JPS63236018A - Focusing information output device for camera - Google Patents

Abstract

PURPOSE:To simply and with high accuracy derive a relation of an object and depth information of a photographic lens, in a finder visual field, by providing a depth of field arithmetic means, a distance measurement arithmetic means, and an indepth of field deciding means. CONSTITUTION:The titled device is provided with a depth of field arithmetic means 6 for operating depth of field information, based on absolute distance information, set diaphragm value information and a lens intrinsic data, a distance measurement arithmetic means 7 for outputting the shift quantity of a focused point of an object image which has passed through a photographic lens and a focused point of the photographic lens, as a distance measurement arithmetic value, and an indepth of field deciding means 8 for deciding whether the focused point of the object image exists in the focus side depth of the focused point of the photographic lens or not, based on the depth of field information and the distance measurement arithmetic value,and from the indepth of field deciding means 8, focusing information such as whether the object exists in the depth or not, or the front focus or the rear focus, etc. is outputted. In such a way, after the device has been set to a focus lock state, in case other object has been led into a focus zone, whether it new object exists in the focused depth of that time or not can be brought to an image display in a finder with high accuracy.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a camera 99 focusing information output device, more specifically,
The present invention relates to a focusing information output device for a camera that displays depth of field information for AF (autofocus) driving within the viewfinder field of the camera.

[Prior Art] Conventionally, depth of focus information has been displayed by adding a depth of focus scale to a distance scale on a distance ring of a lens barrel. By comparing the distance scale on the distance ring of the lens with the depth of focus scale corresponding to the set aperture value, it is possible to know the range of absolute distances that can be considered to be in focus. Further, in a negative-eye reflex camera, by narrowing down the aperture diameter to a set aperture diameter through a preview operation, it is possible to check the in-focus state of the image in the finder.

[Problems to be Solved by the Invention] By the way, when confirming the depth using the distance scale on the distance ring of the lens barrel and the depth of focus scale, it is impossible to determine whether or not the depth is within the depth range unless the distance to the subject is known. Furthermore, since this display scale is generally located outside the camera or lens barrel, it is extremely troublesome to check the depth of field display scale while looking through the finder.

In addition, the method of checking the depth of field by previewing a negative-eye reflex camera is very intuitive because it is done visually, and it is done by stopping down to the set aperture value, so the depth of field is not visible in the viewfinder. The image was dark and it was difficult to see the subject. Therefore, even with the above-mentioned methods, the shutter opportunity may be missed due to the confirmation.

Therefore, the present invention has been made with attention to the above-mentioned points, and is a method of focusing an automatic focusing camera (hereinafter abbreviated as AF left camera) on a certain subject and prohibiting further lens driving. If you introduce another subject into the focus zone after entering the so-called focus lock (AF lock) state, you can easily and accurately visualize in the viewfinder whether the new subject is within the current depth of focus. The purpose of the present invention is to provide a camera focus information output device that can display the information.

[Means and effects for solving the problem] The camera focusing information output device according to the present invention is shown in FIG. 1 showing its concept. Information output means 2 and the photographic lens 1
a set aperture value output means 3 for reading out set aperture value information;
A lens-specific data storage means 4 for storing lens data specific to the photographing lens l; a field for calculating depth-of-field information based on the absolute distance information, the set aperture value information, and the lens-specific data; a depth calculation means 6; a distance calculation means 7 that outputs the amount of deviation between the in-focus point of the photographing lens 1 and the film surface as a distance calculation value; and the depth of field information and the distance calculation value. Based on the depth of field determination means 8, the depth of field determination means 8 determines whether the subject is within the depth of field or whether the subject is in front of the focal point. , focus information such as whether the camera is in rear focus or not is output.

[Embodiment] Hereinafter, the present invention will be described as a camera having an autofocus (hereinafter abbreviated as AF) function and an interchangeable lens.
An embodiment applied to a camera having an absolute distance information output means disclosed in Japanese Patent No. 275251 will be described.

FIG. 2 is an overall block diagram mainly showing the power supply of the camera system to which the present invention is applied. Power battery 1
1 voltage V. 0 is DC/D when the power switch 12 is opened.
The voltage is boosted by the C converter 13 and the line ρ. , 91 is constant voltage vDD. Line Uo,,C
Main CPU 14 between I and bipolar circuit 15. Bipolar circuit 16, strobe control circuit 17. A lens specific data circuit 18a, a lens fixed data circuit 18b, and a data back circuit 19 are connected, and the power supply control of the bipolar circuit 15 is performed by a signal from the power control circuit of the main CPU.
Power supply control of the data pack circuit 19 is performed by a power control signal from the bipolar circuit 15.

Focus sensor 20. A/D converter 21. AF CPU
The AF block consisting of 22 is a power supply control transistor 2
3 through the line ρ. 9g1, and power supply control for this AF block is controlled by the main CPU 14.
This is done by controlling the transistor 23 on and off using a signal from the AF power control circuit.

The AF CPU 22 is a circuit for performing AF algorithm calculations, and is connected to an AF display circuit 24 that displays in-focus/out-of-focus status. The main CPU 14 is a circuit for controlling sequences of the entire camera such as winding, rewinding, and exposure sequences, and is connected to a display circuit 25 for displaying other than the above-mentioned focus display. Bipolar ■Circuit 1
Reference numeral 5 denotes a circuit including various drivers necessary for camera sequences such as winding and rewinding motor control, lens drive, and shutter control, and is connected to an AF motor drive circuit 26, an AP auxiliary light circuit 27, and the like. The bipolar 1 circuit 16 is a circuit mainly responsible for photometry, and has a photometry element 28. The strobe control circuit 17 is for controlling the light emission of a built-in or external strobe 29. The lens-specific data circuit 18a is a circuit that stores unique lens data necessary for AP, photometry, and other camera control, which differs for each interchangeable lens. Among the lens data contained in this lens-specific data circuit 18a, the data necessary for the AP includes a lens magnification coefficient (zoom coefficient), a macro identification signal, and absolute distance coefficients a and b.
, power focus duty coefficient.

AF accuracy threshold ETh, lens movement direction.

This is the open F value, etc. The lens fixed data circuit L8b is a circuit that stores fixed data necessary for calculation that does not differ for each interchangeable lens. Also, the lens specific data circuit 18
a. The data of the lens fixed data circuit 18b may be stored in the memory of the main CPU 14 or AF CPU 22 in the camera, respectively.

The bipolar ■circuit 15 monitors the state of the power supply voltage VDD, and when the power supply voltage drops below the specified voltage, it sends a system reset signal to the main CPU 14, and supplies power to the bipolar ■circuit 15 to data pack circuit 19, and Focus sensor 20° A/D converter 21 and A
The power supply to the AP block consisting of the P CPU 22 is cut off. Power is supplied to the main CPU 14 even if the voltage is below the specified voltage.

FIG. 3 is a system diagram showing the transmission and reception of signals centered around the AF block. The AF CPU 22 and the main CPU 14 transmit and receive data through a serial communication line, and the direction of the communication is controlled by a serial control line. The content of this communication is
These are unique lens data in the lens unique data circuit 18a and absolute distance information. In addition, from the main CPU 14
The camera mode (AF single mode/AF sequence mode/power focus (hereinafter referred to as P
(abbreviated as F) mode/other mode) information is decoded through the model line. Furthermore, main C
AFENA from PU14 to AF CPU22 (AF
The AF enable) signal is a signal that controls the start and stop of each mode of AP and PF.
An EOFAF (end of AF) signal sent from the PU 22 to the main CPU 14 is a signal that is issued at the end of the operation in the AF or PF mode, and is a signal that permits transition to the exposure sequence.

In addition, the bipolar circuit 15 decodes the AF motor control line signal from the AF CPU 22, and
Drives the F motor drive circuit 26. The AF motor (lens drive motor) is driven by the output of the AF motor drive circuit 26.
31 rotates, the slits 32 provided at equal intervals in the rotating member of the lens barrel rotate, and a photointerrupter 33 is formed in which a light emitting part 33a and a light receiving part 33b are arranged facing each other across the path of the slits 32. Count the slits 32. That is, the slit 32 and the photo interrupter 33
constitutes the lens movement amount detection section 34, and the address signal (count signal of the slit 32) issued from the movement amount detection section 34 is waveform-shaped and taken into the AF CPU 22.

The sub-lamp (hereinafter abbreviated as S-lamp) signal sent from the AFCPU 22 to the bipolar ■ circuit 15 is a signal that controls the AF auxiliary light circuit 27, and when the subject is low light (low brightness) and low contrast, the S-lamp 27 is sent to the bipolar circuit 15.
Turn on a.

The AP display circuit 24 connected to the AF CPU 22 includes a focus display LED (light emitting diode) 2 that lights up when in focus.
4a and an LED 2 for displaying failure to focus, which lights up when it is impossible to focus.
4b. Note that this AF CPU 22 includes a clock oscillator 35. A reset capacitor 36 is connected.

Further, the AF CPU 22 and the A/D converter 21 exchange data via a pass line, and the direction of the data transmission is controlled by a pass line control signal. Then, A/D from the AF CPU 22: ] > Bar
A sensor switching signal and a system clock signal are sent to the controller 21. And A/D converter 21
For example, for the focus sensor 20 consisting of a CCD, the CCD
Sends a drive clock signal and a CCD control signal, reads the CCD output from the focus sensor 20, converts the read analog value CCD output into digital, and sends it to the AF CPU 2.
Send to 2.

Next, a flowchart of the program operation of the microcomputer centering on the AF block shown in FIG. 3 of the camera having the focus information output device of the present invention will be explained. The AP block is the main CP block, as shown in Figure 2.
By activating the AF power control circuit U14, the transistor 23 is turned on and the power supply voltage ■
DD is supplied, thereby beginning execution of the power-on reset routine shown in FIG.

When this power-on reset routine is started, the AF block drive circuit is initialized in the <I10 initialization> subroutine. Specifically, the AF display circuit 24, the AF motor drive circuit 26, the AF auxiliary light circuit 11=27, etc. are turned off, and the serial communication line with the main CPU 14 is initialized.

Next, in the subroutine of "mode read", the main C
After reading the model line signal (mode signal) from the PU 14 and determining what lens drive mode to execute, a certain period of time passes through the ``timer'' routine, and then the mode is read through the ``mode read'' routine again. Reading the switching point. Then, the process returns to the first mode (mode 0 read) until the mode switching is completed. <mode·
The reason why the read> subroutine is passed through twice with the timer in between is to prevent reading errors at the time of mode switching.

When the mode has been reliably switched and the mode before and after the switch is the same, the mode after the switch is read and a transition is made to the subroutine for each mode. That is, the lens drive modes include lens reset>, <
PF (power focus)>, <AFS IN (A
There are the following modes: <I10 Initialize> and <AFSEQ (AF Sequence)>. When one of these modes is selected, the subroutine of the selected mode is executed, and then the above <I10 Initialize> routine is executed. Return to

Lens Reset>, <PF>, <AFSIN>.

When none of the <AFSEQ> modes are selected and the <Other> mode is selected, this is treated as mere noise, and after a certain period of time has elapsed in the <Timer> routine, the above <110 Initialize> is performed. Return to

Here, the operation of the lens reset mode is to forcibly retract the lens to the infinity (-) position, thereby changing the relative distance signal, that is, the distance measurement output signal output from the focusing sensor 20. This is an initialization operation for converting the number of pulses from the infinite distance (bell) position into an absolute distance signal, that is, an operation to clear the absolute distance counter. If <Lens Reset> is selected,
After this absolute distance counter is cleared, the I10 initialization operation is returned to, for example, after 5 ms has elapsed. Also, <P
In the F> mode, the distance ring of the lens is driven not manually but by the lens drive motor 31, and the focusing operation of the lens is performed using manual focusing or focus aid. More specifically, the PFUP (up) operation switch SW1 and the PFDN (down) operation switch SW2, which will be described later, are turned on.

When the lens is turned off, the lens is extended and retracted. Furthermore, the operation in the <AFS IN> mode is a one-shot AF operation, and the focus is locked after the AF operation for the subject. Furthermore, <A
The FSEQ> mode is continuous AF, and in this mode, the AF operation will be performed continuously as long as the first stage of the release button continues to be operated.

By the way, as operation switches for each mode of lens drive, four operation switches SW to SW4 are used, as shown in Table 1 below.

■ Table 1 (*Can be either ON or OFF) 1. as shown in Table 1 above. Second operation switch SW1. S
W2 is commonly used in the AP mode and the PF mode, and when the third operation switch 8W3 is off, the AF mode is selected, and when it is on, the PF mode is selected. 1st in AF mode. Second operation switch SWt, SW2
When both are off, the lens reset mode is set, when both are on, the AFSEQ mode is set, and when the first operation switch SWl is off and the second operation switch SW2 is on, the AFSIN mode is set. 1st and 2nd in PF mode
When the operation switches swl and sw2 are both off or on, the lens is in stop mode, and when the first operation switch SW1 is on, the motor rotates the distance ring toward the short distance side and extends the lens. The mode becomes PFUP (up) mode, and when the second operation switch SW2 is on, the mode becomes PFDN (down) mode in which the distance ring is rotated toward the long distance side and the lens is retracted. Further, the fourth operation switch SW4 is in either the on or off state in any of the AF modes, and is in the on or off state in the stop mode of the PF mode. There is no change in Hl (
When the lens drive motor 31 is turned off, the mode is set to LO (low speed) mode, and the motor 31 (see Figure 3) rotates at a low speed to make fine movements of the distance ring. It will be done.

Next, the operation of each lens drive mode will be explained using the flowcharts of FIGS. 5 and 6.

First, when the <AFSIN> mode is selected, the <AFSIN> routine shown in FIG. 5 is executed, and it is detected whether the AFENA signal from the main CPU 14 is at the "H" level (active). do. With the first operation of the release button, the AFENA signal becomes active, AF operation is started, and the <AFSIN2> subroutine is called. However, the second operation of the release button is accepted when the AF operation is completed, a focused state is obtained, and the exposure sequence is started. <AF
SIN2>, as described later, the C of the focus sensor 20
CD integration, distance measurement output calculation, lens driving, etc. are performed. Then, the focus is the result of the AF operation of this <AFSIN2>.

Out of focus is displayed by monitoring the AP status flag after the <AFSIN2> operation. The AF status flags include a low contrast flag (a flag that is set to "1" when the subject is in low contrast, hereinafter abbreviated as the LC flag), and a movement flag (when the subject is moving).
1 (hereinafter abbreviated as the M flag) and the closest flag (the flag that is set to "1" when the lens is about to be extended to the closest flag).
(hereinafter abbreviated as N flag), and when any of these flags is "0", focusing is possible.
If any of the above flags is set, it is impossible to focus, so as a result of monitoring the AF status flag, the same AF
If the status flag is "θ", the LED 24a of the AF display circuit 24 indicates that the focus is OK, and the A
If the F status flag is not "0", the LED 24b indicates that focusing is not possible. If the focus is not in focus, the process waits until the AFENA signal goes to "L" level, and returns when it goes to "L" level. If the camera is in focus, an EOFAF signal is issued, the AP operation is completed, and the main CPU 4 enters a state where it waits for the second step of the release button to operate, that is, to start the exposure sequence. And after this, CALPD>, <AFL>, <CALPDCK
After the routines > are executed in sequence, the AFENA signal is checked again. That is, once focusing is completed, even if the AFENA signal is active, subsequent lens operation is prohibited and the focus display LED 24a remains lit, resulting in a focus lock state. The AFENA signal from the main CPU 14 is at “L” level (
When the power-on reset flow becomes inactive), the process returns to the initial operation of the power-on reset flow shown in FIG.

While operating in the above <AFSIN> mode, <AFSIN2>
The program operation of the subroutine > is performed as shown in FIG. First, the RETRY flag is set to compare the previous 7fllJ distance fjr calculation value (previous output pulse of the focus sensor 20) and the current distance calculation value (current output pulse of the focus sensor 20). It is cleared, and the maximum number of distance measurements in a series of AF operations is set in the AF loop counter. After this, the maximum value of the CCD integration time is set in the ITIME register so that COD integration is reliably performed at a certain brightness or higher. Then, the AF status flag is cleared, and the S lamp flag is also cleared. The operations in the flow up to this point complete the initialization operation before starting the AP.

After this, the <lens read> routine is called, and after reading out each data in the lens contained in the lens specific data circuit 18a, <AF> for distance measurement is called.
> routine is called.

In this <AF> subroutine, S
It is determined whether or not it is necessary to light the lamp 27a. If it is necessary to light the lamp 27a, the S lamp flag is set, and if it is not necessary, it is cleared. Further, the low light flag (a flag set to 1'' when the subject is low light, hereinafter abbreviated as LL flag) and the LC flag are set to Cerato or cleared.

Now, after the distance measuring operation of <AF>, if both the LL flag and the LC flag are cleared, the routine of <pulse> is called and the lens drive amount is calculated.

That is, in the <Pulse> routine, in order to convert the AP (distance measurement) calculation output value obtained in the <AF> operation to the distance movement amount for each interchangeable lens, the lens-specific data circuit 18a sends a variable magnification signal. Information such as coefficients is read, and the number of pulses (address signals) corresponding to the amount of movement to the in-focus point is calculated based on the read magnification coefficient and the AF calculation output value.

After that, the AF calculation output value (ERROR) is compared with the AP accuracy threshold ETh read from the lens specific data circuit 18a, and the AF calculation output value (ERROR) is compared with the AP accuracy threshold ETh read from the lens specific data circuit 18a.
If ROR) is larger than the AF accuracy threshold ETh, the process proceeds to (2) and the RETRY flag is determined. 1
In the second AF operation, since the RETRY flag is θ'', the above drive pulse number is saved after the RETRY flag is set.Then, in the second and subsequent AF operations, the RETRY flag is set. Therefore, the current number of driving pulses is compared with the previous number of driving pulses.At this time, if the current number of pulses is smaller during the movement than the previous number of pulses, the lens drive will bring the focus Since this means that the next lens drive will be even closer, the current pulse will be saved in place of the previous pulse, and <M
DRIVAF> routine is called to drive the lens.

The purpose of comparing the previous pulse and the current pulse is to
The purpose is to prevent the divergence of the entire sequence. Possible ways to compare the two are (current pulse number):(previous pulse number X O,5), or (current pulse number)=(previous pulse number X 1.5). When the AF sequence system is likely to be in a divergent state, it is possible to perform AP operation while the subject is moving.
Immediately stop the lens drive, set the -22=M flag to prevent unnecessary AF operations, and proceed to ■<5DISCN, which will be described later.
T>, calls the routine <CALD I ST>.

After the lens is driven by <MDRIVAF>, 1 is subtracted from the distance measurement value of the AF operation set in the AF small loop counter. As a result, if the value of the AF small loop counter is not 0, the ITIM
Set the integration time in the E register, and then set the AFENA
When the signal is active (that is, the first operation of the release button is on), for the next AF operation,
Return to 0. In this way, each time the AF operation between O and 0 is repeated, the value of the AF small loop counter is decremented once, and the in-focus point is gradually approached, but the value of the AF small loop counter becomes 0. Even if the AP calculation output value (ERROR) is above the AP accuracy threshold ET
If it does not become smaller than h, it is assumed that it is impossible to focus and M
A flag will be set.

As a result of the AF operation between 0 and 0, if ERROR<ETh, that is, if the AF calculation output value (ERROR) falls within the focus error range, the AF status flag is cleared to indicate that the in-focus state has been reached. , <5DISCNT
>, calls the <CALDI ST> routine.

Here, after the <AF> operation described above, if the LL flag or LC flag is set, the state of the S lamp flag is tested. At this time, if the S lamp flag had been set to "1" in advance, the low light and low contrast state would have occurred even though the S lamp 27a was lit during the integral operation for AP. Therefore, in this case, the LC flag is tested again, and in the case of low contrast, the only lens NF (unable to focus) routine is called to actively display the inability to focus. That is, in this lens NF> routine, the lens is first extended to the closest position, and then moved to infinity (oo).
The user is actively notified of the inability to focus by moving the lens significantly. Note that the lens operation indicating inability to focus may be an operation of moving the lens from the infinity (cX3) position to the closest position. In addition, this <lens NF> uses an absolute distance counter to save the number of drive pulses (number of movement address signals) from the infinity (flash) position of the lens distance ring by hitting the infinity (Oo) position. is initialized. if,
If the contrast is not low, it means that the AF calculation was performed even though the light was low, so in this case,
Return to 0.

Also, if the S lamp flag was cleared in advance, it means that the S lamp 27a was previously off, so if the LL flag or LC flag is set, set the S lamp flag. , proceed to [F].

Therefore, the S lamp 27a will be lit in the second and subsequent AF operations.

In any case, at the end of <AFSIN2> operation, <S
After the routine DI 5CNT> is called and executed, <CALDI ST> is called. <SD
In the routine I5CNT>, the number of drive pulses from the infinite distance (■) position of the distance ring is set in the absolute distance counter. Then, in the <CALDIST> routine, the number of pulses set in the above absolute distance counter,
The absolute distance to the subject is calculated from the absolute distance coefficients a and b in the lens specific data circuit 18a, and the obtained absolute distance and the contents of the absolute distance counter are used as the main CP.
Sent to U14. After <CALD I ST> is executed, < in the flow of <AFSIN> shown in Figure 5.
Return to the position after the operation of AFSIN2>.

In addition, in the <AFSIN> flow shown in FIG. 5, <CALPD>, <AFL>, <CALP
DCK>(7)/l/-Let me explain. These routines are sequentially repeated while the AFENA signal is at "H" level (active).

First, in the <CALPD> routine, set aperture value information is read from the set aperture value output means 3, and this set aperture value information, lens specific data of the lens specific data circuit 18a, and lens fixed data of the lens fixed data circuit 18b are read out. Then, depth of field information is calculated from the contents of the absolute distance counter calculated in the routine CALD I ST> in FIG. 6, ie, the absolute distance information outputted from the main CPU 14. Next, in the <AFL> routine, the CCD integration of the focus sensor 20 and the output of the distance measurement calculation value are performed, and the <AF> operation is performed, and the AF
Outputs the calculated output value <ERROR>. Furthermore, <CA
LPDCK> routine uses the depth of field information obtained in the above <CALPD> routine and the above <AFL>
From the AF calculation value obtained in the routine of
Depth of field white determination information is calculated, such as whether the in-focus point is outside or in the depth of field, or whether it is in front or behind.

Next, the calculation of depth of field information in the <CALPD> routine will be described. In general, there are two types of depth: depth of field and depth of focus, but the depth information we want to know now is the depth of field when the relationship between the photographic lens and film is fixed = 27-. The purpose is to calculate information that is converted into depth information on the film side. Then, the direction from the lens to the film is defined as positive. In FIG. 7, X. Suppose that a beam of light projected from an object at a position is extended by an amount X' to extend a lens of focal length f, and is imaged on the film surface. Position X while keeping the distance (fx') from this lens to the film surface fixed. Since the focal point of an object located at a farther distance x1 is at position X4, which is a distance Mt1 closer to the lens from position x3 on the film surface, the image on the film surface becomes a circle of confusion of a certain size. When the diameter of this circle of confusion is the allowable diameter of the circle of confusion δ, the left d1 of the object positions XO and Xl is the rear depth of field. If the difference between the in-focus point on the image side and the film surface at this time is the image-side rear depth of field t1, then the following proportional relationship holds true when the effective diameter of the lens is D.

δ:D-t: (f +x' tt)■ Therefore, tI=-δ(f+x'-tI)/D =-(δ/D)(r+x')/(1+6/D
)=-δ(f/D)(1+x'/f)/(1
+δ/D). Here, if we set f /D = F,
Since F is the F number, 11 = - (δ・P) (L+ x'/D / (L+
δ/D)-1(δ-P)(1+x'/f) ・(f/
(f+δF)1・・・・・・・・・・・・・・・(1)
becomes. Similarly, the image side front depth of field t2 is t2
=δ・F (1+x'/r) /(1−δ/D)=δ・
F(l+x'/r)・(f/(r-δF)1...
・・・・・・・・・・・・(2) Furthermore, if the difference X' between the in-focus point of an object at infinity and the in-focus point of an object at a certain finite distance is related to the count value P of the absolute distance counter by a linear formula, then x'=α 7 ・P It is expressed as β 7 X x . Here α7. β 7 is a constant and
x In this way, by using the allowable circle of confusion diameter δ as lens fixed data, the focal length f as lens-specific data, and the F number F as set aperture value information, it is possible to find the image side depth of field t and t2. can.

By the way, if the main surface of the lens system, the entrance pupil, and the exit pupil do not match, an error occurs in the above equations (1) and (2). Now, assuming that the image side depth of field t1 and t2 are expressed by a linear expression of the count value P, αPi' αF
2'βPi' If βF2 is a constant given as lens-specific data, it is expressed as t1 = -δF (αF1φP + βF1) t2'''6F (aF2°P + βF2), so the constant αF1 that minimizes the error within the necessary range is .βFl'αF2' βF2 combinations can be taken.Also, if the absolute distance is reset at infinity, tl = -δF when P = 0, so βI, 1 = βF2 = 1. Can be done.

Furthermore, αFl'αF is the same throughout the entire count value P.
If approximation cannot be achieved with α2.2, the count value P is divided so that the error can be ignored, and multiple α2. The accuracy can also be increased by setting a combination of β.

FIG. 8 shows the depth of focus t. This is a diagram showing to−δ
It can be expressed as -F (1+x■f) --=·(3), and when δF<f, it can be considered as f/(f±δF)÷1, so it can be set as -tl=t2-to. In this case, considering the lens-specific data αF and βF that minimize the error within the necessary range, -1=1 =δ・F(αF−P
+βF). In fact, δ−0,0
3mm.

F-22, f = 24mm, image side depth of field t1
°t and depth of focus t. The difference is 0.02m at infinity
m (0.66mmφ), 50mm macro equal magnification 0.
Since it is about 0.04 mm (3 mmφ), it can be sufficiently approximated. Moreover, when the image magnification x'/f is (x'/f)<1, (
3) From the formula, t. It is also possible to express it as a value unrelated to the count value P by regarding it as =δ·F. That is, -t1=
Since t2=to, it is also possible to substitute the depth of field on the image side with the depth of focus.

If the output from the set aperture value output means 3 is not given as an F number but as an AV value, in order to convert it to the value of F or δ・F, p=, yAV or δ・F=δHA
It is necessary to calculate V and convert the AV value into an F number. In this case, if 1, D7, δ, F, and δ·F are 7 trixes, they become fixed data.

When to=δF+F−δαF−P, the depth of focus t is obtained from the permissible circle of confusion diameter δ, F number F, constant αF, and count value P. However, (δ·F) may be given as one of the fixed data strings corresponding to the AV value, or unique data may be given in the form of δαF. Alternatively, without depending on the absolute distance count value P, in response to the lens extension (
δα.

(δαFP) may be given as unique data by an encoder or memory configured to output P). If the coefficients including the permissible circle of confusion diameter δ are used as unique data, fixed data is unnecessary, so the fixed data circuit 18b becomes unnecessary. Alternatively, if the set aperture value output means 3 is set to output δ·F as the set aperture value information,
A fixed data circuit 1111b for the permissible circle of confusion diameter δ is not required.

Alternatively, when the set aperture value output means 3 outputs information that corresponds to the AV value or F number but is not proportional to the set aperture value information, the fixed data circuit 18b contains:
(F column' AV or (δF column' AV) is stored as a data column corresponding to each information, and aperture value information is stored in F column.
It can also be converted to a number. It may also be set in the set aperture value output means 3. Further, as the unique data, (αF-P column) corresponding to the count value P, etc. may be set.

Further, as unique data, ft, column, etc. may be set as values corresponding to P and Fl, or P and AV, etc. In addition, the lens data circuit 1 uses fixed data as unique data.
It may be placed in 8a.

Now, if we approximate t = α -11 = α ・t and 1t102t20, it can be expressed as t1 = α1 pi δ・F t2; αt2・δ・F, so lens specific data, set aperture value information,
Focusing on fixed data, it is shown in Table 2 below. Also, if P=0 and 10-δ・F, then βF-1
Therefore, there is no need to treat β as unique data. In this case, as shown in Table 3, the image side depth of field is 11.
12 is tlWαtbiδ・F(αEItP+1)t2moα
t2φδ conflict F(αE11P+1).

Also, if we approximate -t1=to=t2, tl-to
``δ·F(αp'P+βF), so the example shown in Table 4 is obtained.When βF=1 (10≦δF when D=0), the example shown in Table 5 is obtained.

Also, the effective F number F' is F' = F (1+x'/f) --- (4)
Therefore, X' (in the case of f, αF=0 and 1
It can also be approximated as 0−δ·F. In normal cases, the image magnification x'/f of the lens is 115 to l/10, so -t
It may be set as l=t2=to=δ·F.

In the <CALPDCK> routine, the image side depth of field obtained in the <CALPD> routine is compared with the defocus amount of the subject within the focus zone obtained in the AFL> routine, that is, the AF calculation output value (ERROR). do.

If ERROR < t 1, out of focus at rear focus t ≦E
If RROR≦t2, the subject is in focus; if t2<ERROR, the subject is out of focus with the front focus, and the in-focus state of the subject within the focus zone can be checked. FIG. 9 shows an example of how the depth information obtained by <CALPDCK> is displayed as an image within the field of view of the finder.

In FIG. 9, the round display section 40 is an LED that emits green light when energized, and the triangular display sections 41 and 42 are LEDs that emit red light when energized. The display section 40 lights up in green. (ERROR)<
If the pin is from the rear at tl, only the triangular display section 42 lights up in red, and if (ERROR)>t2 is the front pin, only the triangular display section 41 lights up in red to issue a warning. By arranging the display sections 40 to 42 in the finder in this way,
It becomes possible to quickly provide easy-to-understand information to the photographer.

FIG. 10 is an example in which even more subtle amounts of deviation can be displayed. In Fig. 10, the circular display section 43 placed in the center is an LED that can switch between two colors, green and red, and lights up in green when the subject is within the depth of field, and lights up in green when the subject is out of the depth of field. Lights up red and issues a warning. The bar graph sections 44 arranged on the left and right sides of the square display section 4
5 and a diamond-shaped display section 46, for example, a liquid crystal display (hereinafter abbreviated as LCD). The lower square display section 45 indicates the depth of field on the image side of the photographic lens in a certain unit, and the upper diamond display section 46 indicates the depth of field on the image plane side of the photographing lens.
ERRORri of the subject within the focus zone
In other words, the amount of defocus is displayed. Each direction is the same; for example, a shift to the right indicates rear focus, and a shift to the left indicates front focus. This allows the photographer to immediately read the relationship between the subject and the depth.

In addition, the absolute distance determined by the <CALD I ST> routine in FIG. However, you can obtain more information such as depth of field information and absolute distance information when deciding on the composition.

Next, consider displaying hyperfocal distance information together with depth information and the like. As is well known, the hyperfocal distance is the distance that can be considered to be within the depth of field up to infinity.If infinity is at the depth limit at point A in Fig. 11, then the effective diameter of the photographing lens, the allowable circle of confusion diameter δ, and the focal length f Since a similar relationship holds between the lens extension amount x', x' - f=δ=D Therefore, x' = (f/D)・δ = FΦδ ・・・・・・・・・・・・(5 )on the other hand,
Assuming that the object distance is U, as is clear from Figure 13, U=x+f, and from x-x'xf2, x-f2/x' (6) (
Substituting equation (5) into equation (6) gives x=f2/(F·δ).

If the principal point interval is Δ, the absolute distance R is R=x+f+Δ
+f+x' Now, Δ<x, f, x' (If x, f, hyperfocal absolute distance Rh and hyperfocal distance H are respectively Rh=x+2f =f2/(F・δ)+2f H=f2/ (F・δ)+f.

The hyperfocal absolute distance Rh is sufficiently larger than the focal length f,
Even if the focal length f changes depending on the count value P, f
= foo, so the absolute distance is the hyperfocal absolute distance i
Where it is larger than @Rh, it is within the depth to infinity. Alternatively, the object distance U may be determined and compared with the hyperfocal distance H.

Or, if the lens extension amount X' or the count value P is expressed by a linear expression, then X'-α, P+β, ......
(7) X X From formula (5), x' = F·δ. In this case, x
x You can find the hyperfocal distance by placing it. And when P-0, R
If = ■ then β, = 0, P≦α/, F and X
Xteα'8. may be used as unique data (however, α'x/=δ/α).

Further, the hyperfocal length pulse train for each F number may be set as unique data, or αn and βn with the minimum error may be set as unique data. Further, for example, as shown in FIG. 12, the hyperfocal distance display section 48 may be configured to light up and emit light when the camera is focused at the hyperfocal distance. Tables 6 and 7 below show examples of specific data and the like when determining the hyperfocal distance.

FIG. 13 is an optical analysis diagram for examining the depth of field on the subject side. When the focal point on the image side is displaced forward by a minute distance dX°, the subject position moves forward by dx.

Imaging formula based on the focal point position (%) Now, if the absolute distance R, dx is the absolute distance of the shifted point, Rdx = x - dx + f + Δ + f + x' Therefore, R - Rdx = dx =f2/x'-f2/ (x'+dx') Therefore, since X can be regarded as a function of X' by setting it to f2/x', R can be regarded as a function of X'.

R(x')=f2/x'+f+Δ+f+・X'Now,
If the changes in focal length f and principal point spacing Δ are sufficiently small, a,
Using b and c as unique data, it can be expressed as R(x') = a + b' + c''x'.

Similarly, R(x' + dx') -a + (b/(x'+dx') 1+c (x'
10dx') Therefore, by taking the difference between the above two equations, we get R(x') - R(x' + dx') = b/x'
-b/ (x'10dx') -c-dx'Now, if the changes in focal length f and principal point spacing Δ are sufficiently small, then b''=f
2. c~1. Then, (R-Rdx) and (R(x
') - R(x'+dx')) can be said to be dx'.

If dx' is sufficiently small with respect to the absolute distance R, the following approximation holds true.

Rdx' = R (x' + d x') Now, if there is a proportional relationship between the count value P of the absolute distance counter and the image plane movement Q・(8) Also,
Since the ERROR value dx' and the corresponding pulse number dP are dP=α'l -dx', the absolute distance MR can be calculated as -a0(b・α', t )/P 10(C/al,
) ・P=a+b'/P+c' The absolute distance Rdx of the object point focused on the position of P dx' is Rdx
= a + b/(x' + dx') + c (x'
+dx')=a +b/ ((1/(1't)
(P+dP) I+C・+(1/α'xt)(1"
"dP) 1= a + b ■ (P + dP) + c '
The absolute distance can also be calculated directly from the pulse value as (P+dP).

In any case, the unique data α3, or α/X, indicating the relationship between the ERROR value X' and the count value P.

Unique data a indicating the relationship between count value P and absolute distance R,
By using b, c or a, b', c', the absolute distance R can be found using the following formula.

R=a+b/x'+CX' = a + b'/P 10c'PC' is generally a small amount and can be ignored. Or x+dx=f2/ (x'+dx' )=f2/(f
2/x +dx') , °, dx=xf2/ (f2+x-dx') -x
The object distance U is given by U = x + f, x = U - f - L formula f =
α ・P+βf (αf, βf are unique data) U=d+
Approximate as e/P+gP R=a+b'/P+C' P (a, b'c', d, e, g are unique data, and when U and R are approximated linearly, g.

C' is not present) U, f, α 2. Find R, dx from P and Rdx
Rdx can be found as =R+dx. Alternatively, dx=
It may be obtained as '-1/(x+dx')1 to f2H.

Regarding R, Rdx, and dx obtained by the above method,
When dx' = ERROR, these are the absolute distance of the in-focus object point of the lens, the absolute distance of the subject within the focus zone, and the amount of deviation thereof. Further, in the case of t2 in dx'-t1, Rdx and dx are the absolute distances of the depth of field limit and the difference from the in-focus object point of the lens.

Table 8 below is an example of the required 0UTPUT specific data. Note that among the unique data in Table 8, α is unnecessary when f is approximated as constant, and C2C'9g is unnecessary when R and U are approximated by linear expressions.

FIG. 14 and FIG. 15 are display examples within the viewfinder field of view in this case. FIG. 14 shows the depth of field divided from the current position of the lens, and the same parts as in FIG. 10 are given the same reference numerals, and their explanation will be omitted. The scale is logarithmically compressed for easy viewing. A frame 50 with a rear depth of field located at the right end of the figure indicates that the depth is within the depth to infinity. The display example shown in FIG. 15 is quite similar to the distance ring image of a conventional photographic lens, and displays the depth of field and the position of the subject within the focus zone. The bar graph section 53 includes a square display section 52 that displays the lens position and a square display section 5 that displays the subject position.
The absolute distance is digitally displayed on a 7-segment display section 47 with 3 digits in the center.

The scale is either fixed or assigned to each lens depending on the close distance of the lens. Checking whether the depth of field is within the depth of field is performed by blinking the whole or part of the image.

In this way, depth confirmation, depth display, lens focus object point position display, and subject position display in the focus zone can be used not only when AF is locked, but also during continuous AF and ambush A.
Needless to say, even in the case of F, lens movements, changes in depth, changes in absolute distance of the subject, etc. can be used to display images in the finder. In addition, it can be applied not only to interchangeable lens cameras but also to fixed lens cameras.
In that case, the circuit can be simplified by storing the lens data stored in the lens specific data circuit 18a or the lens fixed data circuit 18b in the memory area of the CPU. Furthermore, it is not necessary to perform all of the above calculations, it is only necessary to perform calculations according to the necessary focusing information, and it goes without saying that the lens fixed data is not essential and can be set only when necessary. be.

[Effects of the Invention] As described above, according to the present invention, the relationship between the subject and the depth information of the photographing lens can be easily and accurately determined within the viewfinder field of view, and effective photographic assistance information can be provided to the photographer. have an effect.

[Brief explanation of drawings]

FIG. 1 is a diagram for explaining the present invention in detail, FIG. 2 is a block diagram of an electric circuit mainly for power supply of a camera system to which the present invention is applied, and FIG. Block system diagrams 4 to 6 showing the transmission and reception of signals centering on the AP block in the figure are the AF C
A flowchart showing the program operation centered on the PU, Figure 7 is an optical analysis diagram to explain the depth of field on the image side, Figure 8 is an optical analysis diagram to explain the depth of focus, and Figure 9 is an optical analysis diagram to explain the depth of field. 10 is a front view of an example of a display that outputs and displays focus information, FIG. 10 is a front view of another example of a display that outputs and displays focus information, and FIG. 11 is a hyperfocal An optical analysis diagram explaining depth information at distance. Figure 12 is a front view of the display shown in Figure 9 above with a hyperfocal display added. Figure 13 is a view of the field on the subject side. Optical analysis diagrams for explaining depth, FIGS. 14 and 15 are front views of each display as a further modification of the display shown in FIG. 10 above.

Claims (1)

[Scope of Claims] Absolute distance information output means for outputting absolute distance information in accordance with the movement of the photographic lens; a set aperture value output means for reading the set aperture value information of the photographic lens; and a lens specific to the photographic lens. lens-specific data storage means for storing data; depth-of-field calculation means for calculating depth of field information based on the above-mentioned absolute distance information, the above-mentioned aperture setting information, and the above-mentioned lens-specific data; A distance measurement calculation means outputs the amount of deviation between the in-focus point and the film surface as a distance measurement calculation value, and the focal side depth of the in-focus point of the photographing lens is calculated based on the above-mentioned depth of field information and the above-mentioned distance measurement calculation value. A focusing information output device for a camera, comprising: a depth of field determining means for measuring depth of field; and a focusing information output device for a camera.