Auto focussing method and device

A zoom optical system (25) is associated with an image sensor (46), which is disposed behind the zoom optical system for picking up an object (6). The zoom optical system is focussed by use of a photoelectric signal from the image sensor. In a setup mode, the zoom optical system is zoomed from a first magnification to a preset magnification. The zoom optical system has been set at the first magnification. The preset magnification is adapted to focussing. The zoom optical system is focussed in accordance with the photoelectric signal generated while the zoom optical system has the preset magnification. The zoom optical system is zoomed back from the preset magnification to the first magnification, while keeping the zoom optical system in-focus. The zoom optical system becomes in-focus at the first magnification in a manner in which the zoom optical system is in-focus at the preset magnification.

BACKGROUND OF THE INVENTION 
1. Field of the Invention 
The present invention relates to an auto focussing method and device for an 
optical system. More particularly, the present invention relates to an 
auto focussing method and device for a zoom optical system, in which the 
zoom optical system can be focussed to an object to be photographed 
rapidly and properly even when the zoom optical system is zoomed. 
2. Description Related to the Prior Art 
An auto focussing (AF) device of a contrast detecting type is known. 
Contrast in an image of an object to be photographed becomes the highest 
when the object is sharply focussed. An image sensor known as a 
solid-state pick-up element of a CCD or MOS type is disposed on a focal 
plane of an objective, which is focussed by monitoring a peak of a 
high-frequency component included in a photoelectric signal from the image 
sensor within a predetermined range of frequency. The AF device effects a 
feedback control: the image sensor generates the signal continuously; 
differences in brightness between adjacent pixels are added up; a peak of 
a sum of the added differences is detected. This type is suitable for 
example for a video camera. The contrast detecting type and a phase 
difference detecting type are included in a through-camera-lens (TCL or 
TTL) method. 
An image inputting apparatus for picking up an image to output a video 
signal is known as a variant of a video camera. The image imputing 
apparatus includes an image sensor which picks up the image from a photo 
film or a photo print, and generates a photoelectric signal, which is 
subjected to signal processing. The video signal in form according to an 
NTSC method is produced, and input to a CRT monitor display or a video 
printer. An example of image inputting apparatus is FUJIX FOTOVISION FV7 
(trade name) manufactured by Fuji Photo Film Co., Ltd. 
The image inputting apparatus incorporates a zoom optical system as an 
objective, for enlarging or reducing a size of an image to be observed as 
much as desired. The zoom optical system is placed at as short a distance 
to the object to be picked up as 10-30 mm, as the object is the photo film 
(negative or positive). This is for operability and generally reduced size 
of the image inputting apparatus. Although most of video cameras have a 
zoom optical system of an inner focussing type (rear-focussing type) in 
which a focussing lens is behind a variator lens, it is preferable to 
provide the image inputting apparatus with a front-focussing type of zoom 
optical system in which a variator lens is behind a focussing lens, for 
the reason of keeping optical performance of the zoom optical system under 
the short subject distance. 
The movement of the focussing lens included in the front-focussing type 
inevitably causes a focal length of the zoom optical system to change. If 
the focussing lens is moved according to the contrast detecting technique 
or the phase difference detecting technique after the zooming operation, 
the magnification is changed even after the zooming is finished. This is 
unfavorable particularly when the zoom optical system is zoomed toward a 
Wide-angle terminus. 
If the optical system is zoomed toward the Wide-angle terminus and with a 
small aperture stop, a depth of focus is the greater. When the zoom 
magnification is changed during the focussing, a change in the contrast 
due to the zooming is likely to be more conspicuous than a change in the 
contrast due to the shift of focus. The AF device cannot operate properly, 
because it is likely automatically to follow changes in contrast due to 
the zooming, not due to the shift of focus. 
In the case of the greater depth of focus, the magnification is changed due 
to the set position of the focussing lens within the range of the depth of 
focus. It is highly difficult to determine a zooming position of one 
magnification only by zooming operation. 
SUMMARY OF THE INVENTION 
In view of the foregoing problems, an object of the present invention is to 
provide an auto focussing method and device for a zoom optical system, in 
which the zoom optical system can be focussed to an object to be 
photographed rapidly and without unwanted influences even when the zoom 
optical system is zoomed. 
In order to achieve the above and other objects and advantages of this 
invention, a zoom optical system, in a setup mode, is zoomed from a first 
magnification to a preset magnification, the zoom optical system having 
been set at the first magnification, the preset magnification being 
adapted to focussing. The zoom optical system is focussed in accordance 
with the photoelectric signal generated while the zoom optical system has 
the preset magnification. The zoom optical system is zoomed back from the 
preset magnification to the first magnification, while keeping the zoom 
optical system in-focus, whereby the zoom optical system becomes in-focus 
at the first magnification in a manner in which the zoom optical system is 
in-focus at the preset magnification. 
In a preferred embodiment, the preset magnification is preset high by one 
telephoto position in a zoomable range of the zoom optical system. 
The photoelectric signal, generated while the zoom optical system has the 
preset magnification, is evaluated. The zoom optical system is focussed in 
accordance with evaluation of the photoelectric signal, to form an image 
of the object on the image sensor in an optimized fashion, whereby the 
zoom optical system is set in a reference in-focus condition. A first 
in-focus condition is obtained in accordance with the reference in-focus 
condition, the first in-focus condition being adapted to focussing the 
zoom optical system when at the first magnification. The zoom optical 
system is reset from the reference in-focus condition to the first 
in-focus condition, at a same time as the zoom optical system is zoomed 
back from the preset magnification to the first magnification. 
The zoom optical system includes a variator lens, being movable on an 
optical axis to zoom, and having a magnification position according to 
which a magnification is determined, and a focussing lens, being movable 
on the optical axis to focus, for forming the object image on the image 
sensor. 
Plural tracking data are preset, each of the tracking data representing a 
combination of the magnification position and an in-focus position of the 
focussing lens set on an in-focus condition, there being plural reference 
in-focus positions which the focussing lens has on the reference in-focus 
condition, the plural tracking data being associated respectively with the 
plural reference in-focus positions at the preset magnification. A first 
in-focus position is read in accordance with the tracking data, the 
focussing lens having the first in-focus position on the first in-focus 
condition, the first in-focus position being combined with a first 
magnification position, the variator lens having the first magnification 
position when at the first magnification, whereby the focussing lens is 
set in the first in-focus position when the variator lens is moved back to 
the first magnification position.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT(S) OF THE PRESENT 
INVENTION 
In FIG. 1, an image inputting apparatus is illustrated. An illuminating 
head 3 is disposed in a top of a body 2. The illuminating head 3 includes 
a support 4 in which a slot 4a is formed, and a pair of light source units 
5 supported on the support 4 openably in swingable fashion. A piece of 
developed photo film 6 includes six (6) frames, and inserted in a photo 
film holder 7, which is inserted through the slot 4a. When the light 
source units 5 are turned on, its illuminating light illuminates the photo 
film 6 from its back surface toward the front surface, and in dispersion 
through the photo film holder 7 having translucency of white color. 
A pair of support legs 9 are supported on the body 2 in swingable fashion. 
When the support legs 9 are swung open, the body 2 can stand in an erect 
orientation as depicted. The body 2 incorporates a zoom optical system and 
an image sensor known as a solid-state pick-up element of a CCD or MOS 
type, to pick up an image on the photo film 6 as a still image. The photo 
film 6 may be any of color negative film, color positive film, and 
monochromatic film. A mode selector lever 10 may be operated in accordance 
with the film type, to process a signal required for negative-positive 
conversion. The illuminating head 3 is swingable relative to the body 2 at 
the support 4 as much as 90 degrees, and adapted to either of horizontal 
and vertical orientations in which an image of the photo film 6 is 
recorded. 
It is possible to swing the support legs 9 toward the top over the depicted 
level, and open the light source units 5 to support the body 2 in an 
upside-down orientation. A photo print can be placed on a table under the 
image inputting apparatus, illuminated by the light source units 5, and 
picked up. It is also possible for a user to open the light source units 5 
and hold the body 2 manually like an ordinary video camera, to target 
articles as an object for picking up its image. 
The body 2 includes manual inputs as follows: 
(1) Power switch 11: operated for turning on/off the power source, and also 
for turning on/off an inverter 65 (See FIG. 2) electrically connected to 
the light source units 5. 
(2) AE/AWB (Auto) switch 12: turned on to automate adjustment of color 
(white balance and chrominance) and adjustment of brightness (or 
luminance). When the AE/AWB switch 12 is turned off, then volume dials 
16-20 are rendered effective for manual adjustment of the color and 
brightness of an image. 
(3) Mask switch 13: operable for electrically masking marginal areas inside 
a frame when the frame is displayed in a CRT monitor display, in 
accordance with any status of a panoramically recorded frame and the 
horizontal and vertical orientations. The status set through the mask 
switch 13 is changed in a chained manner, one to another. In other words, 
a selected one of the statuses depends on the number of depression of the 
mask switch 13. 
(4) Mode selector switch 15: operable for selecting one of plural pick-up 
modes. The mode selector 15 is operated when an object to be picked up is 
changed. 
(5) Manual volume dials 16-20: to adjust Red and Blue colors, chrominance 
(C), and brightness (Y). The manual volume dials 16-20 are rendered 
effective when the AE/AWB switch 12 is turned off. 
(6) AF switch 22: to select the auto focussing (AF) or the manual 
focussing, and to start a setup AF mode. 
(7) Manual focussing switch 23: operable for the manual focussing. The 
manual focussing switch 23 is structured as a seesaw type for positive and 
negative directions, and depressed at either of distal ends according to 
one direction as desired. 
(8) Zoom switch 24: operable for zooming. The zoom switch 24 is a seesaw 
type for telephoto and wide-angle directions. 
FIG. 2 is referred to now. A zoom optical system 25 consists of a focussing 
lens 25a and a variator lens 25b, and is a front-focussing type in which 
the focussing lens 25a is nearer to an object to be picked up than the 
variator lens 25b, and movable for the focussing. Note that it is possible 
to dispose a stationary convex lens nearer to the object than the 
focussing lens 25a to set a range optically covering slantingly incident 
beams, in view of a distance of the photo film 6 from the zoom optical 
system 25, as near as 10-30 mm. It is also possible to add a stationary 
lens between the variator lens 25b and the image sensor for compensating 
various aberrations. 
To move the lenses 25a and 25b, stepping motors 26a and 26b are 
individually driven. FIG. 3 illustrates a lens barrel holder 28 containing 
the zoom optical system 25. A top cover 29 is located above the lens 
barrel holder 28, namely in front of the lens barrel holder 28 as viewed 
in FIG. 3. Guide rods 30a, 30b and 30c are fixed between a bottom of the 
lens barrel holder 28 and the top cover 29, and extend in parallel with an 
optical axis. A focussing barrel 31 supports the focussing lens 25a, and 
is guided along the guide rods 30a and 30c. A variator barrel 32 supports 
the variator lens 25b, and is guided along the guide rods 30b and 30c. 
The stepping motors 26a and 26b are secured to a support plate 33, which is 
fixed beside the lens barrel holder 28, namely on the top of the lens 
barrel holder 28 as viewed in FIG. 3. A rotary shaft 34 of the stepping 
motor 26b has a lead screw. A guide rod 35 is fixed on the support plate 
33. A transmission member 36 is supported on the guide rod 35 movably in 
parallel with an optical axis. The rotary shaft 34 is helically engaged 
with a female screw 36a formed in the transmission member 36. Rotation of 
the stepping motor 26b moves the transmission member 36 up and down in 
parallel with the optical axis. Similarly, rotation of the stepping motor 
26a moves another transmission member 37 up and down in parallel with the 
optical axis. The transmission members 36 and 37 have respective forks, 
which are engaged with projections 32a and 31a formed with the variator 
barrel 32 and the focussing barrel 31. The focussing barrel 31 is moved 
inside the lens barrel holder 28 in association with the number of drive 
pulses supplied to the stepping motor 26a. Similarly the variator barrel 
32 is moved in association with the number of drive pulses supplied to the 
stepping motor 26b. 
Photo sensors 39 and 40 are fixed outside the lens barrel holder 28. 
Light-interrupting projections 31b and 32b are respectively formed with 
the focussing and variator barrels 31 and 32, interrupt light, and are 
detected by the photo sensors 39 and 40, to detect respective return of 
the focussing and variator barrels 31 and 32 to home positions. The lens 
barrel holder 28 includes an iris diaphragm motor 42 and a Hall element 43 
(See FIG. 2). The iris motor 42 operates as an actuator for adjusting a 
diameter of openness of an iris diaphragm 45 as illustrated in FIG. 2. The 
Hall element 43 magnetically monitors a shift of a magnet incorporated in 
the iris motor 42, and operates as a sensor for detecting the openness of 
the iris diaphragm 45. A reference numeral 44 designates a flexible 
printed board, which is adapted to supplying the iris motor 42 with 
driving current and receiving an output from the Hall element 43. 
On a bottom of the lens barrel holder 28 is fixed an image sensor 46 to lie 
on the optical axis of the zoom optical system 25. An optical image is 
focussed by the zoom optical system 25 on a photoelectric plane of the 
image sensor 46, and is output by the image sensor 46 in a form converted 
in an photoelectric signal. The whole of the lens barrel holder 28 is 
incorporated in the body 2 in movable fashion in parallel with the optical 
axis, and is settable selectively in an advanced position 10 mm distant 
from the photo film 6 and a retracted position 20 mm distant from the 
photo film 6. The zoom optical system 25 can have a smaller pick-up range 
in the advanced position than in the retracted position. It is possible to 
set two selectable magnifications associated with the advanced and 
retracted positions without zooming the zoom optical system 25, only by 
shifting the zoom optical system 25 to an in-focus position. To detect 
each of the advanced and retracted positions, the lens barrel holder 28 
has a tongue 28a, which is detected by a pair of micro switches 47 as 
illustrated in FIG. 2. 
As illustrated in FIG. 2, the photoelectric signal from the image sensor 46 
is regulated by a gain control amplifier 48 at a suitable level, converted 
into a digital signal by an A/D converter 49, and input into a digital 
signal processing unit 50. The processing unit 50 is controlled by a CPU 
55, and includes a signal processor 50a, an AF circuit 50b, an integrator 
50c, a synchronizing signal generator 50d and an interface circuit 50e. 
The signal processor 50a separates the photoelectric signal into a 
brightness or luminance signal component (Y) and chrominance signal 
component (C), converts them into three color signals, amplifies each of 
the three color signals for the white balance, and subjects those to 
matrix calculation and interpolating process, to generate a digital form 
of video signal. The video signal as a result is converted by a D/A 
converter 51 into an analog signal, which is output by a video amplifier 
52 as a video signal of a composite form or R, G and B forms. 
The AF circuit 50b receives the brightness signal from the signal processor 
50a, and detects differences in the brightness signal between adjacent 
pixels in one zone selected from a full-frame zone FR and a central zone 
SP as preset inside the frame. The differences are generated as absolute 
values (See FIG. 5A). The differences in the brightness signal are the 
higher when a contrast in the image is higher. When a sum of the 
differences peaks, there is a condition of the highest contrast, namely an 
in-focus condition. This processing is equivalent to a technique in which 
a waveform of a brightness signal obtained serially from regularly 
arranged pixels is differentiated to obtain a high-frequency component, to 
determine an in-focus condition according to peaking of the high-frequency 
component. The present invention is applicable to techniques in which the 
brightness signal is treated in the analog form. 
The AF circuit 50b outputs a focus signal as a sum of differences in the 
brightness signal, and supplies a register in the interface circuit 50e 
with the focus signal. The CPU 55 moves the focussing lens 25a while 
monitoring the focus signal being input. Upon peaking of the focus signal, 
the CPU 55 detects an in-focus condition, to determine a set position of 
the focussing lens 25a. 
The integrator 50c receives the brightness signal from the signal processor 
50a, and digitally integrates the brightness signal from one zone selected 
from the full-frame zone FR and the central zone SP as preset inside the 
frame. The integrated value is associated with brightness of the 
full-frame zone FR or the central zone SP. The intensity of the object 
light incident upon the image sensor 46 can be adjusted according to the 
integrated value, to control exposure automatically. To change the 
exposure, it is possible to change a diameter of openness of the iris 
diaphragm 45 or storage time of charge in the image sensor 46. If the 
output level of the photoelectric signal is insufficiently changed, it is 
further possible to adjust gain of the amplifier 48 to control the 
exposure. 
The synchronizing signal generator 50d inputs a synchronizing signal into 
the CPU 55 and a sensor driver 56 for driving the image sensor 46, and 
causes the CPU 55 and the sensor driver 56 to operate in synchronism. The 
circuits in the processing unit 50 are also supplied with the 
synchronizing signal. The image sensor 46, the processing unit 50 and the 
CPU 55 are driven in synchronism. 
The CPU 55 supplies a focus driver 58 and a zoom driver 59 with a drive 
signal. The drivers 58 and 59 supply the stepping motors 26a and 26b with 
drive pulses in the numbers associated with input drive signals, to move 
the lenses 25a and 25b in parallel with the optical axis. The drivers 58 
and 59 respond to commands from the CPU 55, set the frequency of the drive 
pulses selectively at high and low levels, and set the electric current at 
great and small amounts. When the stepping motors 26a and 26b are driven 
at the high speed, the current is set greater to avoid their out-of-step 
state. 
In the setup AF control, the CPU 55 controls the focussing driver 58 and 
the zoom driver 59 to supply the stepping motors 26a and 26b with drive 
pulses of high frequency and greater current, which is described later in 
detail. The variator lens 25b is moved at high speed to a preset 
magnification position preset at a Telephoto terminus. This is a step of 
the "setup magnification changing", which is effected by cooperation of 
the CPU 55, a setup AF program stored in a ROM area of a memory 70, and 
the zoom driver 59. 
After the set position of the focussing lens 25a is determined by the setup 
AF control, the variator lens 25b is returned to the initial magnification 
position. The focussing lens 25a is controlled to move to a set position 
which is obtained in accordance with the preset magnification position of 
the variator lens 25b on the Telephoto side, and the tracking data stored 
in an EEPROM area of the memory 70. This is a step effected by cooperation 
of the CPU 55, the setup AF program stored in the ROM area, the tracking 
data in the EEPROM area, the focussing driver 58 and the zoom driver 59. 
An iris driver 60 receives an iris drive signal having an analog form 
converted by a D/A converter 61. The iris motor 42 is responsively rotated 
to control the open diameter of the iris diaphragm 45. Fluorescent lamps 
in the light source units 5 are driven by a power source circuit 63, a 
DC/DC converter 64 and the inverter 65. The CPU 55 receives a signal from 
the inverter 65, and monitors the on and off states of the fluorescent 
lamps. 
A signal from the Hall element 43 in association with the open diameter of 
the iris diaphragm 45 is entered into an amplifier 66, converted through 
an A/D port, and fed back to the CPU 55. When the focussing barrel 31 and 
the variator barrel 32 pass the respective home positions, signals from 
the photo sensors 39 and 40 are input into the CPU 55. Also a signal from 
the micro switches 47 is input into the CPU 55. 
There are manual inputs 68 and manual volume dials 69, through which 
signals are input in association with the switches 12, 13, 15, 22, 23 and 
24 and the manual volume dials 16-20. The CPU 55 executes various pick-up 
sequences in accordance with those signals. A program of the pick-up 
sequences are stored in a ROM area of the memory 70. In a RAM area of the 
memory 70, various flags and data are written and read during execution of 
the pick-up sequences. Data required for executing the program in various 
manners to the EEPROM area of the memory 70 in the factory manufacturing 
the image inputting apparatus. 
The EEPROM area of the memory 70 stores the tracking adjusting data which 
can be indicated in the curves of FIG. 4. The position of the variator 
lens 25b is taken on a transverse axis of the graph of FIG. 4. The home 
position is defined at a Wide-angle terminus. The Telephoto terminus is 
20.00 mm distant from the home position. The position of the focussing 
lens 25a is taken on an ordinate of the graph. The tracking data (1)-(4) 
are preset in association respectively with four subject distances (object 
distances) frequently used in the image inputting apparatus. In the 
tracking data (1) for example, the zoom optical system 25 can be focussed 
by stopping the focussing lens 25a at 52.8 mm when the variator lens 25b 
is stopped at 15 mm. 
The tracking data (1)-(4) are associated with respective pick-up modes: 
Tracking data (1) is associated with a first pick-up mode, where an image 
on the photo film 6 set in the support 4 is picked up with the lens barrel 
holder 28 moved to the advanced position nearer to the photo film 6. The 
subject distance is set approximately 10 mm, which is the shortest. The 
first pick-up mode is adapted to picking up an image frame photographed on 
the photo film 6 in a horizontal orientation. 
Tracking data (2) is associated with a second pick-up mode, where an image 
on the photo film 6 set in the support 4 is picked up with the lens barrel 
holder 28 moved to the retracted position farther from the photo film 6. 
The subject distance is set approximately 20 mm, which is longer than that 
of the first pick-up mode. The second pick-up mode is adapted to picking 
up an image frame photographed on the photo film 6 in a vertical 
orientation, without vignetting in the picking up. 
Tracking data (3) is associated with a third pick-up mode, where the body 2 
is installed upside down with the support legs 9 widely open, to pick up a 
photo print placed under the body 2. The subject distance is set 
approximately 50 mm. The lens barrel holder 28 remains in the advanced 
position nearer to the photo film 6. 
Tracking data (4) is associated with a fourth pick-up mode, where the body 
2 manually held horizontally like an ordinary video camera, to target 
articles as object to be picked up. The subject distance is set infinity. 
Tracking data (4) is used for limiting the positions. 
When the first, second or third pick-up mode is selected through the mode 
selector 15, a reference value Zt1, Zt2 or Zt3 at the Telephoto terminus 
is selected as reference for calculating the tracking data. The reference 
values at the Telephoto terminus in the respective pick-up modes are 
rewritten each time of effecting the setup AF operation. 
In operation of the auto focussing of the image inputting apparatus as 
constructed above, a main flow in FIG. 5 is referred to first. The CPU 55, 
in the ST1, determines which of the standard AF mode and the setup AF mode 
should be executed. If the first, second or third pick-up mode is set at 
the mode selector 15, then the setup AF mode is selected to come to the 
ST4. If the fourth pick-up mode is set at the mode selector 15, then the 
standard AF mode is selected to come to the ST2. 
In the standard AF mode, selection of either of the AF and the manual 
focussing through the AF switch 22 is detected in the ST2. When the AF is 
selected, an LED disposed near to the AF switch 22 is turned on. The 
standard AF control is effected. In response to the brightness signal from 
the signal processor 50a, the AF circuit 50b generates the focus signal, 
which is entered into the CPU 55 via the interface circuit 50e. It is to 
be noted that the standard AF mode is used differently from the first, 
second and third pick-up modes and adapted to the manual handling by way 
of an ordinary video camera. Only the central zone SP in the frame in FIG. 
5A is used for the AF circuit 50b to obtain the focus signal. No 
background and no nearer object is focussed in the standard AF mode. Note 
that a reference sign S designates a principal object. 
The CPU 55 monitors the focus signal being input successively, and causes 
the focussing driver 58 to drive the stepping motor 26a, to control the 
focussing lens 25a to move until the focus signal peaks. The moving 
control is effected successively each time when photoelectric signals from 
one frame are output from the image sensor 46. 
When the manual focussing is selected in the ST2, then it is judged in the 
ST3 which of the AF and the manual focussing was effected at the previous 
focussing. If the previous focussing is the AF, then a position at the 
Telephoto terminus in association with a presently set position of the 
focussing lens 25a is calculated, to set the calculated position in the 
variable Ztp of reference value at the Telephoto terminus. 
When there is an input through the manual focussing switch 23, the 
focussing lens 25a is controlled to move according to the input. FIG. 4 
illustrates the four curves of the tracking data. For points between the 
curves, the image inputting apparatus is constructed to calculate 
interpolation of each set of two positions on the basis of two curves 
between which the point lies. After obtaining the tracking data with or 
without interpolation, a manual zoom tracking control is effected. With 
the variator lens 25b stopped in a position set through the zoom switch 
24, the set position of the focussing lens 25a is controlled to change 
according to the tracking data as calculated. 
If the setup AF mode is selected in the ST1, then the setup AF control is 
entered upon operation of the AF switch 22 in the ST4. Unlike the standard 
AF control, an object to be picked up is a flat object in the setup AF 
control. The measuring zone is changed to the full-frame zone FR. The 
processing unit 50 generates the focus signal in accordance with the 
brightness signal output from the signal processor 50a regarding the 
full-frame zone FR. The setup AF control is illustrated in FIG. 6, and is 
described later in detail. 
In the setup AF mode, if the AF switch 22 is not operated, then the ST5 is 
entered, to monitor whether there is a change in the pick-up mode. If the 
selected pick-up mode is not changed, then the routine comes from the ST5 
to the ST7. When there is an input through the manual focussing switch 23, 
the focussing lens 25a is controlled to move according to the input. 
If no input from the manual focussing switch 23 exists in the ST7, it is 
judged whether fine adjustment processing is required or not. In the fine 
adjustment processing, the focussing lens 25a is minutely moved in a range 
where a shift of focus is substantially inconspicuous. The focus signal is 
subjected to comparison between values before and after the minute 
movement. If the focus signal has a decrease, then the driving direction 
is reversed. If the focus signal has no decrease, then the driving 
direction is kept unchanged. As a result, the position of the focussing 
lens 25a is adjusted by setting the peak of the focus signal. In general 
the fine adjustment is used when the focus signal has a change beyond a 
certain limit. 
A change in the focus signal beyond the limit takes place, for example, 
when the photo film holder 7 set as illustrated in FIG. 2 is moved to pick 
up another frame after effecting the focussing. There is very little 
change in the subject distance. But the image in the frame changes. The 
brightness signal from the signal processor 50a is remarkably changed, to 
change the focus signal. To be precise, the fine adjustment processing is 
executed when a scene being picked up is changed. Also, the fine 
adjustment processing is effective in overcoming shifts of focus caused by 
a curl in the photo film, mechanical play existing in supporting the photo 
film holder 7, a change in the open diameter of the iris diaphragm 45 due 
to the change in the scene. 
There is an operation of a limiter, associated with the fine adjustment 
processing, for preventing the position of the focussing lens 25a from 
coming conspicuously away from the tracking data as calculated. The EEPROM 
area of the memory 70 stores limit data, by use of which the drive signal 
from the CPU 55 to the focussing driver 58 is limited after the start of 
the fine adjustment processing. The fine adjustment processing is canceled 
upon entry of an input of the manual focussing. 
If there is a change in the pick-up mode in the ST5, the set position of 
the mode selector 15 is checked, to detect a selected one of the first, 
second and third pickup modes. One of the reference values Zt1, Zt2 and 
Zt3 at the Telephoto terminus, which are preset respectively for the 
pick-up modes, is selected. Any selected one of Zt1, Zt2 and Zt3 is set in 
the variable Ztp for calculating the tracking data after the zooming. The 
selected tracking data remains effective before another change in the 
pick-up mode. When the zoom switch 24 is operated, the focussing lens 25a 
is controlled to move as well as the variator lens 25b is moved. 
With one of the first, second and third pick-up modes selected, the AF 
switch 22 is operated. The measuring zone is changed to the full-frame 
zone FR in the ST4, to enter the setup AF control illustrated in FIG. 6. 
The setup AF control includes four steps which are associated with Command 
Code 1-4. The ST10 checks which one of the Command Codes is effective. In 
a flow of a main routine for controlling the entire sequence of operating 
the image inputting apparatus, various steps are executed one after 
another. At the start of the setup AF control, a subroutine of Command 
Code 1 is effected. At first, a position of the variator lens 25b upon 
operation of the AF switch 22 is written to the memory 70. Then Command 
Code 1 is reset while Command Code 2 is set, to terminate the subroutine. 
When the setup AF control is called in the main flow, a subroutine of 
Command Code 2 is effected. The variator lens 25b is moved to the 
Telephoto terminus. The CPU 55 supplies the zoom driver 59 with drive 
pulses for high-speed rotation. The setup AF control can be effected by 
fast movement of the variator lens 25b toward the Telephoto terminus, as 
compared with the zooming commanded through the zoom switch 24 before 
entry into the setup AF control. 
Let the variator lens 25b be located in the Wide-angle terminus when the AF 
switch 22 is operated. It is impossible for the variator lens 25b to move 
to the Telephoto terminus only at one time of the subroutine. The 
subroutine is terminated without changing Command Code 2. Upon calling the 
setup AF control again, the subroutine of Command Code 2 is entered for a 
second time. Then the zoom optical system 25 is moved to the Telephoto 
terminus. Command Code 3 is assigned now. 
The setup AF control is called again, to set Command Code 3 for effecting 
the focussing through the AF circuit 50b. The image magnification is kept 
maximum in the focussing, as the variator lens 25b is positioned in the 
Telephoto terminus. As the object to be picked up is the photo film, 
emulsion grains in dispersed distribution on the photo film support are 
utilized to be focussed. It is therefore possible to focus the object to 
be picked up even when there is no high-contrast object in the measuring 
zone. The iris diaphragm 45 is fully opened during the focussing, so that 
the depth of focus is set small. To adjust the output level of the 
photoelectric signal, storage time of charge in the image sensor 46 is 
changed, or the gain of the amplifier 48 is changed. 
The auto focussing determines the reference value Ztp at the Telephoto 
terminus for calculation of the tracking data. One of Zt1, Zt2 and Zt3 is 
rewritten to be the reference value Ztp at the Telephoto terminus in 
accordance with the present one of the pick-up modes. Then Command Code 3 
is changed to Command Code 4. The present subroutine is terminated. 
Command Code 4 is set, to read the initial position data of the variator 
lens 25b at the time of operating the AF switch 22, namely the position 
data written to the memory 70 while Command Code 1 was set. The variator 
lens 25b is moved back to the initial position in accordance to the 
initial position data as read. To move back the variator lens 25b, the 
zoom driver 59 is supplied with drive pulses for high-speed rotation. The 
variator lens 25b can be moved faster the zooming commanded through the 
zoom switch 24 before entry into the setup AF control. 
The tracking data according to the subject distance has been calculated 
from the set position ztp of the focussing lens 25a at the Telephoto 
terminus. It is possible uniquely to obtain a position to which the 
focussing lens 25a should move in association with a position of the 
variator lens 25b. The CPU 55 supplies the focussing driver 58 with drive 
pulses in accordance with the tracking data, to cause the focussing lens 
25a to move to an in-focus position associated with the first 
magnification position. To stand by for next time of the setup AF control, 
Command Code 4 is changed to Command Code 1. A command of the setup AF 
control is cleared, to finish the setup AF control. 
This being so, the setup AF control makes it possible to focus in the 
magnification position at the time of operating the AF switch 22. Then the 
fine adjustment processing, when desired, is executed by following the 
flow of FIG. 5 from the ST8, as long as there is no further input for 
focussing. Note that, when the image inputting apparatus is initially 
powered, the focussing lens 25a and the variator lens 25b are once moved 
to the home positions, and detected by the photo sensors 39 and 40 for the 
movement thereto. The numbers of the drive pulses supplied during this are 
counted by the CPU 55 to detect the set positions of the lenses 25a and 
25b with reference to the home positions. Then the lenses 25a and 25b are 
moved back to initial set positions upon the powering. It is possible 
subsequently to track the set positions of the focussing lens 25a and the 
variator lens 25b with reference to the home positions. 
When the image inputting apparatus is initially powered, the initializing 
regulating values IZ1, IZ2 and IZ3 are set in the variables Zt1, Zt2 and 
Zt3. One of the pick-up modes are designated according to the set position 
of the mode selector 15. Tracking data associated with the designated mode 
is selected and calculated. When the magnification is changed by the 
zooming, the focussing lens 25a is controlled to move in accordance with 
the tracking data. When the micro switches 47 detect the movement of the 
lens barrel holder 28 to the retracted position, then Zt2 is set in the 
reference value Ztp at the Telephoto terminus. For the setup AF control, 
it is effective to stabilize a white balance control, and limit a feedback 
gain in the exposure control, so as to render changes inconspicuous in the 
color balance and brightness during the zooming. 
The present invention is of course applicable to various pick-up devices 
incorporating a zoom optical system and a solid-state pick-up element. In 
the above embodiment, the preset position to which the variator lens 25b 
is moved is the Telephoto terminus for the setup AF control. However it is 
possible in the present invention that the stepping motor 26b is moved to 
a predetermined telephoto position of a certain high magnification. The 
present invention is also applicable to a zoom optical system in which a 
cam barrel is used for driving the lenses 25a and 25b. In the above 
embodiment the AF device is a contrast detecting type. The present 
invention is applicable to other types of AF devices, such as a phase 
difference detecting type. 
Although the present invention has been fully described by way of the 
preferred embodiments thereof with reference to the accompanying drawings, 
various changes and modifications will be apparent to those having skill 
in this field. Therefore, unless otherwise these changes and modifications 
depart from the scope of the present invention, they should be construed 
as included therein.