JPS63286808A - Focus detecting system for reflex telephoto lens and reflex telephoto lens - Google Patents

Abstract

PURPOSE:To obtain a reflex telephoto lens which is low in cost and compact in constitution and never produces vignetting of lens, by properly discriminating the propriety of focus detection in accordance with data related to the outer and inner diameters and position of an exit pupil read from the lens. CONSTITUTION:A focus detecting means 3 discriminates whether or not optically correct focus detection is possible in accordance with data related to the outer and inner diameters and position of an exit pupil from a reflex telephoto lens ML. Since an operation permitting means 5 actuates the focus detecting means 3 if the discriminated result is 'yes', whether focus detection is possible or not can be discriminated properly even when the reflex telephoto lens ML is used. Moreover, data related to the outer and inner diameters and position of the exit pupil inherent to the lens ML are stored in a fixed state and the data are sent to the camera body side in accordance with read signals from the body side. Therefore, a focus detecting system using an inexpensive compact reflex telephoto lens can be realized and whether focus detection is possible or not can be discriminated.

Description

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

(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 AF pupil through which the AF light beam used for focus detection passes is determined by the design of the camera body. For example, no currant occurs in the AP light flux, and this does not interfere with the focus detection operation. However, the position and size of the exit pupil of the interchangeable lens are not constant, and if the AF@ moves away from the exit pupil, the AP Claret may appear in the luminous flux. At this time, there was an r:4 problem in which a focus detection error occurred or the focus became impossible to detect.

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 exit pupil is restricted even inside, such as in a reflective telephoto lens.

Reflective telephoto lenses have great advantages of being inexpensive and compact, and it is desired that focus detection or automatic focus adjustment can be performed even when the reflective telephoto lens is attached to a camera body. There are conventional reflective telephoto lenses on the market that can be attached to single-lens reflex cameras equipped with TTL phase detection AF functions, but even when attached to the camera body, the lens information is not transferred to the camera body. It was not configured to transmit data, and the camera's AF function did not work.

(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 focus detection is possible depending on the open aperture value of the lens used. However, if the lens used is a reflective telephoto lens, the luminous flux is restricted even inside the exit pupil, so there is a problem that it is not possible to correctly determine whether focus detection is possible using only the open aperture data. be.

The present invention has been made in view of these points, and its purpose is to perform focus detection based on data regarding the exit pupil outer diameter, exit pupil inner diameter, and exit pupil position read from a reflective telephoto lens. An object of the present invention is to provide a focus detection system for a reflective telephoto lens and a reflective telephoto lens that can correctly determine whether or not the lens is available.

(Means for Solving the Problems) In order to achieve the above object, in the focus detection system for a reflective telephoto lens according to the present invention, as shown in FIG. an optical means 1 for forming at least one pair of light images from light beams from at least one pair of different areas on an exit pupil plane; at least one pair of light receiving means 21 and 22 for receiving the light images; and at least one pair of light receiving means 21 and 22 for receiving the light images. At least one focus detection means 3 that performs focus detection by detecting the relative displacement of the optical image based on the outputs of the means 2+ and 2g, and an exit pupil outer diameter and an exit pupil inner diameter read from the reflective telephoto lens ML. and determination means 4 for determining whether or not the focus detection means 3 is capable of optically accurate focus detection based on the combination of the optical system of the optical means 1 and the reflective telephoto lens ML, based on the data regarding the exit pupil position. and an operation permission means 5 for operating the focus detection means if focus detection is possible.

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 the reflective telephoto lens according to the combined invention, the first
As shown in the figure, it is a reflective telephoto lens ML attached to a camera body having a focus detection means 3, and a storage means 6 that fixedly stores data specific to the lens, and a read signal from the camera body is input. and a data transmitting means 8 that sequentially transmits the data stored in the storage means 6 to the camera body based on the read signal, and the data stored in the storage means 6 includes It is characterized in that it includes data regarding the exit pupil outer diameter, exit pupil inner diameter, and exit pupil position of the lens.

(Operation) The operation of the present invention will be explained with reference to FIG. Regarding the focus detection system for the reflective telephoto lens shown on the right side of FIG. 1, the optical means 1 forms at least one pair of light images from the light beams from at least one pair of different regions of the exit surface of the reflective telephoto lens ML. The light receiving means 21 and 22 then receive this optical image. The focus detection means 3 detects the focus by detecting the relative displacement of the optical image based on the output of the light receiving means 23.2□.The zero discrimination means 4 detects the exit pupil outer diameter read from the reflective telephoto lens ML. , the exit pupil inner diameter, and the exit pupil position (
Based on this data, it is determined whether the focus detection means 3 can perform optically accurate focus detection based on the combination of the optical system of the optical means 1 and the reflective telephoto lens ML. The operation permission means 5 operates the focus detection means 3 if focus detection is possible. therefore,
This focus detection system for a reflective telephoto lens reads data regarding the exit pupil outer diameter, exit pupil inner diameter, and exit pupil position from the reflective telephoto lens ML, while also taking into account the exit pupil limitations on the inside. , it is possible to correctly determine whether or not optically accurate focus detection is possible.

Next, regarding the reflective telephoto lens ML 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. Since the data stored in the storage means 6 includes data regarding the exit pupil outer diameter, exit pupil inner diameter, and exit pupil position of the lens, it is possible to accurately inform the body of the exit pupil light flux passing range. It is something that can be done.

(Example) Fig. 2 is a diagram showing a schematic configuration of a multi-point distance measurement module installed in a single-lens reflex camera. , 15 is a focus detection optical system. 22 is a field stop arranged near the focal plane, and has a rectangular opening 22a,
Has 22b, 22c, 21m, 2 lb, 21
c is a condenser lens, 20 is a module mirror, 18
a, 18b, 18c are separator lens pairs, 16m, 1
Reference numerals 6b and 16c are CCD image sensor arrays arranged on the focal J and % planes 17 of the separator lens. One is an aperture mask, which has circular or oval openings 19a, 19b, and 19c. The image whose field of view is limited by the rectangular aperture 22a passes through the condenser lens 21&, and then the field diaphragm 1
9a and a pair of separator lenses 18a, the images are projected onto the CCD image sensor array 16a as two images. When the image interval between these 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 bin is in focus, and when it is wider than the predetermined interval, it is determined that the rear bin is in focus.

Similarly, the images of the field stops 19b and 19c 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 21a, a pair of separator lenses 18a, and a CCD image sensor array 16m) located above the optical axis 2 in FIG. Optical system 15b (combination of condenser lens 21b, separator lens pair 18a, and CCD image sensor array 16b) is extracted.

The distance measurement frames A and B are the focus detection frames shown on the film equivalent 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 18a 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, P and z are the exit pupil positions, which mean the distances between the film equivalent plane F and the exit plane of a given 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.

ΔP0 is a parameter for correcting the shape of the outer exit pupil when viewed from a predetermined image height position. ”).

Poo 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
' are not necessarily located at the same exit pupil position in terms of -JR, but in the following explanation, they are assumed to be located 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 (abbreviated as "inner image height correction data"), is usually circular, but as the image height on the film surface increases, Therefore, as shown by the broken line in FIG. 4, the shape is close to an ellipse. ΔP.

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 AF light flux area AFP from the principal optical axis 2 of the photographing lens, and in the case of the focus detection optical system 15m located on the optical axis, the deviation amount l]. =0.

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

do represents the distance between the two AF beam 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 % In particular, in the case of the focus detection optical system 15a on the axis, normally H
0=0, ΔP0=0, and OU Tz=Poro 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.

lN-1(HO+ΔP0°)”+(do-Δa/2)2
+1/2-re-P,.

In particular, in the case of the on-axis focus detection optical system 15a, 14°=
0, ΔP0-0, and I Nz=d, -Δd/2 r o -P o.

Depending on the sign of the outer and inner pupil margins JiOUTjN, 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 film equivalent surface F.

1 is a separator lens 1 from a condenser lens 21a.
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 "AF pupil") 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. .

O5 is a point on the optical axis at AF@position Ps, and Qs
Qs' is the AP pupil aperture.

The AF pupil position Ps and the AF pupil aperture QsQs' are determined by the power of the condenser lens 21a and the above-mentioned distances gi a , t
It is uniquely determined by design. Therefore, the distances 0sQs' and 0sQs from the point Os on the optical axis to the farthest point Qs and the nearest point Qs'' of the AF pupil aperture QsQs' can be regarded as constants.Furthermore, the size of the distance measurement frame on the film equivalent plane F e, and the inclination ω that the principal ray in the on-axis focus detection optical system 15a has with respect to the principal optical axis 2 of the photographing lens.
Determined by design.

Incidentally, the amount of blur Δd in the AF beam 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 18a
If we sequentially follow the light rays from , passing through the condenser lens 21a and the exit pupil of the photographing lens, the exit pupil position Pz=Ps
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 18a passes through one point Rs=Rs', and the amount of blur Δd=o. Furthermore, when the exit pupil position Pz of the photographing lens is closer to the AF pupil position Ps (Pz=Pz, <Ps), the light ray shown by the solid line emerging from the center point R0 of the separator lens 18a is a point. The light ray shown by the broken line passes through R1', the light ray shown by the dashed line passes through the middle, and the blur amount Δ
d>O. When the exit pupil position Pz of the photographic lens is located at a point farther than the AF pupil position Ps (PZ=PZ2>PS)
, the light ray shown by the solid line coming out from the center point R0 of the separator lens 18m passes through point R2°, the light ray shown by the broken line passes through point R2, and the light ray shown by the dashed line passes between them. , the amount of blur Δd>O. Here, in order to easily express the relationship between various parameters, it is assumed that the AF light flux regulating mask (aperture mask) of the focus detection optical system is circular; however, in -a, it is circular. There's no need.

Next, in FIG. 6, θ is the off-axis focus detection optical system 15.
The inclination of the principal ray 1p with respect to the principal optical axis 2 at b, h is the amount of deviation of the off-axis distance measuring frame from the principal optical axis 2, and these also differ from the CCD image sensor array 16b and the separator lens 18b.
(and the aperture mask 19b in the 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.
, “., −〇 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: Ho=h - (Pz+a)tanθ. Here, the amount of deviation 11 of the ranging frame from the principal optical axis 2, the distance a from the condenser lens 21m to the film equivalent surface F, and the inclination θ of the principal ray ip with respect to the principal optical axis 2
As mentioned above, is body information and is a constant. The exit pupil position WtPz is lens information and differs for each lens.

The size of the AF light flux area AFP at the exit pupil position Pz is It is expressed as ro= l OQ OQ' l / 2.

Here, 0 is the point on the optical axis at the exit pupil position raPz, Q is the farthest point from the optical axis of the AF beam area AFP at the exit pupil position 3Pz, and Qo is the point on the AF beam area AFP at the exit pupil position Pz. This is the point closest to the optical axis.

When Pz=Pz, ≦Ps, in FIG.
When Pz=Pza>Ps, in Figure 5, OQ' = 02Q2' = (OsQs'--!-) Fall+
-'-2Ps2 10. r. --l (OsQ s-.sQ s' +
e)! -' + e 12
Ps Furthermore, the distance d0 between the AP luminous flux area AFP is expressed as Pz d0=(o Qs+OQs')□Ps.

In each of the above equations, 0sQs, 0sQs', Ps, and e are all body constants and are constant. Also, Pz=
Pz1. Pz2 is a value specific to each lens.

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

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

ΔP0. It is expressed by ΔPo'. By setting appropriate thresholds for the outer and inner pupil margins JiOUT and IN, you can select the ranging area within the on-axis and off-axis ranging frames, or the ranging frame when there are multiple ranging frames. A choice can be made. To select the distance measurement area or distance measurement frame, select the outer and inner pupil margins OUT within the camera body.

Pz, Po, Poo, Po based on the method of calculating IN using the above-mentioned calculation formula and the result of the calculation in advance.

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 p0', but the following explanation will be based on the latter perspective.

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

FIG. 7 shows the focus detection optical system 15a on the optical axis.
Various injection @poa of Kuraray situation of luminous flux.

P, a';Pob,Pob';Poc,P,c'
; This is a photographic lens having Pad and Pod'. Here, it is assumed that the exits @p, b, p, and b' correspond to the AF pupil aperture QsQs' in FIG. The image A o B o on the film iso-inclined plane F is the condenser lens 21a and the separator lenses 18m+, 18a
Images A + B + and A are formed on the CCD image sensor array by t.
, B2. Point A + on the CCD image sensor array
, B I , A z , B 2 Considering the passband of the light incident on point A1, the light incident on point A1 is LAI ~ UA
The light incident on I, point B is LBI to UB1, the light incident on point A2 is LA2 to UA2, and the light incident on point B2 is LB
It can be seen that it has a pass range of 2 to UB2. AF [l!
Exit pupil P coincident with aperture QsQs'. Of course, at points b, p, and b', no clutter occurs in the AF light beam.

Figure 8 shows injection @p oa, P oa'; P ob, P
ob'; pac.

In FIG. 8, which shows the element surface illuminance distribution on the CCD image sensor row corresponding to Poc'; Pod, Pod', the horizontal axis indicates the direction in which the elements of the CCD image sensor row are arranged, and the vertical axis indicates the illuminance on each element surface. I on the right
It is assumed that images A and B are formed on the first image element row R, and images A and B are formed on the left image sensor row. The image sensor row on the left side is divided into four distance measurement areas (■ to ■).

When using a photographic lens with exits @P ob and P ob', neither the outer exit pupil Pob nor the inner exit pupils @ P and b' cause curariness of the AF light flux, so the element surface illuminance distribution is A uniform distribution E is obtained.

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

When using a photographic lens having exit pupils P 6a and P 6a', the exit pupil P is the outer one. Because of a, clarification occurs in the luminous flux of UA2 and the luminous flux of UBI, so the illuminance of the element surface near the optical axis 2 decreases, resulting in a distribution J. Also,
Inner exit pupil P. By ao, the luminous flux of LB2 and LAI
Since curare occurs in the luminous flux, the illuminance of the element surface far from the optical axis 2 also decreases, resulting in a distribution like G. Therefore, A
The distance measurement area that can be used without being affected by the Kuraray of the F light beam is ■.

Exit pupil P. c, P, )c', the outer exit pupil Poc separates the luminous flux of UB2 and U
Since clarification occurs in the AI luminous flux, the illuminance on the element surface far from the optical axis Z decreases, resulting in a distribution G. Also, the inner injection [! Since poa' causes a curvature in the LA2 light flux and the LBI light flux, the illuminance on the element surface near the optical axis 2 also decreases, resulting in a distribution J. Therefore, the distance measurement area that can be used without being affected by the AF light flux is .

When using a photographic lens with exit pupils P, d, P, and d', large vignetting occurs in the light flux of UB2 and the light flux of UAI due to the outer exit @Pod, so the illuminance of the element surface far from the optical axis 2 becomes large. down, the distribution I (and therefore the ranging area I.

■ and ■ cannot be used, and the inner exit pupil P. d' causes clarification in the LA2 luminous flux and the LBI luminous flux, so the illuminance on the element surface near the optical axis 2 also decreases, resulting in a distribution J, and therefore, the ranging area ■ cannot be used either,
In the end, there is no usable ranging area.

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

(Leaving space below) Table 1 (Selection table of on-axis distance measurement area from exit pupil position and exit pupil outer diameter) In the above table, Pz: Exit pupil position P s: A F pupil position Po: Exit pupil outer diameter■ ~■: Distance measurement area ×: Distance measurement impossible Table 2 (selection table of on-axis ranging area from exit pupil position and exit pupil inner diameter) In the above table, Pz: Exit pupil position P s ,: A F pupil position Poo: Exit pupil inner diameter I~■: Distance measurement area ×: Distance measurement impossible Table 3 (Selection table of off-axis distance measurement area from exit pupil position and modified exit pupil outer diameter) In the above table, Pz: Exit pupil position P s: A F pupil position po: Deformed exit pupil outer diameter I~■: Distance measurement area In the table, Pz: Exit pupil position Ps: AF pupil position po': Modified exit pupil inner diameter ■~■: Distance measurement area An example of a distance measurement area selection table in an on-axis distance measurement frame is shown. In Table 1, 1. U, m, and N indicate distance measurement areas; * indicates that the illuminance distribution is too clear and distance measurement is impossible; *POI to P; 4, Pz, ~Pz are predetermined constants obtained from the above calculation formula. Injection MIP mentioned above
, t+ is P z = P s , P ob = Os
This applies to the case of Qs, and the exit pupil P. a is P Z 3 <P
z<Pz4. In the case of P, as< P oa< P 04, the exit pupil P6c is Pz+<Pz<Pzz, P or<
P6c (In the case of P 02, exit pupils p and d are Pz<Pzl
, Pod<Po+.

The selection of the distance measurement area for the non-reflective telephoto type can be made from this Table 1.

Further, Table 2 shows an example of a table for selecting a distance measurement area in an on-axis distance measurement frame from the exit pupil position Pz and the exit pupil inner diameter P0', and shows the above-mentioned exit pupil P. b゛ is Pz=Ps, P
This applies to the case where ob'=OsQs', and the exit pupil P oa'
is PZs<PZ<PZ<, Po)'<PoIL”<Po
*”, the injection @Poc' is PZI<PZ<PZ2.
When POI'<P6c''<P02', the exit pupils p and d' are Pz<, Pzl.

In the case of a zero-reflection telephoto type that corresponds to the case "P od'< P or", at a predetermined exit pupil position Pz, select the distance measurement area from the exit pupil outer diameter Po using Table 1, and A distance measurement area is selected from the inner diameter Po° 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 p0 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 partially related to the pupil position Pz.

P o = P o k ・ΔPo (o≦≦1) Here, in FIG. 6, the chief ray ip of the AF light flux
Assuming that the position where Pz intersects with the optical axis 2 is Pz = Ps (AF pupil position, constant), when Pz = Ps vicinity, =
o, which indicates that the AF light beam is not deviated from the main optical axis 2, and at the position where it is most likely to be clear, ΔP0
This shows that there is no influence of (see Figure 4), and that Pz<
When Ps or when Pz>PS, k approaches 1.

Generally, the AP 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 takes into consideration the margin between the AF beam area AFP of the focus detection optical system located off the optical axis and the exit pupil outer diameter P0 at the exit pupil position Pz, which is significantly different from the AP pupil position Ps. This is a coefficient for changing the weighting of ΔP when

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 be easy to understand.

■Also, for a photographic lens whose exit pupil position Pz is far away from the AF pupil position Ps, the AF 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 clarify.

Regarding the exit pupil inner diameter P0° for selecting the off-axis distance measurement area, the modified exit pupil inner diameter p0° is Po'=Po.

-I- is defined as '-Δpo' (o≦≦1), and the above-mentioned P.

A similar argument can be made by replacing p0゛ with p0゛. Table 4 is an example of a selection table for the distance measurement area in the axis-lateral pressure 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 6a, 16b, and 16c. (IFC) 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 transmits it to the microcontroller (COM) via the data bus (DBAF). and a function to transmit the completion of the charge accumulation operation of the CCD image sensor array to the interrupt input terminal (INT) of the microcomputer (COM). Note that the charge storage time in the C'CD image sensor array is controlled by the output of a light receiving section (not shown) that monitors the brightness of the subject.

(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 (9G) and (p+) of the microcomputer (COM>). (DPA)
is the output of the microcomputer (COM))・(+)2), (
This is a display unit for displaying the moving direction of the lens, focusing, and a warning that focus cannot be detected based on the signals from 9-).

(ENL) is an encoder that outputs pulses to monitor the lens drive behavior (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 output port < p, )'
When the level is “Low”, the AF encoder (ENL
), and when the level is "IIigbo", the pulse from the aperture encoder (ENAP) is sent to the event counter input terminal (CNTR). An event counter is provided inside the microcomputer (COM), data is preset in the event counter, and the terminal (CNTR)
The contents of the event counter are counted down every time a pulse is input to the , and when the contents of the event counter reach 0, an interrupt is generated.

(S,) is a photometry switch that is closed in the first step when the release button is pressed, and the closing signal of this photometry switch (Sl) is sent to the interrupt input terminal (INT, ) of the microcomputer (COM).
and input boat (pi)'\large input. (S2) is a release switch that is closed in the second step of pressing the release button, and the closing signal of this release switch (S2) is as follows:
It is input to the input boat (p6). (S3) is a reset switch that is closed when the exposure control operation is completed and opened when the winding/charging is completed, and the closing signal of this reset switch (S,) is input to the input port (p,). (aV) is a power supply circuit, which operates when the power supply control signal (pwc> output from the output port (p8) is at the “LOII+” level. This power supply circuit (GV) is connected to the power supply battery (BA). A high voltage (HV) and a low voltage (LV) are output based on the output.The high voltage (HV) is
DT) and interface circuit (IFC). In addition, the low voltage (LV) is the aforementioned display unit (DPA),
encoder (ENL), (ENAP), data selector (SEC), and film sensitivity reading circuit (IS), which will be described later.
D), lens circuit (LEC), photometry and A/D conversion circuit (MEC), decoder/driver (DDR) power supply, motor control circuit (MDA), (MDF>, display section (DSP) , the microcomputer (COM) receives power directly from the power battery (BA) via the power line (EV).

<l5D) 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, the microcomputer (
Fillnow sensitivity data is sent to the serial input terminal (SIN) in synchronization with the serial clock (sci<) from
) serially. (LEC) is a lens circuit provided in the interchangeable lens.
) has a circuit configuration disclosed in, for example, Japanese Unexamined Patent Publication No. 59-140408, and the output port (p+.

When the lens circuit selection signal (C8L) from ) becomes "Low" level, various data stored in r(OM) in the lens circuit (LEC) is serially inputted in synchronization with the serial clock (SCIO). Send serially to the terminal (SIN).Here, the lens circuit (LEC
) The data fixedly stored in the ROM will be explained separately for fixed focus lenses and zoom lenses.

(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=Avmax. For fixed focus lenses, address 04; for zoom lenses, address 10-IF is the focal length (
The data of f) is stored. In addition, in the case of a zoom lens, the lower 4 bits of 10 or more addresses are 0 to F.
is addressed by the signal obtained from the zoom encoder in response to zooming. address 05 or address 2
For 0 to 2F, the defocus amount is controlled by a lens drive motor (M
A coefficient (K) for converting into a driving amount of OA F ) is stored. At address 06 or addresses 30 to 3F, data on the amount of aperture change (ΔAv) due to zooming is stored, and in the case of a fixed focus lens, ΔAv=O. Address 07 or addresses 40 to 4F contain exit pupil value W (PZ) data, address 08 or address 50
~5F stores data on the exit pupil outer diameter (Pa). Address 09 stores data on the exit pupil inner diameter (po'), and for lenses other than reflective telephoto lenses, P
o'=O. address OA or address 6
External image height correction data ΔP0 is stored in addresses 0 to 6F, internal image height correction data ΔP0° is stored in address OB,
For lenses other than reflective telephoto lenses, the inner image height correction data ΔP0'=0.

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

(M B C) is a photometry and A/D conversion circuit, and when low voltage (LV) power supply from the power supply circuit (GV) is started, photometry operation is started and the output from the output port (p+2) is When the A/D conversion enable signal (ADEN) goes to "Low" level, A/D conversion is repeated at a constant cycle. Then, when the photometry and A/D conversion circuit selection signal (CSME) from the output port (p++) becomes “Low” level, the A/D converted and latched data is synchronized with the serial clock (SCK). and sent to the microcomputer (COM). (DDR) is a load driving circuit, which 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 (2CM), 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 description, the symbol "#" means a step number of the program. When the release button is operated, the photometry switch (SZ> is closed by pressing the first step, an interrupt signal is input to the interrupt input terminal (INTO), and the microcomputer (COM>) Including routine I N To
Start the operation from. First, the power supply control signal (PWC) output from the output port (pl) is set to "Low" level to operate the power supply circuit (GV) (#1),
Next, the interface circuit (I FC), display circuit (
Outputs the reference clock (CKOUT) to the DSP), photometry and A/D conversion circuit (MBC), and performs the COD initialization operation to flush out the charge accumulated in the CCD (#2゜#3) 0 Next, The charge accumulation operation of COD is started, and when the charge accumulation operation is finished, the interrupt input terminal (I-N
T+) is enabled to accept interrupt signals to the output port (pI2
) from A/D conversion enable signal (ADEN) to “Low”
level, and A/D converts the photometric value (#4° #5.
#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,
Determine the status of flags IFF, IFF2. IF
F 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 goldfish, the flag IFF is set to 1, and the calculation routine is started. Transition. Also, the flag I F
If F + and I F F t are both 1, the process directly proceeds to the calculation routine without inputting photometric data (#9 to #13).

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 (Avo=A
If it is a reflective telephoto lens, A vo = A vmax, so #16, A vo *
If it is A vmax, it is a normal interchangeable lens, so move on to step #19. First, if the lens is not attached,
When a reflective telephoto lens is attached, it is of course impossible to control the aperture, and the aperture must be considered fixed.

Therefore, in step #16, (photometric data) = Bv
The exposure time Tv is calculated by adding the ISO value Sv indicating the film sensitivity to -Av (Bv is the subject brightness, Av is the 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 a warning display (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 =
The maximum aperture value Av+*ax) is displayed in step #21. If it is determined in step #15 that it is not a reflective telephoto lens, (photometry data) = B in step #19.
Calculate the exposure value Ev by adding Avo+ΔAv+Sv to v−(Avo+ΔAv).1. By performing a program exposure calculation (#20) based on this exposure value Ev, the aperture value Av and exposure time Tv are calculated and 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 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. This step is provided to proceed from this step to the AF 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 is calculated from the photometry data after focusing. If so, the process moves to an exposure routine and performs exposure control operations.

On the other hand, if the conditions are not met, it is determined whether the photometry switch (Sl) is closed in step #251, and if it is closed, the process returns to the photometry routine, and if it is not closed, the stop routine is executed. perform the following actions.

In the stop routine, first, all flags are reset, the output port (p4) is set to "Low" level, data is sent to the display circuit (DSP) to set the display to 0FF (no display state), and the motor (M OAF), the output of the reference clock (CKOUT) is stopped, the power supply circuit (GV) is inactive, and the signal (ADEN) is stopped.
is set to "High" level to disable A/D conversion, and the microcomputer (COM) stops operating (#26 to #32).

Next, the operation of the AF routine will be explained using FIG. 11. When the CCD storage operation is completed, an interrupt input signal is input from the interface circuit (IFC) to the interrupt input terminal (INTI), and the operation starts from #39.
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 COD output from the interface circuit (IFC) are sequentially A/D converted and taken into the microcontroller (COM), and the flag CF is set to 1, and the flag AEF is set to 1. It is determined whether the flag AEF is set, and if the flag AEF is O, the first photometry routine and calculation routine have not finished, so the execution step when the return address (INT) is interrupted. ) Return to 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 AF routine immediately after the capture of CCD data is completed.

In the AF routine, first set the flag CF to 0,
The process moves to subroutine 5UB1 shown in FIG. 13. In this subroutine 5UB1, the exit pupil position 'ffl P z
#4 Selects a distance measurement area where focus detection is possible in the on-axis distance measurement frame A based on the exit pupil outer diameter P0 and
In step 4, the modified exit pupil outer diameter P for the off-axis ranging frames B and C is determined from the exit pupil outer diameter P0 from the lens, the external image height correction data ΔP0, and the constant k of the camera body. Then, the process moves to subroutine 5UB2 shown in FIG. Selecting the Distance Area Next, in step #45, it is determined whether the exit pupil inner diameter P o'' is O. If P o' = 0, it is a normal lens, and the process immediately proceeds to step #47. On the other hand, if P , +≠0, it is a reflective telephoto lens,
The process moves to subroutine 5UB3 shown in FIG. 15. In subroutine 5UB3, a distance measurement area in which the focus can be detected is selected from the on-axis 14 distance frame A based on the exit pupil position Pz data and the exit pupil inner diameter Po' data, and the distance measurement area that is selected in subroutine 5UB1 is selected. Moreover, in this subroutine 5UB3, the exit pupil inner diameter P0° from the lens, the internal image height correction data ΔPo', and the camera body's Next, the process moves to subroutine 5UB4 shown in FIG. 16, and the off-axis ranging frames B and C are calculated from the exit pupil position Pz and the modified exit pupil inner diameter p0°. A detectable ranging area is selected, and the ranging area selected in subroutine 5UB2 and also selected in subroutine 5UB4 is finally determined.

In step #47, data Pz, P regarding exit pupils are
0. Based on Po', r5o, and Po', 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, 1
If there is a distance measurement area selected at any time, perform focus detection (defocus amount detection) for each selected distance measurement area (#48), and provide reliable data for each distance measurement area. Determine whether data is obtained, and if all data is unreliable, move to step #51 (
In steps #49, #50) and #51, the flag lFF
Set 2 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, the COD accumulation operation is started, and the interrupt by INT is enabled, and the process returns to the return address in the photometry routine and calculation routine.

If it is determined in step #50 that at least 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 focus area, and if it is outside the goldfish area, the process moves to step #62, and if it is within the focus area, the process moves 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 (M OA F ) #63
), preset this drive amount in the event counter (EVC) (#64), enable event counter interruption #65), and set the lens drive motor (MO
A F ) is operated (#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 signal is input to the event counter from the terminal (CNTR) via the terminal (CNTR), and the contents of the event counter are decremented.

When the content of the event counter reaches 0, an interrupt (EVC interrupt) is generated by the event counter, #1 in Figure 12.
Perform the operation from step 00.

In step #100, it is determined whether AF is in operation or not. In this case, AP is in operation, so the process moves to step #101, the motor (MOA F ) is stopped, and focus detection is performed for confirmation. Specifically, after starting the COD accumulation operation (#102) and enabling interrupts from the interrupt input terminal INT (#103), the process moves to the photometry routine 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 in-focus state 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
2) is closed and the flag lFF2 is set to 1 in step #25, the process moves to the exposure control routine shown in FIG. 12. First, set the AF 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 or not 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. Determine whether the control aperture value (Av>) is equal to the open aperture value (Avo), and calculate A v = A
If it is vo, the process similarly moves to step #83.

On the other hand, if A v * A vo, the number of refinement stages (A
Set y-Avo) to the event counter (EVC) and set the port (p,) to the "High" level so that the pulse from the encoder (ENAP) that monitors the aperture amount is output from the selector (SEC). protect(#
80, #81, #82), and #83, #84
Wait for a certain amount of time at step . During this time, if a narrowing operation is performed and an event counter interrupt occurs, #104
In step , the aperture magnet (APM) is operated to stop the aperture. Then, after a certain amount of time has passed,
The reflection mirror has been raised and the front curtain magnet (I
CM) to start running the first curtain and count the exposure time (#85, #86). When the count is finished, operate the second curtain magnet (2CM) and start running the second curtain. (#87), and then wait for the trailing curtain to complete running and turn on the reset switch (S,) (#88), and then turn on the reset switch (S3).
When this happens, the charging motor (MOCH) is operated to wind the film and charge the exposure control mechanism, and wait until this operation is completed and the reset switch (S3) is turned OFF (#89).

#90), and the reset switch (S, ) is OFF.
, wait until the release button is released and the metering switch (S, ) turns OFF (#91). When the metering switch (Sl) turns OFF, it performs the stop routine operation and then starts metering. Operation is stopped until the switch (Sl) is turned on and the microcomputer (COM) is activated.

Subroutine SUB1.5UB2 shown in FIG.
The specific contents of 5UB3 and 5UB4 are shown in Figures 13 and 14.
In the subroutine 5UB1 of FIG. 13 shown in FIGS. 15, 15, and 16, the exit pupil position P
A distance measurement area is selected from the on-axis distance measurement frame A based on z and the exit pupil outer diameter P0. First, in step #110, P
Determine o < P o +, P o < P o
In the case of +, there is no detectable ranging frame and #12
Move to step 8.

On the other hand, P0≧P0. Then, in step #111, determine Po<Pot, and if Poz>Po≧PoI,
In step #112, Y is set as the address.

Similarly, in step #113, P ox > P
If 0≧poz, set Y, 2 as the address in step #114, and set PO4>PO≧P in step #115.
If it is O3, set YI3 as the address in step #116, and set P in step #115. If ≧P04, #
In step 117, 7 units are set as addresses.

Next, the exit pupil position Pz is also determined in the same manner according to Table 1, and if Pz≧PZ4 in step #118, the process moves to step #128, and in step #118, Pz, )pz If ≧Pz, set the Xth address in step #120, and set Pz in step #121.
If s>P z≧PZ2, x in step #122
5. Set the address to PZ in step #123.
If 2>Pz≧Pz, set X+Z as the address in step #124, and set P in step #123.
If ZI > P z, then XIl in step #125
Set to address. As a result, the position in Table 1 can be set using address data (X, 1st, Yth), and this address data (X IIrY) specifies the ROM table in which Table 1 is stored. death,
The data of the focus detection area stored therein is set in the register ERAR. This data is 4-bit data that corresponds to distance measurement areas ■ to ■.
The bit corresponding to the distance measurement area where the focus can be detected is 1, and the bit corresponding to the distance measurement area where the focus cannot be detected is 0. Therefore, for example, address data (X11.Y
ll) is specified, "0001" or "'0011" is specified.
” data, address data (X14.Yl,) is specified, “0001” or “1001” data is specified, address data (XIl, Yl4) is specified, “1”
111" is set in the register ERAR. Also, in step #128, since there is no distance measurement area where focus can be detected, the register ERAR is set to "000.
0'' is set.

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 Pz and the modified exit pupil outer diameter p0 according to Table 3. . Subroutine 5UB1 in Figure 13
Similarly, in step #130, P o <f' o
+ or in step #138 Pz≧P24
In this case, there is no distance measurement area where the focus can be detected, so "0000" is set in the register ERBCH. Furthermore, #1
If p01≦P o < P o z in step #31, set Y21 as the address in step #132,
At step #133, p02≦P o <f' On
If so, set Yl2 as the address in step #134, and set po, ≦P o < in step #1'35.
If P O4, 'Yzs is set as the address in step #136, po is set in step #135, and if ≦p0, Y2 is set as the address in step #137. Furthermore, in step #139, Pz, ≦PZ<PZ4
If so, set X24 as the address in step #140, Pz in step #141, if ≦Pz<Pz, set X23 as the address in step #142,
In step 143, if Pz+≦Pz<Pz, then #1
Set X22 as the address in step 44 and #143
If P ZI > P z in step #145, set X21 as the address. Then, the ROM table is designated by the set address (X211Y21), and the data stored at that address is set in the register ERBCR.

In the subroutine 5UB3 shown in FIG. 15, a focus detection area is selected in the on-axis distance measurement frame A from the exit pupil position Pz and the exit pupil inner diameter P0° according to Table 2, and finally, , a distance measurement area in which the focus can be detected is selected using the on-axis distance measurement frame A determined from both the exit pupil outer diameter Po and the exit pupil inner diameter P0'. First, according to Table 2, address data (X3+, Yst,) is set (#
151 to #166), and this address data (
Specify the ROM table with
The logical AND with the data set in is performed for each bit, and the 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 O, that bit becomes O,
Exit pupil outer diameter P. , and the exit pupil inner diameter P0'' are set in the register ERAR.

Note that p, l≧P0.゛or when Pz<Pz+, there is no ranging area where the focus can be detected, so the register ER
“0000” is set in AR.

In subroutine 5UB4 in FIG. 16, a focus detection area is selected from off-axis distance measurement frames B and C based on the exit pupil position Pz and the modified exit pupil inner diameter p0° according to Table 4, Finally, a distance measurement area in which the focus can be detected using the off-axis distance measurement frames B and C is selected from both the modified exit pupil outer diameter p0 and the modified exit pupil inner diameter p0°. First, similarly to subroutines 5UB1 to 5UB3 in FIGS. 13 to 15, address data (X 41 , Y at >
oo, set according to the size of Pz, specify the ROM table with this address data (X41.Y41>, read the data stored at this address, and
This data and the register ER have already been entered in subroutine 5UB2.
By performing an AND with the data set in BCR for each bit and setting this result in register ERBCR, the distance measurement area where the focus can be detected is finally set.
Note that p0゛≧p0. °, there is no distance measurement area where focus can be detected, so the register ERBCH contains "o o
o o'' is set.

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.
Furthermore, 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.

In addition, the focus detection system for a reflective telephoto lens in this embodiment determines whether focus detection is possible for a plurality of focus detection areas based on data regarding the exit pupil outer diameter, exit pupil inner diameter, and exit pupil position. Although each is determined, there may be only one focus detection area, and it may be configured to determine whether or not focus detection is possible for this one focus detection area.

Furthermore, the reflective telephoto lens in this example stores data regarding the exit pupil outer diameter, exit pupil inner diameter, and exit pupil position in order to determine whether focus detection is possible. The configuration may also be configured to output data indicating whether or not the lens is compatible. In this way, a camera with a conventional focus detection function can output information regarding the exit pupil outer diameter, exit pupil inner diameter, and exit pupil position. It is also possible to support systems that do not require a function to determine whether or not focus detection is possible based on data.

(Effects of the Invention) In the focus detection system for a reflective telephoto lens according to the present invention, focus detection is performed based on data regarding the exit pupil outer diameter, exit pupil inner diameter, and exit pupil position from the reflective telephoto lens. It is determined whether or not the means is capable of optically accurate focus detection, and if focus detection is possible, the focus detection means is operated, so whether or not focus detection is possible even when using a reflective telephoto lens. Therefore, it is possible to realize an inexpensive and compact focus detection system using a reflective telephoto lens.

In addition, in the reflective telephoto lens according to the merged invention, data regarding the exit pupil outer diameter, exit pupil inner diameter, and exit pupil position that are unique to the lens are fixedly stored, and these data are read based on the read signal from the body. Since the reflective telephoto lens is sent to the body, it is possible to correctly determine whether or not there is vignetting of the light beam due to the exit pupil of the reflective telephoto lens in a body equipped with this reflective telephoto lens. This has the effect of being able to determine whether focus detection is possible.

[Brief explanation of drawings]

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 reflective telephoto lens used. FIG. 5 is an explanatory diagram of the pupil rWi constant of the focus detection optical system used in the same. FIG. Figure 7 is an explanatory diagram of the axial focus detection optical system used in the above, Figure 8 is a diagram showing the illuminance distribution on the CCD image sensor array used in the above, and Figure 9 is an illustration of a camera system using the focus detection system in the same as the above. circuit diagram,
10 to 16 are flowcharts for explaining the operation of the same. 1- is an optical means, 25 and 22 are 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 reading signal input means, 8 is a data sending means, ML is It is a reflective telephoto lens.

Claims (2)

[Claims] (1) an optical means for forming at least one pair of light images from light beams from at least one pair of different regions on the exit pupil plane of a reflective telephoto lens; at least one pair of light receiving means for receiving the light images; at least one focus detection means that performs focus detection by detecting relative displacement of the optical image based on the outputs of the paired light receiving means; an exit pupil outer diameter read from the reflective telephoto lens; and an exit pupil inner diameter; A determination means for determining whether the focus detection means can perform optically accurate focus detection from a combination of the optical means and the optical system of the reflective telephoto lens, based on data regarding the exit pupil position; A focus detection system for a reflective telephoto lens, comprising means for operating a focus detection means, if any. (2) A reflective telephoto lens attached to a camera body having focus detection means, comprising a memory means for fixedly storing data specific to the lens, a means for inputting a read signal from the camera body, and a read signal. means for sequentially transmitting the data stored in the storage means to the camera body based on A reflective telephoto lens characterized in that it includes data regarding its position.