera which corrects the defocus amount and drives the interchangeable lens according to the corrected defocus amount, the first correction is performed on the optical axis. First correction amount storage means for storing a correction amount for correcting a defocus amount when focus detection is performed on a certain subject; and focus detection of a subject located outside an optical axis for performing the first correction. A second correction amount storage unit storing a correction amount for correcting the defocus amount in the case; and performing focus detection on a subject on the optical axis to perform a second correction different from the first correction. A third correction amount storing means for storing a correction amount for correcting the defocus amount in the case; and performing a second correction different from the first correction to focus an object in an area outside the optical axis. Stores the correction amount when detecting And a fourth correction amount storage means. 5. The apparatus according to claim 1, wherein said third and fourth correction amount storage means stores a correction amount for correcting a defocus amount of light having a certain wavelength corresponding to a predetermined area of the photographing screen. The interchangeable lens according to claim 5, wherein 6. The exchange according to claim 6, wherein the correction amount stores a value corresponding to light of a predetermined wavelength of auxiliary light means for projecting light toward a subject for focus detection. lens.