JPH04283733A - Automatic focusing camera - Google Patents

Abstract

PURPOSE:To offer the automatic focusing camera which searches for a subject and securely detects the subject whose range can be measured by moving a range finding area when the contrast of the subject is low. CONSTITUTION:When a subject having an effective contrast is not present in the range finding area, a control CPU expands the range finding area by artificial zooming and optical zooming without varying equipment focal determined by optical focal length and artifical focal length so that artifical zoom power becomes maximum.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an autofocus camera having a variable focal length optical zoom lens and a pseudo-zoom function for trimming the photographing range.

0002

2. Description of the Related Art In conventional autofocus cameras, when an effective distance measurement value cannot be obtained, a method called low-contrast scanning is employed in which the lens is forcibly scanned to find the distance measurement value.

0003

[Problems to be Solved by the Invention] However, the above-mentioned low-contrast scanning method is not effective for subjects that have a large defocus amount (Df) and are not within the defocus amount range that allows focus detection. However, if the contrast of the subject is low, it is no longer possible to obtain an appropriate distance measurement value. The present invention solves the above problems, and provides an autofocus camera that can search for a subject by moving the distance measurement area and reliably detect objects that can be measured when the contrast of the subject is low. The purpose is to provide.

0004

Means for Solving the Problems In order to achieve the above object, the invention as set forth in claim 1 provides an autofocus camera having a variable focal length optical zoom lens and a pseudo zoom function for trimming the photographing range. a focus detection means for detecting the focus of the optical zoom lens; a determination means for determining whether the detection result of the focus detection means is valid; and a determination means for determining whether the detection result of the focus detection means is valid; The zoom lens is equipped with a driving means for changing the focal length and the magnification of the pseudo zoom. The invention according to claim 2 is characterized in that the driving means changes the focal length of the optical zoom lens to the shortest focal length side, and
The pseudo zoom magnification is changed to a larger value.

[0005]

According to the structure of claim 1, when the determining means determines that there is no subject with effective contrast within the distance measurement area, the driving means changes the focal length of the optical zoom lens to create a false image. Change the zoom magnification. According to the configuration of claim 2, in the above, the focal length of the optical zoom lens is changed to the shortest focal length side, and the pseudo zoom magnification is increased to expand the distance measurement area. In the following embodiment, this action corresponds to the processes #91 and #92 in FIG. 17.

[0006]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, embodiments of a camera with a pseudo zoom function of the present invention will be described with reference to the drawings. FIG. 1 shows a schematic configuration of an optical system of a camera with a pseudo zoom function according to this embodiment. In the figure, a camera 1 with a pseudo zoom function includes an interchangeable photographing lens 2, a main mirror 3, a focusing plate (primary image plane) 4
, a mirror 5, a mirror 6, a relay lens 7, a condenser lens 8, a field frame (secondary image plane) 9, an infinder optical system 10, a mirror 11, a photometric optical system 12, an eyepiece system 13, etc. . At the bottom of the main mirror 3 is a
An F mirror 14 and an AF sensor module 15 are installed. A pseudo-zoom viewing field 16 indicated by a dotted line and an AF area 17 indicated by a solid line are provided on the focus plate 4. The photometric optical system 12 includes a photometric lens 18 and a photometric element 19
Consists of. The light shielding member 20 for panoramic photography is inserted in front of the field frame (secondary image plane) 9 during panoramic photography to clarify the effective photography area.

In the configuration shown in FIG. 1, the light beam incident from the photographing lens 2 is reflected by the main mirror 3 and forms a full-screen image on the focus plate 4 (primary image plane). The main mirror 3 is a half mirror, and part of the light beam from the photographing lens 2 is guided to the AF sensor module 15 via the AF mirror 14. The AF sensor module 15 measures distances in three areas corresponding to the AF area 17 on the primary image plane. The image on the primary image plane is formed on a field frame (secondary image plane) 9 via a mirror 5, a mirror 6, a relay lens 7, and a condenser lens 8. The relay lens 7 can change the image magnification by moving the lens, and when shooting a full screen, the full screen imaged on the primary image plane is focused on the size of the field frame (secondary image plane) 9. Image.

As the magnification of the pseudo zoom increases, the magnification of the relay system lens 7 increases. For example, 1.
During 4x pseudo zoom, the range indicated by the dotted line on the primary image plane (pseudo zoom visual field range 16) is the field frame (secondary image plane)
The image is formed to a size of 9. The image on the secondary image plane is transmitted to the eyepiece system 1 through a mirror 11 along with the infinder display.
Observed throughout 3. By increasing the magnification of the relay lens 7 as the pseudo zoom magnification increases, you can obtain an image similar to that of a zoom lens in a single-lens reflex camera, but the AF area 17 is located on the primary image plane. Since the size is constant, the AF area 17 appears to be enlarged. The mirror 11 is a half mirror, and the image on the secondary image plane is re-imaged onto the photometric element 19 via the photometric lens 18. The photometry range (in case of split photometry, each photometry range) is
Regardless of the pseudo zoom, it remains constant on the secondary image plane and maintains a constant size relative to the field of view being observed.

FIG. 2 shows a schematic configuration of a focus detection device in this camera. In the figure, TL1 and TL2 are lenses constituting the photographing lens 2. TL1 and TL2 are provided at distances PZ1 and PZ2 (PZ1<PZ2), respectively, from the film equivalent plane FP, which is a planned imaging plane. Hereinafter, these distances PZ1 and PZ2 will be referred to as exit pupil distances. A field mask FM is arranged near the planned image plane FP. The field mask FM has a horizontally elongated first rectangular opening E0 in its center, and a pair of second rectangular openings E01 and third rectangular openings E02 on both sides thereof. The first condenser lens L0, the second condenser lens L01, and the third condenser lens L02 are installed corresponding to the aperture E0, the aperture E01, and the aperture E02, respectively. It is configured to pass and condense a luminous flux of . An aperture mask AM and a re-imaging lens plate L are arranged behind the condenser lenses L0, L01, and L02.

The re-imaging lens plate L includes a pair of re-imaging lenses (L1, L2) arranged in the horizontal direction in the center, and a pair of re-imaging lenses (L3) arranged in the vertical direction on both sides thereof.
, L4) and (L5, L6). These re-imaging lenses L1 to L6 are all plano-convex lenses with the same radius of curvature. Hereinafter, (L1, L
2) is a first re-imaging lens pair, (L3, L4) is a second re-imaging lens pair, and (L5, L6) is a third re-imaging lens pair. Further, the aperture mask AM is arranged just before the re-imaging lens plate L so as to be in close contact with the flat part of the re-imaging lens plate L, and the re-imaging lenses (L1, L2), (L3, L
4), the first diaphragm openings (A1, A2), the second diaphragm openings (A3, A4), and the third
Aperture openings (A5, A6) are provided.

[0011] At the rear of the re-imaging lens plate L, there is a light receiving part PR.
is located. A substrate provided with three CCD line sensors P0, P01, and P02 is disposed in the light receiving portion PR. The CCD line sensor P0 is installed horizontally in the center of the board, and the CCD line sensors P01 and P02 are installed vertically on both sides of the board, in the same direction as the installation direction of the first, second, and third re-imaging lens pairs, respectively. It is located in Each of the CCD line sensors P0, P01, and P02 has two light-receiving element rows, a first and a second, and receives two images re-formed onto the CCD line sensor by a pair of re-imaging lenses. They are configured to perform photoelectric conversion separately. Hereinafter, the CCD line sensors P0, P01, P02 are connected to the opening E0, the opening E01, and the opening E of the field mask FM.
02, they will be referred to as a first CCD line sensor, a second CCD line sensor, and a third CCD line sensor, respectively. The block AFMO surrounded by dotted lines indicates the AF sensor module 14 that is assembled into one piece, and the field mask FM, aperture mask AM, and re-imaging lens plate L constitute a focus detection optical system. .

Next, the structure and operation of the focus detection device when detecting the focus position from the image obtained by the focus detection optical system will be explained. The off-axis distance measuring light beam from the subject in the area outside the optical axis OP of the photographing lens 2, including the principal rays l3 and l4, is directed to the optical axis OP at a predetermined angle with respect to the optical axis OP.
The light enters the field mask FM so as to move away from the light, passes through the second rectangular opening E01, and enters the second condenser lens L01. After this, the light beam is transferred to the second condenser lens L
The light is bent toward the optical axis OP side by 01 and focused,
The second re-imaging lens pair (L3, L4) of the re-imaging lens plate L passes through the second aperture opening (A3, A4) of the aperture mask AM.
). The beam of light incident on the re-imaging lens plate L is
By this second re-imaging lens pair (L3, L4), the second C
This second CCD is focused on the CD line sensor P01.
A pair of images is re-formed in the vertical direction on the line sensor P01.

Similarly, the off-axis ranging light beam including principal rays l5 and l6 is transmitted through the third rectangular aperture E02, the third condenser lens L02, and the third aperture aperture (A5, A6).
, and a third re-imaging lens pair (L5, L6), the light is focused onto the third CCD line sensor P02, and a pair of images is re-formed in the vertical direction. On the other hand, chief rays l1 and l2
The light beam from the object in the area including the optical axis OP of the photographing lens 2 is transmitted through the first rectangular opening E0, the first condenser lens L0, the first aperture opening (A1, A2), and the first refocusing. The light is focused onto the first CCD line sensor P0 through a pair of image lenses (L1, L2), and a pair of images is re-formed in the left-right direction. From the above results, CCD line sensor P0
, P01, and P02, the focal position of the photographic lens 2 with respect to the subject is detected by determining the positions of the three pairs of re-imaged images formed on P01, P02.

FIG. 3 is a view of the field within the finder of this camera. The correspondence relationship with the focus detection device will be explained using the figure. The focus detection area FA on the optical axis is the 1st CC
The D line sensor P0 also has an off-axis focus detection area FA.
1 and FA2 are the second CCD line sensor P, respectively.
01, compatible with the third CCD line sensor P02,
It is configured such that focus detection of objects located in these three focus detection areas with respect to the photographing screen S can be performed. Hereinafter, when it is necessary to distinguish the focus detection areas FA, FA1, and FA2, they will be referred to as a second island, a first island, and a third island, respectively.

FIG. 4 is a functional block diagram of this camera. In the figure, a control CPU 30 controls an external circuit to perform a predetermined operation, and is in charge of controlling the entire camera. The photometry circuit 31 outputs brightness information of the subject to the control CPU 30. Based on this brightness information, the control CPU 30 adjusts the shutter speed (TV value) associated with the exposure operation,
The aperture value (AV value) is determined, and the TV value and AV value are output to the exposure control circuit 32 at the start of exposure. The exposure control circuit 32 instructs the exposure section to perform a predetermined exposure operation based on the TV value and AV value. These TV values, AV values, focus state, etc. are displayed on the infinder optical system 10 and the body by the display circuit 34. Focus detection circuit 3
3 has the above-mentioned focus detection device built-in, performs focus detection of the subject corresponding to each island, and controls the result.
Output to U30. The auxiliary light circuit 35 is the focus detection circuit 3
When distance measurement according to 3 is impossible due to low contrast or low light, auxiliary illumination is applied to the subject to enable focus detection. In this embodiment, the auxiliary light circuit 35 is built into the body, but a flash, etc.
It is also possible to incorporate it into an accessory member. The film sensitivity information circuit 36 outputs film sensitivity information such as ISO sensitivity to the control CPU 30.

The pseudo zoom information writing circuit 37 writes pseudo zoom information on the film surface at the time of photographing. Various writing methods such as magnetic recording are possible. In addition, when the pseudo zoom information is printed at the photo lab,
It is used to specify the trimming range. The pseudo-zoom interface circuit 38 drives the pseudo-zoom motor 39 based on a command from the control CPU 30. This pseudo zoom motor 39 drives the in-finder relay lens 40 to change the finder magnification. The pseudo zoom magnification is controlled by the control CP via the pseudo zoom interface circuit 38.
Transferred to U30. A zoom operation switch 41 is installed on the camera body, and is used to change the pseudo focal length feq in the tele/wide direction by the photographer's operation. Here, the pseudo focal length feq is expressed as feq=foz×fez. Here, foz is the optical zoom focal length, f
ez is a pseudo zoom magnification, and the last printed photograph is equivalent to one taken with a lens of focal length feq. Note that by operating the zoom operation switch 41, the pseudo zoom interface circuit 38 and the optical zoom interface circuit 47, which will be described later, are activated by commands from the control CPU 30.
, or both can operate to obtain the photographer's desired focal length feq. Note that the zoom operation switch 41 can also be provided within the interchangeable lens.

The panoramic photographing switch 42 is a switch for specifying panoramic photographing provided inside the body. Panoramic shooting provides a horizontally long photograph, and when the panoramic shooting switch 42 is turned on, the panoramic light shielding member 2
0 is inserted in front of the field of view frame 9, and at the same time, an instruction to select panorama mode is output to the control CPU 30. FIG. 5 is a diagram showing the relationship between film and print, and (a) is fez=1
, (b) shows the relationship between the film and the print when fez=2, and (c) shows the relationship between the film and the print during panoramic shooting. In the figure, the halftone dot area is the effective exposure area.

Returning to FIG. 4, the AF mode selection switch 4
3 is a one-shot mode in which AF operation is stopped at the same time as focusing, and AF is always performed based on the output of the focus detection circuit 33.
There are two modes: continuous mode, which detects the movement of the subject, and auto mode, which automatically switches between one-shot mode and continuous mode. The focusing lens drive circuit 44 uses a drive signal from the control CPU 30 to
The focusing motor 45 is driven. A focusing motor 45 drives a focusing lens 46 of a photographic lens using a coupler (not shown) to perform focusing.

The optical zoom interface circuit 47 drives the optical zoom motor 48 according to commands from the control CPU 30. The optical zoom motor 48 drives the variable magnification lens 49 of the photographic lens 2 to change the optical zoom focal length foz. Further, the optical zoom interface circuit 47 outputs the focal length to the control CPU 30. The lens ROM 50 stores specific values of the photographic lens 2, such as the aperture f/number. , a focal length range, a coefficient of extension amount per rotation of the coupler, etc., and these information are transferred to the control CPU 30. The switch S1 is a switch that is closed by pressing a release button (not shown) halfway. When the switch S1 is closed, the camera starts up and the photometry and AF operate. The switch S2 is a switch that is closed by pressing the release button, and is an exposure start switch.

FIGS. 6 and 7 are flowcharts showing the processing operations of the control CPU 30. In the figure, first, the state is waiting for switch S1, which is closed by half-pressing the release button, to be turned on (step #1).
), and when switch S1 is turned on, startup processing is performed for all circuits (#2). At this time, the lens ROM
Receives lens information from the camera and initializes the lens position. Initial setting of the lens position means, for example, forcibly driving the distance ring to the infinite position and also resetting a counter for determining the subsequent lens driving amount. Next, check whether the zoom operation switch 41 is operated (
#3), if it is being operated, perform zoom processing (#
4). Next, it is checked whether the panoramic mode is selected (#5), and if it is selected, panoramic zoom processing is performed (#6). Next, it is checked whether the continuous mode is selected (#7), and if it is selected, continuous zoom processing is performed (#8) and the process proceeds to #9. In addition, these zoom processing, panoramic zoom processing,
Continuous zoom processing will be described later.

At #9, a photometric value is input (#9), and then a distance measurement value is input (#10). Next, the reliability of the distance measurement value is checked (#11), and if the input distance measurement value is unreliable, it is determined that distance measurement is impossible and low contrast processing (described later) is performed (#12). If reliable, the distance measurement value that is determined to include the main subject is selected from among the distance measurement values input from the three distance measurement areas (#13).

Next, it is checked based on the selected distance measurement value whether or not the focus is in focus (#14), and if the focus is not in focus, the focus display is turned off (#15) and the focusing lens 46 is driven ( #16). Note that the drive amount is converted from the measured distance value. After the driving of the focusing lens 46 is completed (
YES in #17), it is checked again whether a zoom operation is being performed (#18), and if so, zoom processing is performed (#19), and the process returns to #9. Continue this sequence until focus is achieved. If it is determined in #14 that focus has been achieved, a focus display is performed (#20). After the focus is displayed, check the status of switch S2, which is turned on by pressing the release button (#21), and check whether switch S2 is turned on.
If it is, then check whether it is in panorama mode (#22), and if it is in panorama mode, perform panoramic zoom return processing (described later) (#23), followed by release processing (#24). and return to the start.

[0023] If the switch S2 is not turned on in #21, then it is checked whether the switch S1 is turned on (#25), and if the switch S1 is not turned on,
Assuming that the shooting operation has been canceled, return to the start and again.
Wait until switch S1 is turned on. If the switch S1 is ON in #25, it is next checked whether the mode is one-shot mode (#26). If it is the one-shot mode, the process returns to #21 and the switch S2 is determined again. In this way, in one-shot mode,
After focusing, the AF is locked and the camera waits for the switch S2 to be turned on or for the switch S1 to be turned off, and no focus adjustment is performed. If you are not in one-shot mode in #26,
It is checked whether the continuous mode is selected (#27), and if the continuous mode is selected, the process returns to #9, the next distance measurement and focus adjustment are performed, and the same process is performed thereafter. The focus adjustment is repeated even after focusing. If the continuous mode is not selected, this means that the auto mode is selected as the AF mode, and the process moves to #28, a moving object determination process (described later).

When a moving object is determined in #29, continuous mode is set (#30), continuous zoom processing is performed (#31), and the process returns to #9 to repeat the next focus detection. If it is determined in #29 that the object is not a moving object, one-shot mode is set (#32).
, returns to #21 and proceeds to a loop waiting for S2 to turn on or S1 to turn off. In this way, in the auto mode, it is automatically determined whether the subject is a moving object, and if it is a moving object, the continuous mode is selected, and if it is not a moving object, the one-shot mode is selected.

FIG. 8 is a flowchart showing the zoom processing operation by this camera. First, it is checked whether zoom-up is requested (#41), and if zoom-up is requested, then the optical zoom focal length f
Check whether the oz can be increased (#42). If possible, increase the optical zoom (#43) and return to #41. If this is not possible (when the optical zoom focal length foz is the longest focal length), the pseudo zoom magnification fe
Check whether it is possible to upload z (#44). If possible, increase the pseudo zoom (#45) and return to #41; if not, immediately return to #41.

If zoom-up is not requested in #41, it is checked whether zoom-down is requested (#46). If requested, then check whether the optical zoom focal length foz can be lowered (#4
7). If possible, reduce the optical zoom (#48)
, return to #41. If it is not possible (when the optical zoom focal length foz is the shortest focal length), check whether it is possible to lower the pseudo zoom magnification fez (#49)
. If possible, lower the pseudo zoom (#50) and #
Return to 41. If it is not possible, immediately return to #41. Further, if zoom down is not requested in #46, the process returns. The reason why optical zoom is prioritized for zooming up and down is to avoid changes in the size of the distance measurement area, that is, the ratio of the distance measurement area to the effective exposure area, as much as possible during zooming. be.

The above will be explained using FIG. 9. In FIG. 9, the horizontal axis is the optical zoom focal length foz (here, 35-100 mm optical zoom is assumed), and the vertical axis is the pseudo zoom magnification fez (here, x1 to x2 pseudo zoom is assumed). Further, the equivalent focal length feq is indicated by diagonal lines. Now, point A (foz=50mm, fez=×1
．． 4. fez = 70mm), and when zooming up, control foz and fez as shown in the solid line,
When zooming down, press fo as shown in the dotted line.
Control z and fez.

Next, panoramic zoom processing will be explained using FIG. 10. Generally, in panoramic photography, it is possible to provide a print with a wide horizontal spread, so there is a high probability that the main subject will exist not only at the center of the photographic area but also at the periphery. Therefore, it is better to have a wide range measurement area so that range measurement can also be performed on the peripheral area. In other words, it is effective to increase the pseudo zoom magnification fez to enlarge the distance measurement area. On the other hand, when considering the printout magnification, the effective exposure area is fez=
It is necessary to set it to x1. Therefore, it is preferable to maximize fez during focus adjustment, and set fez=×1 during release (however, fez is not changed).

In FIG. 10, first, it is checked whether the current equivalent focal length feq is within the range of the optical zoom focal length foz (#51). If it is outside the range, a warning is displayed (#52), and the optical zoom is driven so that the equivalent focal length feq is within the range of the optical zoom focal length foz (#53). This means that if the equivalent focal length feq is not within the range of the optical zoom focal length foz, the pseudo zoom magnification fez=× while keeping the equivalent focal length feq constant during shooting.
This is because it cannot be set to 1. Next, the equivalent focal length fe
While keeping q constant, the pseudo zoom and optical zoom are driven so that the pseudo zoom magnification fez becomes the maximum (#54), and the process returns. In #51, if the equivalent focal length feq is within the range of the optical zoom focal length foz, #52, #53
Skip and proceed to #54.

Panorama zoom return processing will be explained using FIG. 11. feq= without changing the equivalent focal length feq
The pseudo zoom and optical zoom are drive-controlled so that fez (fez=x1) is achieved (#61). The operations of the panoramic zoom process and the panoramic zoom return process will be explained using FIG. 12. Now, the pseudo zoom and optical zoom are at point B (foz=100mm, fez=×1.4, feq=1
40 mm), set point C (foz = 7) so that the equivalent focal length feq is within the range of the optical zoom focal length foz.
0mm, fez=×1.4, fez=100mm) (#52 above), and then drive to point D (where the pseudo zoom magnification fez is maximized while keeping the equivalent focal length fez constant) (
foz=50mm, fez=×2, fez=100mm
) (#54). After focus adjustment at point D,
Before the release, point E (foz=
100mm, fez=×1, fez=100mm) (#61), and release processing is performed at point E.

Next, continuous zoom processing will be explained using FIGS. 13 to 15. If the subject is a moving object, if the AF is locked after focusing, the subject may move before the release process and the focus may become blurred, so continuous mode continues focus adjustment even after focusing. is desirable. Figure 13 (a), (b), (c
) shows examples of prints when the values of the distance measurement area and the pseudo zoom magnification fez are varied. As shown in (a), when the distance measurement area is narrow, it becomes difficult to capture the main subject. Therefore, as shown in (b) and (c), it is easier to use if the distance measurement area is expanded by increasing the value of the pseudo zoom magnification fez.

[0032] Therefore, when selecting the continuous mode,
As shown in FIG. 14, as continuous zoom processing, the pseudo zoom magnification f is changed without changing the equivalent focal length feq.
The pseudo zoom and optical zoom are driven so that ez is maximized (#71). That is, as shown in FIG. 15, now point F (foz=70mm, fez=×1.4, feq=
100 mm), point G (foz = 50 mm, fez
= × 2, feq = 100 mm). By performing such processing, a wide distance measurement area can be obtained without changing the equivalent focal length.

Next, a method for selecting a measured distance value will be explained using FIG. 16. In the same figure, first check whether the panorama mode is selected (#81), and if the panorama mode is selected, select the distance value closest to the camera among the three distance values obtained (#82). ), return. When the panorama mode is not selected in #81, it is determined whether the subject magnification β2 of the center ranging area (second island) is greater than or equal to a predetermined value K (#83), and if it is smaller than the predetermined value K, the process is performed in #82. If the value is K or higher, select the distance value in the center distance measurement area (#84) and return.

The reason for performing the above-described processing is as follows. In panoramic mode, the main subject is often placed not only at the center of the screen but also at the periphery, so it is desirable to select the distance measurement value closest to the camera among the three distance measurement areas. Even during normal photography, when the subject magnification β is small, it is generally assumed that landscapes are being photographed, so it is better to select the distance measurement value closest to the camera, as in the panorama mode. However, in general, when β is large, people are often photographed, and the main subject is often placed in the center.
In such a case, select the center distance value. If you select the center distance measurement value, the distance measurement value of the center subject will be selected even if the distance measurement area on the periphery is measuring an object that is closer than the main subject at the center. ing.

Next, low contrast processing will be explained using FIG. 17. Low contrast processing is performed when the distance measurement value is unreliable (during low contrast or low light). In this process, first check the brightness of the subject (#9
1). If it is not dark, there is no object with effective contrast within the distance measurement area. In such a case, if the distance measurement area is expanded, a subject with effective contrast may be included in the distance measurement area, and distance measurement may become possible. Therefore, in order to expand the distance measurement area,
As shown in , the pseudo zoom and optical zoom are driven from point a to point b so that the pseudo zoom magnification fez becomes maximum without changing the equivalent focal length feq (#92). Next, input the measured distance value (#93) and check whether distance measurement is possible (#93).
94), if possible, proceed to #13 without changing the distance measurement area; if not, display low contrast (#95)
, ends the process.

If it is determined in #91 that the main subject is dark, it is considered that effective contrast cannot be given to the main subject due to low light. In such cases, it is effective to provide supplementary lighting. Here, the configuration of the auxiliary light will be explained using FIGS. 19, 20, and 21. FIG. 19 shows the configuration of the auxiliary illumination device portion of this camera. In the same figure, the auxiliary illumination device portion includes a floodlight lens 61 and a first projection pattern 62.
, a second projection pattern 63, a light emitting LED 64, and the like. The light-emitting LED 64 has three light-emitting chips, and condensing lenses 65 and 6 efficiently collect light from each light-emitting chip.
6,67. The three light emitting chips are each set to be able to light up individually. first projection pattern 62,
The second projection pattern 63 consists of a light transmitting part and a light non-transmitting part, and is used to project the pattern onto the subject to provide a contrast of brightness and darkness. be selectively replaced accordingly. Here, the second projection pattern 63 is different from the first projection pattern 6.
It shall have a brightness pattern finer than 2.

FIG. 20 shows the positional relationship between the projected image when the first pattern is set and the distance measurement area at that time. As shown in the figure, the optical zoom focal length foz=35-50
It is possible to provide effective contrast to both the center and the periphery of a distance measurement area of mm, but with an optical zoom focal length of 100 mm, it is not possible to provide effective contrast to the peripheral distance measurement area. Moreover, since only one stripe can provide contrast to the central distance measurement area, the distance measurement performance deteriorates. On the other hand, if a fine pattern is created that provides effective contrast when the optical zoom focal length foz=100 mm, the frequency will be too high and the ranging performance will deteriorate when the optical zoom focal length foz=35 to 50 mm. Optical zoom focal length and pseudo zoom magnification are foz = 35 to 50 mm, respectively.
, fez=×1 to x2, so the first pattern is used when the equivalent focal length fez=35 to 100 mm.

FIG. 21 shows the positional relationship between the projected image when the second pattern is set and the distance measurement area at that time. As shown in the figure, optical zoom focal length foz=100mm
The pattern is finer than the first pattern so that it can provide effective contrast to both the center and the periphery of the distance measurement area. The central illumination light works effectively, but the peripheral illumination light illuminates areas where there is no distance measurement area and is wasted.
For m), it is desirable to turn on only the central illumination light. The second pattern has an optical zoom focal length and a pseudo zoom magnification of foz=100mm and fez=×1 to x2, respectively.
Therefore, the second pattern is used when the equivalent focal length feq is 100 to 200 mm.

The table below shows the relationship between the projection pattern set according to the values of the above-mentioned equivalent focal length feq, optical zoom focal length foz, and pseudo zoom magnification fez, and the illumination area at that time. feq 35 50 100
200foz 35 50 50
100 100fez ×1 ×1
×2 ×1 ×2 pattern 1st
1st 1st 2nd lighting area
All All All Center only Center only

0
Returning to FIG. 17, the flow for achieving the above will be explained. If it is determined in #91 that it is dark, check whether the equivalent focal length feq is smaller than 50 mm (#96
), when smaller than 50 mm, pseudo zoom so that feq = foz without changing the equivalent focal length feq,
Drive the optical zoom (#97). After that, the first fill light
Set the pattern (#98). At this time, since the optical zoom focal length foz is 35 to 50 mm, all three auxiliary lights are turned on (#99). After that, input the measured distance value (#100) and check whether distance measurement is possible (#1
01), set the auxiliary light mode if possible (#10
3), proceed to #13. When this mode is set, auxiliary illumination is performed when inputting the measured distance value. If it is not possible, a low contrast display is performed (#102) and the process ends. In addition,
Even though the optical zoom focal length foz = 35 to 50 mm in #97, the pseudo zoom and optical zoom are driven so that feq = foz.
This is because the frequency of the first pattern and the frequency characteristics of the distance measurement calculation are set to be optimal at an optical zoom focal length of 50 mm.
This is to bring it closer to mm.

If the equivalent focal length feq is 50 mm or more in #96, check whether the equivalent focal length feq is smaller than 100 mm (#104), and if it is smaller than 100 mm,
Drive the pseudo zoom and optical zoom so that foz = 50 mm without changing the equivalent focal length feq (#105
), proceed to #98. If it is 100 mm or more, the pseudo zoom and optical zoom are driven so that foz=100 mm without changing the equivalent focal length feq (#106), and the second auxiliary light pattern is set (#107). At this time,
Since the optical zoom focal length foz=100, only one auxiliary light in the center is turned on (#108), and the process proceeds to #100. Figure 22 shows the foz in zoom processing when emitting filler light.
, fez, and feq. The pseudo zoom and optical zoom are respectively driven from point a to point b, point c to point d, and point e to point f without changing the equivalent focal length feq.

Next, moving object determination processing will be explained using FIG. 23. First, the pseudo zoom and optical zoom are driven so that the pseudo zoom magnification fez becomes the maximum without changing the equivalent focal length feq (#111). This is to widen the distance measurement area when determining a moving object and provide a distance measurement area that will not be missed even if the subject moves. Subsequently, the subject speed v is detected (#112), and the process returns.

[0043]

[Effects of the Invention] As described above, according to the present invention, by driving the pseudo zoom and optical zoom to move the distance measurement area on the subject without changing the equivalent focal length, the contrast of the subject is low. Even when shooting a subject, it is possible to easily search for a subject with effective contrast, and smooth autofocus is possible. Furthermore, by moving the optical zoom to the short focal length side, the range of defocus amount that can be detected remains the same, but the distance range that can be measured for the subject is expanded, making it easier to detect the subject. Become.

[Brief explanation of the drawing]

FIG. 1 is a diagram schematically showing an optical system of a camera with a pseudo zoom function according to an embodiment of the present invention.

FIG. 2 is a diagram showing a schematic configuration of a focus detection device in this camera.

FIG. 3 is a view of the field of view in the finder of this camera.

FIG. 4 is a functional block diagram of the camera.

FIG. 5 is a diagram showing the relationship between the film and the print according to this example, where (a) is feq=1 and (b) is feq=2.
, (c) are diagrams showing the relationship between film and prints during panoramic photography.

FIG. 6 is a flowchart showing processing operations of a control CPU.

FIG. 7 is a flowchart showing processing operations of a control CPU.

FIG. 8 is a flowchart showing zoom processing operation.

[Figure 9] foz, fez, fe in zoom processing
It is a relationship diagram of q.

FIG. 10 is a flowchart showing panoramic zoom processing operation.

FIG. 11 is a flowchart showing a panoramic zoom return processing operation.

[Figure 12] foz in panoramic zoom return processing
, fez, and feq.

FIGS. 13A, 13B, and 13C are diagrams showing distance measurement areas on the film when the value of fez is variously changed.

FIG. 14 is a flowchart showing continuous zoom processing operation.

[Figure 15] f in continuous zoom processing
It is a relationship diagram of oz, fez, and feq.

FIG. 16 is a flowchart showing a processing operation for selecting a measured distance value.

FIG. 17 is a flowchart showing low contrast processing operation.

[Figure 18] foz, fe during low contrast processing
It is a relationship diagram of z and feq.

FIG. 19 is a configuration diagram of a distance measuring element portion in this camera.

FIG. 20 is a diagram showing the relationship between the projection pattern and the distance measurement area when the first pattern is set.

FIG. 21 is a diagram showing the relationship between the projection pattern and the distance measurement area when the second pattern is set.

[Figure 22] Fo in zoom processing when emitting fill light
It is a relationship diagram of z, fez, and feq.

FIG. 23 is a flowchart showing a processing operation for determining a moving object.

[Explanation of symbols]

30 Control CPU 33 Focus detection circuit

Claims (2)

[Claims] 1. An autofocus camera having a variable focal length optical zoom lens and a pseudo-zoom function for trimming a photographing range, comprising: a focus detection means for detecting the focus of the optical zoom lens; and a detection means for the focus detection means. A determination means for determining whether the detection result is valid or not, and a driving means for changing the focal length of the optical zoom lens and changing the magnification of the pseudo zoom when the determination means determines that the detection result is not valid. An autofocus camera characterized by: 2. The autofocus according to claim 1, wherein the driving means changes the focal length of the optical zoom lens to the shortest focal length side and also changes the magnification of the pseudo zoom to a larger value. camera.