JPS63286830A - Lens exchangeable focus detecting system and interchangeable lens - Google Patents

Abstract

PURPOSE:To accurately discriminate the propriety of the detection of focus based on data concerning a projecting pupil read from a lens, by discriminating whether a focus detection means can execute the optically accurate detection of focus based on the data concerning the projecting pupil from the interchangeable lens and actuating the focus detection means if the detection of focus can be possible. CONSTITUTION:The data peculiar to the lens is fixedly stored in a storage means 6. When a reading signal from a body is inputted by a reading signal input means 7, a data transmission means 8 sequentially transmits the data stored in the storage means 6 to the body based on the reading signal. Since the data concerning the diameter of the projecting pupil and the position of the projecting pupil of the lens and the correction of image height is included in the data stored in the storage means 6, the shape of the projecting pupil can be corrected on the body side based on each data and the data concerning the projecting pupil can be accurately transmitted to the body even in the case of combining with the body having a distance measuring area outside an optical axis. Thus, whether the accurate detection of focus can be possible is accurately discriminated.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to an interchangeable lens focus detection system and an interchangeable lens using a TTL phase difference detection method.

(Prior Art) Conventionally, subject light that has passed through first and second portions of the exit pupil plane of an interchangeable lens is formed as first and second light images,
A TTL phase difference detection type focus detection device that determines the focus detection state based on the image interval is widely used in automatic focus adjustment devices of -eye reflex cameras. In this type of focus detection device, the position and size of the AP pupil through which the AP light flux used for focus detection is determined by the design of the camera body. For example, there will be no currant in the AP light flux, and this will not interfere with the focus detection operation. However, the position and size of the exit pupil of the interchangeable lens are not constant, and the AF pupil may deviate from the exit pupil, causing the AP Claret may appear in the luminous flux. In this case, there is a problem that a focus detection error occurs or the focus cannot be detected.

Therefore, it has conventionally been proposed to provide multiple types of groups of a pair of photosensors for focus detection, and to select and use one type of photosensor group depending on the maximum aperture value of the lens being used (
However, this conventional technology does not accurately compare the size or positional relationship between the exit pupil of the interchangeable lens and the AF pupil of the camera body. It was not possible to accurately determine the presence or absence of Kuraray. Further, in particular, no consideration is given to the case where the shape of the exit pupil as seen from outside the optical axis changes.

On the other hand, as an interchangeable lens group for single-lens reflex cameras equipped with TTL AE and AF functions, AE-related data such as open aperture value, maximum aperture value, and focal length, as well as AF-related data such as lens extension amount conversion coefficients, etc. , many lenses have been developed that have a fixed memory that can be read by the camera body. However, since the exit pupil data is often estimated from the open aperture value data, a lens in which this data is fixedly stored together with the open aperture value has not been proposed.

(Problems to be Solved by the Invention) As mentioned above, in the method disclosed in Japanese Patent Publication No. 62-6206, it is determined whether or not focus detection is possible according to the open aperture value of the interchangeable lens. However, with the development of camera systems, there are cases where it is not possible to correctly determine whether or not focus can be detected using only the maximum aperture value of an interchangeable lens.For example, when determining the composition of a photograph, if the main subject is at the edge of the screen Although it would be convenient to have a distance measurement area off the optical axis, compared to the case where focus detection is performed in the distance measurement area on the optical axis, the focus detection optical system is designed to detect the exit pupil of the interchangeable lens from an oblique direction. As a result, the shape of the exit pupil changes, and there is a problem in that it is no longer possible to accurately determine whether or not focus detection is possible using data on the open aperture value alone.

The present invention has been made in view of the above, and its purpose is to provide a lens-interchangeable focus detection system that can correctly determine whether or not focus detection is possible based on exit pupil data read from the lens. We provide systems and interchangeable lenses.

(Means for Solving the Problems) In order to achieve the above object, in the lens interchangeable focus detection system according to the present invention, as shown in FIG.
Optical means 1 that divides a light beam from a subject in an area not including the optical axis of the interchangeable lens 11 into a pair of light beams that pass through different areas of the exit pupil plane of the interchangeable lens 11, and forms a pair of optical images from the light beams. and a light receiving means 2 for receiving the pair of optical images. .

22, a focus detection means 3 that detects the focus of the interchangeable lens 11 by detecting the relative displacement of a pair of optical images based on the output of the light receiving means 21.2□, and an exit pupil from the interchangeable lens 11. Based on the data, a determining means 4 determines whether or not the focus detecting means 3 can perform optically accurate focus detection based on the combination of the optical means 1 and the optical system of the interchangeable lens 11; If there is an operation permitting means 5 for operating the focus detecting means 3.

However, FIG. 1 is an explanatory diagram showing the configuration of the present invention in functional blocks, and in the embodiments described later, a part of the focus detection means 3, the discrimination means 4, and the operation permission means 5 are implemented by a microcomputer. This is achieved through a program.

In addition, in order to achieve the above object, the interchangeable lens according to the merged invention includes a storage means 6 that fixedly stores data unique to the lens, and a storage means 6 that stores data unique to the lens, and It is equipped with read signal input means 7 for inputting a signal, and data sending means 8 for sequentially sending data stored in the storage means 6 to the body based on the read signal. is characterized in that it includes data regarding the exit pupil diameter of the lens, the exit pupil position, and image height correction.

(Operation) The operation of the present invention will be explained with reference to FIG. Regarding the lens interchangeable focus detection system shown on the right side of FIG. The light beam is divided into a pair of light beams passing through the light beam, and a pair of light images are formed from the light beams, and the light receiving means 2□, 22 receive the pair of light images. The focus detection means 3 is the light receiving means 21.2□
The determination means 4 detects the focus of the interchangeable lens 11 by detecting the relative displacement of a pair of optical images based on the output of the optical means 1 and 3, based on the data regarding the exit pupil from the interchangeable lens 11. Based on the combination of the interchangeable lens 11 and the optical system, it is determined whether the focus detection means 3 can perform optically accurate focus detection. The operation permission means 5 operates the focus detection means 3 if focus detection is possible. Therefore, in this lens interchangeable focus detection system, by reading data regarding the exit pupil from the interchangeable lens 11, it is possible to determine whether or not optically accurate focus detection is possible using only data on the open aperture value. This allows for more accurate results compared to

Next, regarding the interchangeable lens shown on the left side of FIG. 1, data specific to the lens is fixedly stored in the storage means 6. When a read signal from the body is input by the read signal input means 7, the data sending means 8 sequentially sends the data stored in the storage means 6 to the body based on this read signal.

The data stored in the storage means 6 includes data regarding the exit pupil diameter, exit pupil position, and image height correction of the lens. Even in such a case, the shape of the exit pupil can be corrected on the body side based on the above data, and the data regarding the exit pupil can be correctly transmitted to the body.

(Example) FIG. 2 is a diagram showing a schematic configuration of a multi-point ranging module installed in a single-lens reflex camera. In the figure, 11 is a photographing lens, 12 is a main mirror, 13 is a film surface, 14 is a sub-mirror, and 15 is a focus detection optical system. 22 is a field stop arranged near the focal plane, and has a rectangular opening 22a,
22b and 22c. 21a, 2 lb, 21
c is a condenser lens, 20 is a module mirror, ],
8m, 18b, 18c are separator lens pairs, 1
6m, 16b, 16c are focal planes 17 of separator lenses
This is an array of CCD image sensors arranged in . 19 is an aperture mask, which has circular or oval openings 19a, 19b, 19;
It has c. The image whose field of view is limited by the rectangular opening 22a passes through the condenser lens 21m, and is projected as two images onto the CCD image sensor array 16& by the field stop 19a and the separator lens pair 18a. This 2
When the image interval between the two images is a predetermined interval, it is determined that the image is in focus, when it is narrower than the predetermined interval, it is determined that the front focus is on, and when it is wider than the predetermined interval, it is determined that the rear focus is determined.

Similarly, the images of the field stops 19b and 19e are the condenser lenses 21b and 21c and the separator lens pair 18b.

18c onto the CCD image sensor arrays 16b and 16c.

FIG. 3 shows a focus detection optical system 15a (a combination of a condenser lens 21m, a separator lens pair 18a, and a CCD image sensor array 16m) located above the optical axis 2 in FIG. The optical system 15b (a combination of a condenser lens 21b, a separator lens pair 18b, and a CCD image sensor array 16b) is extracted.

The distance measurement frames A and B are the focus detection frames shown on the film isometric plane F. Hereinafter, A will be referred to as an on-axis ranging frame, and B will be referred to as an off-axis ranging frame. In addition, ranging frames A and B are projected onto the object surface via the photographing lens 11, and A' and B will be referred to as ranging frames A' and B. '. On the exit pupil plane of the photographic lens 11, a separator lens pair 18m in the focus detection optical system 15a located on the axis is connected to a condenser lens 21a.
Images projected by 11a and 11b are shown by 11a and 11b. Images 11c and 11d are images of the separator lens pair 18b in the off-axis focus detection optical system 15b projected by the condenser lens 21b.

Figure 4 shows the exit pupil aperture of the photographing lens at any exit pupil position of the photographic lens and the focus detection optical system.
FIG. 3 is a diagram generally showing the positional relationship of the passband of the F light beam. 5 and 6 are diagrams for explaining AF pupil-related constants, which are determined by the design and arrangement of the focus detection optical system, among the parameters shown in FIG. 4. FIG. 5 shows the focus detection optical system 15a on the optical axis viewed from the direction of the arrow (x) in FIG.
) A similar diagram is obtained when the focus detection optical system 15b outside the optical axis is viewed from the direction. FIG. 6 is a view of the off-axis focus detection optical system 15b viewed from the direction of arrow (x).

Before entering into the following description, various parameters and constants used in FIGS. 4 to 6 will be explained.

In FIG. 4, Pz is the exit pupil position, which means the distance between the film equivalent plane F and the exit pupil plane of the predetermined photographic lens.

Po is the outer exit pupil radius at the exit pupil position Pz, and is hereinafter referred to as the exit pupil outer diameter.

ΔPo is a parameter for correcting the shape of the outer exit pupil when viewed from a predetermined image height position, and is hereinafter referred to as outer exit pupil image height correction data (or "outer image height correction data" for short). ”).

Po' is when the photographic lens is a reflective telephoto type.
Exit pupil radius for regulating the inner exit pupil, hereinafter referred to as exit pupil inner diameter, exit pupil outer diameter P0 and exit pupil inner diameter P0
Generally, the positions of the exit pupils are not necessarily the same, but in the following explanation, they are assumed to be at the same position.

ΔP0' is a parameter for correcting the shape of the inner exit pupil when viewed from a predetermined image height position;
The shape of the exit pupil, which is called inner exit pupil image height correction data (or "inner image height correction data" for short), is usually circular, but as the image height on the film plane becomes higher, , the shape is close to an ellipse, as shown by the broken line in FIG. ΔP0 and ΔP0° are parameters for expressing the amount of change in shape.

AFP is an AF light flux region, which enters the focus detection optical system and indicates a pass range of the AF light flux.

Ho indicates the amount of deviation of the AP light flux area AFP from the principal optical axis 2 of the photographing lens. In the case of the focus detection optical system 15m located on the optical axis, Ho indicates the amount of deviation H (1=0).

ro indicates the size of the AP light flux area AFP at the exit pupil position Pz.

do represents the distance between the two AP light flux areas AFP at the exit pupil position Pz. This distance d0 is an amount that affects the detection sensitivity of the focus detection optical system, and the larger the distance d0, the greater the focus detection sensitivity. Although it will be more expensive, it will not be possible to use a photographic lens with a small exit pupil diameter.

Δd represents the amount of blur in the AF light flux area AFP in the focus detection optical system.

OUT is the outer pupil margin that the light flux entering the focus detection optical system has with respect to the photographing lens, and is expressed by the following formula %Equation %Especially, when the focus detection optical system is 15m on the axis, it is usually H
o=O1AP,=Q, and OUTZ=P e -re do-Δd/2.

IN is the inner pupil margin when the photographic lens is a reflective telephoto type, and is expressed by the following formula.

IN=(()I,+ΔP0°)”+(d,-Δd/2
)il+/2-r6-P6゜Especially in the case of the on-axis focus detection optical system 15a, H0=0
, ΔP0=0, and I Nz=d, −Δd/2 r. Po.

Depending on the sign of the outer and inner pupil margins OUT and IN, selection of a distance measurement frame and selection of a distance measurement area within the distance measurement frame, which will be described in detail later, are performed.

Next, in FIG. 5, a is the distance from the condenser lens 21a to the isoinclined plane F of the film.

t is from condenser lens 21m to separator lens 1
8a (or the aperture mask 19a that is closest to the aperture mask 19a).

Ps is a position where an image (hereinafter referred to as "AP@") of the separator lens 18a (or the aperture mask 19a immediately adjacent thereto) by the condenser lens 21a is projected, and hereinafter this is referred to as the AP pupil position. .

0s is a point on the optical axis at the AF pupil position gPs, and Qs
Qs' is AF pupil closed and apertured.

The AP pupil position Ps and the AFIIirM mouth QsQs' are uniquely determined by the power of the condenser lens 21m and the distances a and t described above. Therefore, from the point Os on the optical axis, the AP pupil aperture Q! The distances 0sQs' and 0sQs from the farthest point Qs and the nearest point c1g' of IQS' can be regarded as constants. Furthermore, the size e of the ranging frame on the film isometric plane F and the inclination ω that the principal ray in the on-axis focus detection optical system 15m has with respect to the principal optical axis 2 of the photographing lens are also determined by design. .

Incidentally, the amount of blur Δd in the AP luminous flux area AFP explained in FIG. 4 is Δd> when the exit pupil position is farther or closer than the conjugate position of the separator lens or aperture mask predetermined by the focus detection optical system. It becomes 0. This will be explained using FIG. 5. Separator lens 18m
If we follow the light rays from
At this time, each light ray shown by a dashed line, a solid line, and a broken line exiting from the center point R0 of the separator lens 18m passes through one point Rs=Rs, and the amount of blur becomes Δd=o. When the position Pz is closer than the AF pupil position P3 (Pz=PZ+<Ps), the light ray shown by the solid line coming out from the center point R0 of the separator lens 18M passes through the point R1 and follows the broken line. The light ray indicated by the line passes through point R1', and the light ray indicated by the one-dot chain line passes through the middle, and the amount of blur Δd>0.Exit pupil position WP of the photographic lens
When z is at a point farther than the AF pupil position '1lPs (P
z= P i > P s), a separator lens 18
The ray shown by the solid line coming out from the center point R0 of m is the point R2°
, the light ray indicated by the broken line passes through point R2, and the light ray indicated by the one-dot chain line passes through the middle, and the blur amount Δd
>0. Note that here, in order to easily represent the relationships among various parameters, it is assumed that the AFF flux regulation mask (aperture mask) of the focus detection optical system is circular, but generally speaking, it is necessary to be circular. There isn't.

Next, in FIG. 6, θ is the off-axis focus detection optical system 15.
The inclination of the principal ray ip with respect to the principal optical axis 2 in b, 11 is the amount of deviation of the off-axis ranging frame from the principal optical axis 2, and these also differ from the CCD image sensor array 16b and the separator lens 18.
b (and the aperture mask 19b in its immediate vicinity) and the geometric arrangement of the condenser lens 21b, so once the design of the camera body is completed, it becomes a unique constant.

Using the above constants, the parameter H0 explained in FIG.
, ". + d O is expressed as follows.

First, the amount of deviation H0 of the AF light flux area AFP from the principal optical axis 2 of the photographing lens is expressed as H,=h-(Pz+a)tanθ. Here, the amount of deviation h of the ranging frame from the principal optical axis 2, and the film equivalent plane F from the condenser lens 21m.
As described above, the distance a and the inclination θ of the principal ray 1p with respect to the principal optical axis 2 are body information and are constants. The exit pupil position Pz is lens information and differs for each lens.

The size of the AF beam area AFP at the exit pupil position Pz is expressed as r0=l0Q-OQ'I/2, where O is a point on the optical axis at the exit pupil position WLPz. , Q is the point farthest from the optical axis of the AF beam area AFP at the exit pupil position Pz, and Q' is the point closest to the optical axis of the AF beam area AFP at the exit pupil position Pz.

When Pz=Pz1≦Ps, in FIG.
When P z = P Z2 > P s, in Fig. 5, furthermore, the distance d0 between the AF light flux areas AFP is.

It is expressed as

In each of the above equations, 0sQs, 0sQs', Ps, and e are all body constants and are constant. Also, Pz=
Pz+ and Pzx are values specific to each lens.

As is clear from the above, the outer and inner pupil margins OUT and IN are a series of body constants Os Q s .

0sQs', Ps, e and a series of lens information Pz, Po
, Po°.

ΔP0. It is expressed by ΔP0'. By setting appropriate thresholds for the outer and inner pupil margins OUT and IN, selecting the distance measurement area within the on-axis and off-axis distance measurement frames,
Alternatively, it is possible to select a distance measurement frame when there are a plurality of distance measurement frames. To select the distance measurement area or distance measurement frame, select the outer and inner pupil margins OUT within the camera body.

Based on the method of calculating IN using the above-mentioned calculation formula and the pre-calculated results, Pz and P 6 , P-, p0
One possible method is to prepare a table in the camera body for selecting a distance measurement area by setting an appropriate threshold value for ゜poo, but the following explanation will be based on the latter standpoint.

First, an example of distance measurement area selection using a distance measurement frame located on the optical axis will be given.

Figure 7 shows the focus detection optical system 15m on the optical axis.
The Kuraray situation of the luminous flux is determined by various exit pupils Pea.

Pot';P@b,Pob';Poc,Poe';Po
d and Pad'. Here, the exit pupils p, b, p, b' are AF in FIG.
It is assumed that they match the pupil aperture QsQs'. The image A o B o on the film iso-inclined plane F is the condenser lens 2
CC with 1a and separator lens 18m+, 18a*
Images A + B + and A x B ! on the D image sensor row.
imaged as. Point A + on the CCD image sensor array,
Considering the passband of light incident on B + , A t , and B 2 , the light incident on point A is LAI ~ UAI,
The light incident on point B is from LBI to UB1, the light incident on point A is from LA2 to UA2, and the light incident on point B2 is from LB2 to
It can be seen that it has a passband of UB2. AP pupil aperture Qs
Naturally, in the exit pupils p ob , p , and b' that coincide with Qs', no curarling of the AP light flux occurs.

Figure 8 shows exit pupils P oh, P , , + :p ob,
P ob'; P Oe+Po@'; Pod, Po
In Fig. 8, which shows the element surface illuminance distribution on the CCD image sensor array corresponding to d', the horizontal axis indicates the direction in which the elements of the CCD image sensor array are arranged, and the vertical axis indicates the direction in which the elements of the CCD image sensor array are arranged. It shows the illuminance of The image sensor row R on the right side has an image A +
B + is imaged, and image A * is formed on the left image sensor row.
Assume that B* is imaged. The image sensor row on the left is
It is divided into four ranging areas ■ to ■.

When a photographic lens having exit pupils P ob and P ob' is used, neither the outer exit pupils P and b nor the inner exit pupils p and b' cause clarification of the AF light flux, so the element surface illuminance is reduced. The distribution becomes a uniform distribution E.

Therefore, in this case, all distance measurement areas (■) to (■) can be used.

Exit pupil P. a, When using a photographic lens with P6m', the luminous flux of UA2 and U
Since curare occurs in the BI luminous flux, the illuminance on the element surface near the optical axis 2 decreases, resulting in a distribution J. Also, due to the inner exit pupil P 6m', curare occurs in the LB2 luminous flux and the LAI luminous flux. As a result, the illuminance on the element surface far from the optical axis 2 also decreases, resulting in a distribution G. Therefore, the distance measurement area that can be used without being affected by the AF light flux is .

Exit pupil P. c. When using a photographic lens with Pea', the light flux of UB2 and UA are determined by the outer exit pupil Pea.
Since clarification occurs in the light beam I, the illuminance on the element surface far from the optical axis 2 decreases, resulting in a distribution G. Also, the inner exit pupil P. Since C' causes a curvature in the LA2 and LBI light beams, the illuminance on the element surface near the optical axis Z also decreases, resulting in a distribution J. Therefore, the distance measurement area that can be used without being affected by the Kuraray of the AP light beam is .

Exit pupil P. When using a photographic lens with d, P, and d', the outer exit pupil Pod causes a large deviation between the light flux of 'CUB2 and the light flux of UAI, so the illuminance of the element surface far from the optical axis 2 is greatly reduced. Therefore, the distribution becomes H, and therefore the distance measurement area ■.

■, ■ cannot be used, and also inner shots and exit P. d'' causes vignetting in the LA2 and LBI luminous fluxes, so the illuminance on the element surface near the optical axis 2 also decreases, causing the distribution J
Therefore, distance measurement area (2) cannot be used either, and in the end, there is no usable distance measurement area.

From this, tables such as Tables 1 to 4 can be created.

(Left below) Table 1 (Exit pupil position and exit pupil, selection of on-axis distance measurement area from outer diameter, - pull) In the above table, Pz: Exit pupil position Ps, AF pupil position Po: Outside exit pupil Diameter ■～■: Distance measurement area ×: Distance measurement impossible Table 2 (selection table of on-axis distance measurement area from exit pupil position and exit pupil inner diameter) In the above table, Pz: Exit pupil position Ps: AF pupil position P , ″: Exit pupil inner diameter ■～■: Distance measurement area Position Ps: AF pupil position p,: Deformed exit pupil outer diameter ■~■: Distance measurement area In the table, Pz: Exit pupil position P s: A F pupil position P,': Deformed exit pupil inner diameter ■~■: Distance measurement area ×: Distance measurement impossible The first table shows the exit pupil position P'z and In Table 1, which shows an example of a distance measurement area selection table in an on-axis distance measurement frame from the diameter P0, t, n, m, and rv indicate the distance measurement areas, and × indicates that the illuminance distribution is large. , Pol"""'P, which indicates that distance measurement is not possible. 4, Pz, ~P
z is a predetermined constant obtained from the above equation. The exit pupil P'ob described above is Pz=Ps, Pob
=OsQs, exit pupil P. a is Pzs<P
z<Pz4. When P o3< P ea< P 04, the exit pupil P'6c is Pzl<PZ< PZ2. P
In the case of ol<Poc<Pox, the exit pupils P and d correspond to the case of Pz<Pzl and Pod<Pet.

The distance measurement area for the non-reflective telephoto type can be selected from Table 1.

Further, Table 2 shows an example of a distance measurement area selection table in the on-axis distance measurement frame from the exit pupil position Pz and the exit pupil inner diameter Po°.
This applies to the case of ob'=OsQs', and the exit pupil P 6m'
is Pz3<Pz<Pz, Pos'<Poa'<Po<
', the exit pupil P 6c' is P z + < P z
< P Z 2 , P o + '< P oc'
<P. In the case of 'z', the exit pupils p, d' are Pz<P
Z,.

In the case of a 0-reflection telephoto type that corresponds to the case of P, d'<P, lo, the exit pupil outer diameter P at a predetermined exit pupil position Pz
Select the distance measurement area using Table 1 from 0, and
A distance measurement area is selected from the exit pupil inner diameter P, ゛ using Table 2, and a common distance measurement area for both of the selected distance measurement areas is finally determined.

Table 3 is an example of a table for selecting a distance measurement area in an off-axis distance measurement frame from the exit pupil position Pz and the modified exit pupil outer diameter p0. The modified exit pupil outer diameter p is on the axis (or near the axis)
Exit pupil outer diameter P0 when viewed from and outer image height correction data Δ
It is approximately determined by the following formula depending on P0 and a body constant that is partially related to the pupil position Pz.

PO"POk・ΔP0 (0≦≦1) Here, in FIG. 6, the position where the principal ray ip of the AP luminous flux intersects the optical axis 2 is Pz=Ps (AF pupil position, constant). Then, when Pz=Ps (=0), this shows that the AF light beam is not shifted with respect to the main optical axis 2, and shows that there is no influence of ΔP0 at the position where curvature is most likely to occur ( (see FIG. 4), and when Pz<Ps or Pz>PS, k approaches 1.

-m, the AF light flux area AFP of the off-axis ranging frame is shifted from the optical axis 2, so k is a parameter that changes from 0 to 0.8. The meaning of the value itself is the AF light flux area AFP of the focus detection optical system located off the optical axis, and the AF pupil position W.
This is a coefficient for changing the weighting of ΔP0 when considering the margin with the exit pupil outer diameter P0 at the exit pupil position Pz, which is significantly different from Ps.

The modified exit pupil outer diameter p0 defined in this way is used for determining the distance measurement area only in the off-axis distance measurement frame. That-
An example is shown in Table 3. The major differences from the selection of the distance measurement area in the on-axis distance measurement frame shown in Table 1 are as follows: ■For a photographic lens with a small exit pupil position Pz, even if the modified exit pupil outer diameter p0 is large, the AF luminous flux is It is easy to get angry.

■Also, for a photographic lens whose exit pupil position Pz is far away from the AF pupil position P3, the AP light flux will deviate greatly off-axis as shown in Figure 6, and the k value itself will also become large. The point is that it becomes easier to clare.

Regarding the exit pupil inner diameter Pa' for selecting the off-axis distance measurement area, the modified exit pupil inner diameter p0° is defined as poo'' Po.

+ is defined as '・ΔP,' (0≦≦1), and the above p
A similar argument can be made by replacing o with p0゛. Fourth
The table is an example of a selection table for the distance measurement area in the off-axis distance measurement frame from the exit pupil position Pz and the modified exit pupil inner diameter p0'.

FIG. 9 is a circuit diagram of a camera system to which the present invention is applied. (DT) is a light receiving part for focus detection, and 1 in Fig. 2
It has CCD image sensor arrays indicated by 6m, 16b, and 16e. (I FC) is an interface circuit that controls the operation of the CCD image sensor array, A/D converts the signal read from the CCD image sensor array, and sends it to the microcontroller (COM>) via the data bus (DBAF). It also has a function to transmit the completion of the charge accumulation operation of the CCD image sensor array to the interrupt input terminal (INTO) of the microcomputer (COM).The charge accumulation time to the CCD image sensor array depends on the subject. It is controlled by the output of a light receiving section (not shown) that monitors brightness.

(MOAF> is the lens drive motor for AF, (M
DA> is a motor control circuit, which controls forward rotation, reverse rotation, brake, and OFF using signals from the output ports (po) and (pt) of the microcomputer (COM>). (DPA) is the motor control circuit of the microcomputer (COM>). This is a display unit for displaying the moving direction of the lens, focusing, and a focus detection failure warning based on signals from the output ports (pt) and (ps).

(ENL) is an encoder that outputs pulses to monitor the amount of lens drive (motor rotation amount) by the lens drive motor (MOAF), and (ENAP) outputs pulses to monitor the amount of aperture of the lens. It is an encoder. (SEC) is the output port (p4)
When the level is Low''', the AF encoder (EN
This is a data selector for sending pulses from the aperture encoder (ENAP) to the event counter input terminal (CNTR) when the pulse is from the aperture encoder (ENAP) when the level is High. is provided with an event counter, data is preset in the event counter, the contents of the event counter are counted down every time a pulse is input to the terminal (CNTR), and when the contents of the event counter reach 0, an interrupt is generated.゛(S,) is a photometry switch that is closed at the first step of pressing the release button, and the closing signal of this photometry switch (Sl) is sent to the interrupt input terminal (INTo) of the microcomputer (COM).
is input to the human-powered boat (p,). (st) is a release switch that is closed at the second step of pressing the release button, and a closing signal of this release switch (S2) is input to the input port (p,). (SS) is a reset switch that is closed when the exposure control operation is completed and opened when winding/charging is completed, and the closing signal of this reset switch (S,) is input to the input port (p,). .

(GV) is a power supply circuit, which operates when the power supply control signal (pwc) output from the output port (p=) is at the "Los" level. This power supply circuit (GV) outputs a high voltage (HV) and a low voltage (LV) based on the output of a power supply battery (BA). High voltage (HV)
It becomes the power supply for the interface circuit (IFC) and the interface circuit (IFC).

In addition, low voltage (LV) is applied to the display unit (DPA), encoders (F, NL), (ENAP), data selector (SEC), and film sensitivity reading circuit (I), which will be described later.
SD), lens circuit (LEC), photometry and A/D conversion circuit (MEC), decoder/driver (DDR), and serves as a power source for the motor control circuit (MDA), (MDF),
The display unit (DSP>, microcontroller (COM) is powered by a battery (B).
Receives power directly from A) via the power line (EV).

(ISD) is a film sensitivity reading circuit that reads the ISO data indicating the film sensitivity on the film container, and when the film sensitivity reading circuit selection signal (C3IS) from the output port (p, ) becomes "Low" level, (
Film sensitivity data is input to the serial input terminal (SIN) in synchronization with the serial clock (SCK) from the serial clock (SCK) from
) serially. (LEC) is a lens circuit provided within the interchangeable lens. This lens circuit (L E
C) has a circuit configuration disclosed in, for example, Japanese Unexamined Patent Publication No. 59-140408, and has an output capo) (
1) The lens circuit selection signal (C9L) from +o) is “L”
ow” level, the serial clock (SCK)
Various data stored in the ROM in the lens circuit (LEC) are input to the serial input terminal (SI
N) serially. Here, the lens circuit (LE
The data fixedly stored in the ROM in C) will be explained separately for the fixed focus lens and the zoom lens.

(Leaving space below) Table 5 (Memory contents of the ROM inside the lens of a fixed focus lens) Table 6 (Storage contents of the ROM inside the lens of a zoom lens) Table 5 is for a fixed focus lens, and Table 6 is for a zoom lens. The contents stored in the ROM inside the lens are shown. address 0
1 contains the data common to all lenses as the mounting signal (IC).
It is fixedly stored as P). Address 02 is the open aperture value (Avo), address 03 is the maximum aperture value (Av)
max) is fixedly stored. In the case of a zoom lens whose aperture value changes with zooming, the aperture value at the shortest focal length is fixedly stored. Furthermore, in the case of a reflective telephoto lens, the aperture is fixed, so Avo=Ave+ax. Address 04 for fixed focus lenses;
In the case of a zoom lens, focal length (f) data is stored in addresses 10 to IF. In addition, in the case of a zoom lens, the lower 4 bits of addresses 10 or more O-
F is designated as artless by a signal obtained from the zoom encoder in response to zooming. A coefficient (K) for converting the defocus amount into the drive amount of the lens drive motor (MOAF) is stored at address 05 or addresses 20 to 2F. At address 06 or addresses 30 to 3F, data on the amount of aperture change (ΔAy) due to zooming is stored, and in the case of a fixed focus lens, it is ΔAv-0. Address 07 or addresses 40 to 4F contain exit pupil position (Pz) data, address 08 or addresses 50 to 4F.
5F stores data on the exit pupil outer diameter (Pa). Address 09 stores data on the exit pupil inner diameter (P/°), and for lenses other than reflective telephoto lenses, P/°
:=0. address OA or address 60 ~
6F stores external image height correction data P0, address OB stores internal image height correction data ΔP0', and for lenses other than reflective telephoto lenses, internal image height correction data ΔP,
"=0.

(DSP) is a display circuit, which performs display based on display data sent from a microcomputer (COM).

(M E C) is a photometry and A/D conversion circuit, and when the power supply of low voltage (LV) from the power supply circuit (GV) is started, it starts photometry operation and outputs )
When the A/D conversion enable signal (ADEN) from the A/D conversion enable signal (ADEN) becomes "Low" level, A/D conversion is repeated at a constant cycle.

Then, when the photometry and A/D conversion circuit selection signal (C3ME) from the output port (p,) becomes “Los” level, the A/D converted and latched data is output to the serial clock (SCK). Synchronize with microcontroller (COM)
sent to. (DDR) is a load driving circuit that decodes data sent from a microcomputer (COM) through a data bus (DBDR) and drives a load according to the decoded result.

The loads include a release magnet (RLM), an aperture control magnet (APM), and a leading curtain control magnet (
ICM), rear curtain control magnet (20M), film advance and exposure control mechanism charging motor (MOCH)
and its driver (MDF>).

X is an oscillator.

The operation of this camera system will be explained below based on the flowcharts shown in FIGS. 10 to 16. In the following explanation, the symbol "#0" means the step number of the program. When the release button is operated, the photometry switch (Sl) is set by pressing the first step, and the interrupt input terminal ( An interrupt signal is input to INTO), and the microcomputer (COM) executes the interrupt routine INT in Figure 10.
, starts the tangle operation. First, the power supply control signal (PWC) output from the output port (p,) is set to Lo@“ level to operate the power supply circuit (GV) (#1). Next, the interface circuit (IFC) and display circuit (DSP
), outputs the reference clock (CKO, -UT) to the photometry and A/D conversion circuit (MEC'), and performs the COD initialization operation to flush out the charge accumulated in the COD (#2゜#3) 0 Next, the charge accumulation operation of the COD is started, and when the charge accumulation operation is finished, the interrupt input terminal (INT
, ) can be accepted, and the output port (p+yi)
The A/D conversion permission signal (ADEN) from the
6).

Next, the process moves to the photometry routine, and lens data is acquired from the interchangeable lens, and film sensitivity data (IS) is acquired from the film container.
0 data) respectively (#7, $8), then,
The states of the flags IFF+ and IFFt are determined. IFF is a flag that is set to 1 when the in-focus state is reached, and IFF is a flag that is set when photometric data is taken in after the in-focus state is reached. Therefore, when the camera is out of focus or when the photometric data is not captured even though it is in focus, the photometric data is captured, and when the data is captured after the focus is focused, the flag IFF is set.
Set □ to 1 and proceed to the calculation routine. Further, if the flags IFF+ and IFF2 have the same number 1, the process directly proceeds to the calculation routine without inputting photometric data (#9 to F13).

In the calculation routine, first, in step #14, it is determined whether or not the lens attachment signal ICP is input. If so, the process moves to step #15, and if not, the process moves to step #16. In step #15, the open aperture value Avo and the maximum aperture value Avmax are equal (A vo-
If it is a reflective telephoto lens, AvoAvmax is #16, Avo-1x.
If it is Avsoax, it is a normal interchangeable lens, so move on to step #19. First, when no lens is attached or when a reflective telephoto lens is attached, aperture control is of course impossible, and the aperture must be regarded as fixed.

Therefore, in step #16, (photometric data) = Bv
- Exposure time Tv is calculated by adding ISO value Sv indicating film sensitivity to AV (BV is subject brightness, Av is fixed aperture value). Then, in step #17, it is determined whether or not a lens is attached, and if a lens is not attached, the exposure time is displayed in step #18, and the F
The value is displayed as a warning (for example, "-1"). On the other hand, if the lens is attached, it is a reflective telephoto lens, and the calculated exposure time Tv and fixed aperture value (open aperture value Avo
= maximum aperture value Av+5ax) is displayed in step #21. When it is determined in step #15 that it is not a reflective telephoto lens, in step #19, (2N! optical data) = Bv - (Avo + ΔAv), Avo + ΔAv + S
v is added to calculate the exposure value Ev, and based on this exposure value Ev, program exposure calculation (#20) is performed to calculate the aperture value Ay and exposure time Tv, and this is displayed (#
21).

When the above operations are completed, flag AEF is set to 1. This flag is a flag that is set to 1 when the exposure calculation is completed. Next, determine the state of the flag CF,
If it is CF-1, the process moves to the AF routine. This flag C
When the charge accumulation operation of the COD is completed during the operation of the photometry routine or calculation routine, if no exposure calculation has been completed, F will import the data from the COD and then perform the remaining exposure calculations. and then transition from this step to the AP routine.

In step #24, it is determined whether the release switch (S2) is closed, and in step #25, it is determined whether the exposure control value has been calculated from the photometry data after focusing. If so, the camera moves to the exposure routine and performs exposure control operations.

On the other hand, if the conditions are not met, it is determined in step #251 whether the photometry switch (S -) is closed, and if it is closed, the process returns to the photometry routine, and if it is not closed, it is stopped. Perform routine actions.

In the stop routine, first, all the flags are reset, the output port (p4) is set to the "Low" level, data is sent to the display circuit (DSP) to set the display to 0FF (nothing is displayed), and the motor (MOAF ), stops the output of the reference clock (CKOUT), deactivates the power supply circuit (GV), and sets the signal (ADEN) to High.
” A/D conversion is disabled as a level, and microcomputer (CO
M) stops its operation (#26 to #32).

Next, the operation of the AF routine will be explained using FIG. 11. When the COD accumulation operation is completed, an interrupt input signal is input from the interface circuit (IFC) to the interrupt input terminal (NTI>), and the operation from #39 is performed.
In step 39, it is determined whether or not an interchangeable lens is attached. If it is attached, the process moves to step #40, and if it is not attached, the process moves to step #51, which will be described later.
In step #40, data acquisition from D, focus detection, lens drive operation, etc. are not performed.
Analog signals corresponding to the three columns of CCDs output from the interface circuit (IFC) are sequentially A/D
Convert it and import it into the microcomputer (COM), set flag CF to 1, determine whether flag AEF is set to 1, and if flag AEF is set to O, start the first photometry. Since the routine and calculation routine have not ended, the process returns to the return address (INT, the execution step when the interrupt occurred). Then, when the photometry routine and calculation routine are completed, CF=1 is determined in step #23, and the process returns to the AF routine. If AEF=1 in step #42, the process moves to the AP routine immediately after the capture of ccD data is completed.

In the AP routine, first set the flag CF to 0,
The process moves to subroutine 5UB1 shown in FIG. 13. In this subroutine 5OB1, a distance measurement area where focus detection is possible is selected in the on-axis distance measurement frame A based on the exit pupil position Pz and the exit pupil outer diameter P0.Next, in step #44, the distance measurement area from the lens is selected. Exit pupil outer diameter P0 and outer image height correction data Δ
Off-axis ranging frame B from P6 and camera body constant k
, C is calculated.Next, the process moves to subroutine 5UB2 shown in FIG. 14, and the off-axis distance measurement frame B, Next, in step #45, the exit pupil inner diameter p,'
Determine whether = o, p,' =.

If so, it is a normal lens, and the process immediately proceeds to step #47. On the other hand, if P,'≠O, it is a reflective telephoto lens, and the process moves to subroutine SUB or 3 shown in FIG. In subroutine 5UB3, exit pupil position 11
Based on the data of Pz and the data of the exit pupil inner diameter P,', a distance measurement area in which the focus can be detected is selected in the on-axis distance measurement frame A. 8 Next, in step #46, the exit pupil inner diameter P, ゛ from the lens and the inner image height correction data Δ are determined.
Calculate the modified exit pupil inner diameter Po゛ from Po° and the camera body constant 0 Next, the process moves to subroutine 5UB4 shown in FIG. 16, and the exit pupil position Pz and the modified exit pupil inner diameter P are calculated.
A detectable ranging area is selected from the off-axis ranging frames B and C from o゛, and the ranging area selected in subroutine 5tJB2 and also selected in subroutine 5UB4 is finally determined. do.

In step #47, data PZ, P regarding exit pupils are
Based on O, PO', and PO1FO', it is determined whether or not there are any distance measurement areas selected. If there are no distance measurement areas, focus detection is not performed and the process moves to step #51. On the other hand, if even one distance measurement area is selected, focus detection (detection of defocus amount) is performed for each selected distance measurement area (#48), and reliability is determined for each distance measurement area. Determine whether certain data is obtained, and if all data is unreliable, move to step #51 (#
49, #50), and the flag lFF2 in steps #51.
Set to 1. This is to enable exposure control operation to be performed regardless of whether or not focus is achieved when focus cannot be detected. Then, a warning message indicating that detection is impossible is displayed, COD accumulation operation is started, and I N T
Allows the + interrupt and returns to the return address in the photometry routine and calculation routine.

If it is determined in step #50 that even one piece of reliable data has been obtained, the process moves to step #60 and performs statistical processing. There is processing such as employing a signal, or when a plurality of data are within a predetermined defocus amount, employing a defocus amount such that the plurality of subjects fall within the depth of focus. Then, it is determined whether the defocus amount determined by the statistical processing is within the in-focus area, and if it is outside the in-focus area, the process proceeds to step #62, and if it is within the goldfish area, the process proceeds to step #70. In step #62, the defocus direction is displayed,
Multiply the defocus amount by the conversion coefficient (K) to calculate the drive amount of the lens drive motor (MOAF) #63), preset this drive amount in the event counter (EVC) (#64), and , enable event counter interrupt #65), and operate the lens drive motor (MOAF>) (#66).

Then, the process returns to the return address of the photometry routine and calculation routine. Thereafter, while driving the lens, the photometry routine and the calculation routine are repeated, and the pulse from the encoder (ENL) that monitors the amount of lens drive is sent to the selector (S
The data is input to the event counter from the terminal (CNTR) via the terminal (EC), and the contents of the event counter are decremented.

When the content of the event counter reaches O, an interrupt (EVC interrupt) is generated by the event counter, and #1 in Fig. 12 is generated.
Perform the operation from step 00.

In step #100, it is determined whether AF is in operation or not. In this case, since AF is in operation, the process moves to step #1゜1, stops the motor (MOA F ), and performs focus detection for confirmation. In order to do this, the CCD storage operation is started (#102), and an interrupt from the interrupt input terminal INT is enabled (#103), and then the photometry routine starts from step #7. Note that step #104 will be described later.

In the flow of FIG. 11, when it is determined that focus is achieved in step #61, the process moves to step #70,
In-focus display is performed, and flag I is set in step #71.
Set FF to 1 and proceed to the photometry routine from step #7. Therefore, once the state of the goldfish is confirmed, focus detection and lens driving will not be performed thereafter as long as the photometry switch (S,) is closed.

At step #24 in Fig. 10, press the release switch (S
, ) is closed and the flag IFF is set to 1 in step #25, the process moves to the exposure control routine shown in FIG. First, set the AP display to 0F in step #75.
FL, use the release magnet (RLM) at step #76.
) to start the operation of the exposure control mechanism. Then, it is determined whether an interchangeable lens is attached and whether a reflective telephoto lens is attached (#77, #78) l,
, If no lens is attached or a reflective telephoto lens is attached, the process moves to step #83 and no aperture control operation is performed.On the other hand, if a normal lens is attached, first step #79 is performed. It is determined whether the control aperture value (AV) is equal to the open aperture value (Avo), and A v ==
If A vo, the process similarly moves to step #83. On the other hand, if Av≠Awo, the number of refinement stages (Av-A
vo) is set in the event counter (EVC), the port (p,) is set to "High" level, and the pulse from the encoder (E N A P ) that monitors the aperture amount is output from the selector (SEC). to (
#80. #81. #82) Then, wait for a certain period of time in steps #83 and #84. During this time, the aperture operation is performed and when an event counter interrupt occurs, the aperture magnet (APM) is activated in step #104. Stop filtering. Then, after a certain period of time has passed, the reflection mirror has finished rising and the leading curtain magnet (IC
M) to start running the leading curtain and count the exposure time (#85, #86). When the count is finished, operate the trailing curtain magnet (2CM) and start running the trailing curtain. (#87), and wait for the trailing curtain to complete running and the reset switch (S,) to be turned ON (
#88), when the reset switch (S, ) is turned on,
Operate the charging motor (MOCH) to wind the film and charge the exposure control m mechanism, and wait until this operation is completed and the reset switch (S3) is turned OFF (#89° #90) , and when the reset switch (S,) turns OFF, release your finger from the release button and wait for the photometry switch (S,) to turn OFF (#91>, when the photometry switch (S+) turns OFF,
Perform the stop routine, then turn the metering switch
S, ) is turned ON and the operation is stopped until the microcomputer (COM) is activated.

Subroutines 5UBI, 5OB2, 5 shown in FIG.
The specific contents of UB3, 5UB4 are shown in FIGS. 13, 14, 15, and 16, respectively. In the subroutine 5UB1 of FIG. 13, the exit pupil position P2 is set according to Table 1.
and exit pupil outer diameter P. A distance measurement area is selected from within the on-axis distance measurement frame A. First, in step #110, p
, <p. , and P, <P. In the case of I, there is no detectable ranging frame, and the process moves to step #128.

On the other hand, if P0≧PoI, then in step #111 it is determined that P o< P ox and P 02> P o≧P
If it is eI, Y++ is set as the address in step #112.

Similarly, Pos>P at step #113.

If ≧P02, set Y I 2 as the address in step #114, and set P114> in step #115.
P.

If ≧PO3, set Y12 as the address in step #116, and P0≧PL in step #115.

If so, Yl4 is set as the address in step #117.

Next, the exit pupil position Pz is also determined in the same manner according to Table 1, and if Pz≧Pz in step #118, the process moves to step #128, and in step #118, PZ4>PZ If ≧PZ3, set X I 4 as the address in step #120, and if PZ3>PZ≧Pzl in step #121, set X in step #122.
Set ls to address, and set P z in step #123.
If z＞P z≧Pzl, set X in step #124.
12 as the address, and in step #123 P z
, > P z, set Xl as the address in step #125. As a result, the position in Table 1 can be set using the address data (XII, Yl), and this address data (X port, 7 port) can be used to set the position in the first table.
The ROM table in which the table is stored is specified, and the data of the distance measurement area where the focus can be detected stored there is set in the register ERAR. This data is from distance measurement area I~
The data is 4 bits corresponding to (2), and the bit corresponding to the distance measurement area where focus detection is possible is 1, and the bit corresponding to the distance measurement area where focus detection is not possible is 0. Therefore, for example, address data (X + +, Y
+ + ) is specified, “0001” or 001
1" data, address data (Xl,, Yl,) is specified, data "0001" or "1001",
When the address data (X + + , Y l 4 ) is specified, data "1111" is set in the register ERAR. Also, in step #128, since there is no ranging area where focus can be detected, the register ER
“0000” is set in AR.

The subroutine 5UB2 in FIG. 14 is a flow for selecting a focus detectable distance measurement area from the off-axis distance measurement frames B and C from the exit pupil position rIIP z and the modified exit pupil outer diameter p0 according to Table 3. be. Subroutine 5 in Figure 13
Similar to UB1, in step #130 P O < P
01 or in step #138, Pz≧Pz,
In this case, there is no distance measurement area in which the focus can be detected, so 0000n is set in the register ERBCR. Furthermore, #13
p in step 1. I≦Pa<P. If 2, #132
Set Y21 as the address in step #133, and set p in step #133. 2≦p 0 (if p 0., set Y2□ as address in step #134, po in step #135, if ≦p o < P o 4, set #13
Set YB as the address in step 6, set po in step #135, and if ≦p0, set Y in step #137.
2. Set the address. Furthermore, if PZ3≦PZ<PZ4 in step #139, set X24 as the address in step #140, and set PZ3 in step #141.
If Z2≦Pz<Pzs, set X2 in step #142.
3 as the address, and in step #143 PzI≦
If P z < P Z 2, set X2□ to the address in step #144, and set Pz in step #143.
, )Pz, set X21 as the address in step #145. Then, the set address (X*+
, Yzt) to specify the ROM table, and set the data stored at that address in the register ERBCR.

In the subroutine 5UB3 shown in FIG. 15, the exit pupil position Pz and the exit pupil inner diameter P are determined according to Table 2. Select the distance measurement area in the on-axis distance measurement frame A where the focus can be detected from Select a distance measurement area where focus can be detected. First, according to Table 2, address data (X31.Y3) is set (#
151 to #166), and this address data (X
31゜Y31) specifies the ROM table, reads the data stored at that address, and performs the AND of this data with the data already set in the register ERAR in subroutine 5UB1 for each bit.
This result is set in register ERAR. As a result, even if one bit is selected and the bit corresponding to that distance measurement area is 1, if the other bit is 0, that bit becomes 0, and the exit pupil outer diameter P. , and the exit pupil inner diameter P0° will be set in the register ERAR. Note that P0°≧P0. ° or when Pz<Pz+, there is no ranging area where focus can be detected, so the register ERAR
is set to “oooo”.

4. In subroutine 5UB4 of FIG. 16, according to Table 4, from the exit pupil position Pz and the modified exit pupil inner diameter p0', select a distance measurement area in which the focus can be detected from among the off-axis distance measurement frames B and C; Finally, from both the modified exit pupil outer diameter p0 and the modified exit pupil inner diameter Po°, a distance measurement area in which the focus can be detected using the off-axis distance measurement frames B and C is selected. First, similar to subroutines 5UBi to 5UB3 in FIGS. 13 to 15,
Address data (X411Y41) is set according to the size of po' and Pz, and this address data (X41
, Y41) specifies the ROM table, reads the data stored at this address, and stores this data in register ERBC already in subroutine 5UB2.
By performing an AND with the data set in R for each bit and setting this result in register ERBCH,
Finally, the distance measurement area where the focus can be detected is set, where p0°≧p. , ', there is no ranging area where the focus can be detected, so the register ERBCH contains "ooooo".
”.

In the above embodiment, the on-axis ranging frame A and the off-axis ranging frames B and C are provided as ranging frames, and each ranging frame A, B, and C is assigned to the ranging areas ■ to ■. Although the distance measurement frames are divided into areas, for example, only the distance measurement frames A and B or only the distance measurement frames A and C may be used.
Further, it is also possible to divide the range-finding frame A into areas as in the embodiment, with only the range-finding frame A, or to provide three range-finding frames A, B, and C and set the range-finding frame A as the range-finding frame A. It may be configured such that the distance measurement frames B and C are not divided into regions.

As exposure control modes, only P mode (program exposure mode) is shown, but A mode (aperture priority AE mode), S mode (shutter speed priority AE mode),
Even in M mode (manual mode), when a reflective telephoto lens is attached, different measures are required than when using a normal lens. That is, in A mode, the exposure time is automatically set for a fixed aperture as in P mode, and in S mode or M mode, the exposure time is set for a fixed aperture.

Furthermore, the interchangeable lens of this embodiment stores data regarding the exit pupil in order to determine whether focus detection is possible, but data indicating whether the lens is capable of focus detection is also output. In this way, it is possible to correspond to a conventional camera having a focus detection function, but not having a function of determining whether or not focus detection is possible based on data regarding the exit pupil.

(Effects of the Invention) In the lens interchangeable focus detection system according to the present invention, based on data regarding the exit pupil from the interchangeable lens,
It is determined whether the focus detection means is capable of optically accurate focus detection, and if focus detection is possible, the focus detection means is activated, so that the distance measurement area is located outside the optical axis of the interchangeable lens. Even when the lens is set to The effect is that it can be done.

In addition, the interchangeable lens according to the merged invention permanently stores data regarding the exit pupil diameter, exit pupil position, and image height correction that are unique to the lens, and stores these data on the body based on the read signal from the body. Therefore, in a body equipped with this interchangeable lens, it is possible to calculate the change in the exit pupil diameter when viewed from off-axis based on the above data, and This has the effect of being able to determine with high precision whether or not there is Kurare in the luminous flux.

[Brief explanation of the drawing]

FIG. 1 is a schematic configuration diagram of the present invention, FIG. 2 is a perspective view of a focus detection system according to an embodiment of the present invention, FIG. 3 is a perspective view showing the configuration of the main parts of the same as above, and FIG. FIG. 5 is an explanatory diagram of the exit pupil plane of the interchangeable lens used. FIG. 5 is an explanatory diagram of pupil-related constants of the focus detection optical system used in the same. FIG. 6 is an explanatory diagram of the off-axis focus detection optical system used in the same. FIG. 7 is an explanatory diagram of the on-axis focus detection optical system used in the above, FIG. 8 is a diagram showing the illuminance distribution on the CCD image sensor array used in the above, and FIG. 9 is a circuit diagram of a camera system using the same focus detection system. , FIG. 10 to FIG. 16 are flowcharts for explaining the operation of the same. 1 is an optical means, 2I, 2 is a light receiving means, 3 is a focus detection means, 4 is a discrimination means, 5 is an operation permission means, 6 is a storage means,
7 is a read signal input means, and 8 is a data sending means.

Claims (4)

[Claims] (1) Optical means that divides the light beam from the subject in an area that does not include the optical axis of the interchangeable lens into a pair of light beams that pass through different areas of the exit pupil plane of the interchangeable lens, and forms a pair of optical images from the light beams. a light receiving means for receiving the pair of light images; a focus detection means for detecting the focus of the interchangeable lens by detecting the relative displacement of the pair of light images based on the output of the light receiving means; a determination means for determining whether or not the focus detection means can perform optically accurate focus detection from a combination of the optical means and the optical system of the interchangeable lens, based on data regarding the exit pupil of the lens; and a means for operating a focus detection means, if any. (2) Data regarding the exit pupil from the interchangeable lens is data regarding the exit pupil diameter, exit pupil position, and image height correction, and the determining means determines whether a combination of these data satisfies a predetermined condition. 2. The lens-interchangeable focus detection system according to claim 1, wherein the lens-interchangeable focus detection system is a means for. (3) The determination means calculates data of the modified exit pupil diameter as seen from outside the optical axis of the interchangeable lens, based on the exit pupil diameter from the interchangeable lens, data regarding image height correction, and data determined by the optical means. and means for determining whether the data on the modified exit pupil diameter and the exit pupil position satisfy a predetermined condition. formula focus detection system. (4) A storage means for fixedly storing data specific to the lens, a means for inputting a reading signal from the body, and a means for sequentially sending the data stored in the storage means to the body based on the reading signal. The data stored in the storage means includes the exit pupil diameter of the lens, the exit pupil position,
An interchangeable lens characterized by including data regarding image height correction.