JP3976893B2 - Light amount adjusting device and light amount adjusting method - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a light amount adjustment device and a light amount adjustment method applicable to an image pickup device such as an image pickup device such as a video camera and a digital still camera, and a device that needs to control a light amount incident through a lens. .
[0002]
[Prior art]
FIG. 10 shows a configuration of a zoom lens that is conventionally used in an imaging apparatus such as a video camera.
[0003]
FIG. 10 is a cross-sectional view showing a lens barrel structure of a zoom lens composed of four lens groups. FIG. 1A shows a longitudinal section, and FIG. 1B shows a section taken along the line AA in FIG. In the figure, reference numerals 201a to 201d denote four lens groups constituting a photographic zoom lens, 201a is a fixed front lens, 201b is a variator lens group that performs a zooming operation by moving along the optical axis, and 201c. Is a fixed afocal lens, and 201d is a focusing lens group that moves along the optical axis to maintain and focus on the focal plane during zooming.
[0004]
Reference numerals 203, 204a, and 204b are guide bars that are arranged in parallel with the optical axis 205 and guide and stop the moving lens group.
[0005]
Reference numeral 206 denotes a DC motor serving as a drive source for moving the variator lens group 201b. Note that a step motor may be used instead of the DC motor.
[0006]
The variator lens group 201 b is held by the holding frame 211. The holding frame 211 includes a pressing spring 209 and a ball 210 that engages with a screw groove 208 a formed in the screw rod 208 by the force of the pressing spring 209. For this reason, when the screw rod 208 is rotationally driven by the motor via the output shaft 206 a and the gear train 207, the holding frame 211 moves along the guide bar 203 in the optical axis direction.
[0007]
212 is a step motor. The focusing lens group 201d is held by a holding frame 214. A screw member 213 is integrally assembled with the sleeve portion of the holding frame 214, and the screw member 213 rotates the step motor 212 to move the holding frame 214 along the guide bars 204a and 204b in the optical axis direction. Can be moved.
[0008]
Reference numeral 218 denotes an IG meter that drives the aperture unit 235. Reference numeral 220 denotes a camera body equipped with a lens barrel.
[0009]
Next, an electrical configuration in the camera body having the lens barrel structure will be described. FIG. 11 is a block diagram showing the electrical configuration of the camera body.
[0010]
In the figure, reference numerals 201a to 201d denote the four lens groups described above, and reference numeral 201b denotes a variator lens group (variator) for zooming. A focusing lens group 201d serves as a compensator for maintaining a subject at the same distance on the imaging surface by a zooming operation accompanying the movement of the variator lens group 201b in addition to focusing.
[0011]
Reference numeral 221 denotes a solid-state imaging device such as a CCD disposed on the image plane, and 222 denotes a drive source for the variator lens group 201b, which includes a motor 206, a gear train linked to the motor 206, a screw rod 208, and the like. Reference numeral 223 denotes a driving source for the focusing lens group 201d, which includes a step motor and the like. The zoom drive source may be composed of a step motor as in the focusing lens group.
[0012]
Reference numeral 224 denotes an aperture driving source. 225 is a zoom encoder and 227 is a focus encoder. When a step motor is used as a drive source, the lens groups 201b and 201d are respectively arranged at the origin position of the operation by a sensor (not shown) at the initial preparation stage of the operation, and the number of operation pulses input from this position to the step motor is calculated. The method of counting continuously is common. In addition, a volume type or a magnetic type is known.
[0013]
An aperture encoder 226 is known which has a hall element inside a meter as an aperture drive source and detects the rotational positional relationship between the rotor and the stator.
[0014]
A camera signal processing circuit 228 performs predetermined amplification, γ correction, and the like on the output of the CCD. The contrast signal of the video signal subjected to these predetermined processes passes through the AE gate 229 and the AF gate 230. That is, an optimum signal extraction range for exposure determination and distance measurement is set in this gate in the entire screen. Although the size of the gate may be variable or a plurality of gates may be provided, details thereof are not described here for simplicity.
[0015]
Reference numeral 231 denotes an AF signal processing circuit for AF (autofocus), which generates one or a plurality of outputs related to high-frequency components of the video signal. Reference numeral 233 denotes a zoom switch. A zoom tracking memory 234 stores a plurality of pieces of position information of the focus lens group for maintaining the in-focus state following the change of the in-focus position that changes according to the zooming operation according to the subject distance. is there. Note that a memory in the CPU may be used as the zoom tracking memory. A CPU 232 controls the entire system.
[0016]
For example, when the photographer operates the zoom switch 233, the CPU 232 outputs the zoom encoder 225 and the focus encoder 227 so that the predetermined positional relationship calculated based on the information in the zoom tracking memory 234 is maintained. Then, the zoom drive source 222 and the focusing drive source 223 are driven and controlled so that the respective deviations between the target position to be taken by the variator lens group 201b and the target position to be taken by the focusing lens group 201d are 0.
[0017]
In the autofocus operation, the CPU 232 controls the focusing drive source 223 so that the output of the AF signal processing circuit 231 has a peak.
[0018]
Further, in order to obtain an appropriate exposure, the CPU 232 causes the deviation between the output of the aperture encoder 226 and the predetermined value to be 0 so that the average value of the output of the Y signal that has passed through the AE gate 229 becomes a predetermined value. The diaphragm drive source 224 is driven and controlled.
[0019]
In the imaging apparatus using the zoom lens as described above, the aperture of the diaphragm is controlled by driving diaphragm blades of about 2 to 6 by an IG meter.
[0020]
At this time, it is well known that when the aperture diameter of the stop is reduced, the imaging performance is deteriorated (the MTF is lowered) due to the so-called small stop diffraction phenomenon.
[0021]
On the other hand, as described above, in these imaging systems, in order to obtain an appropriate aperture, the aperture diameter is controlled so that the video signal in a predetermined area of an imaging element such as a CCD becomes a predetermined value.
[0022]
For this reason, when the subject is bright, the aperture is quickly reduced, and the above-described image degradation occurs.
[0023]
In order to solve this problem, the following means (A), (B), and (C) have been implemented selectively or in combination.
[0024]
(A) If the exposure is still overexposed even if the aperture is reduced to a diameter at which image degradation due to small aperture diffraction starts to occur, the shutter speed is increased (the charge accumulation time in the CCD is shortened).
[0025]
(B) An ND filter is attached to one or a plurality of diaphragm blades constituting the diaphragm. For example, on the diaphragm side smaller than F5.6, the ND filter covers the entire aperture diameter.
[0026]
As a result, the brightness that reaches the aperture value at which small aperture diffraction occurs is shifted to the bright side by 3 to 4 stages, depending on the ND density, compared to when no ND filter is attached.
[0027]
(C) An ND filter mechanism is provided that allows the ND filter to be inserted into and removed from the optical path instead of attaching an ND filter to the aperture blade. For example, when the ND filter is not inserted into the optical path, If the exposure is overexposed even when the aperture is stopped down to the aperture diameter that generates aperture diffraction, the photographer is prompted to enter ND using, for example, a finder display, and if the photographer enters ND according to this display, Image deterioration due to aperture diffraction can be avoided.
[0028]
[Problems to be solved by the invention]
However, the countermeasures described in the above (A) to (C) have the following drawbacks.
[0029]
That is, in the method (A), when the shutter speed, that is, the accumulation time of the image sensor becomes 1/250 seconds or 1/500 seconds or more, the moving subject is not recorded and reproduced as if it is moving smoothly, The flip-flop and the still image are visually recognized so that the image becomes uncomfortable as a moving image recording. For this reason, in general, this countermeasure is often configured so that the speed of the shutter is automatically increased to about 1/250 seconds at most.
[0030]
The method (B) is a part of the hexagon formed by, for example, six blades where the background bright spot of the subject focused between ND and the F value covering the entire aperture diameter to the open position. It appears as if the ND filter is covered. In particular, when the photographer has an intention to draw including the blur of the background, a blur shape is formed that is contrary to the intention.
[0031]
Although the method (C) compensates for the drawbacks of the method (B) described above, when an ND filter is inserted, the contrast component of the video signal obtained from the CCD is instantaneously reduced at that moment, and this is appropriate. There will be a certain time delay until exposure. That is, as the ND is inserted / removed, the continuity of shooting is interrupted for a predetermined time.
[0032]
Therefore, an object of the present invention is to solve these problems.
[0033]
[Means for Solving the Problems]
In order to solve the above problems and achieve the object, the light amount adjusting device of the present invention includes a diaphragm that adjusts the amount of light transmitted through the lens by making the aperture diameter variable,
ND filter for adjusting the amount of light transmitted through the lens, driving the ND filter from a state where it is completely retracted from the optical path to a state where it is completely retracted, or a state where it is completely retracted from the optical path Is controlled so as to drive the diaphragm in accordance with the driving of the ND filter so that the number of steps for changing the amount of incident light is within the number of steps for changing the amount of transmitted light due to the optical path of the ND filter. And means.
[0034]
In order to solve the above-mentioned problems and achieve the object, the control method of the light amount adjusting apparatus of the present invention is a diaphragm that adjusts the amount of light transmitted through the lens by changing the aperture diameter, and adjusts the amount of light transmitted through the lens. When controlling the ND filter from the state of being completely retracted from the optical path to the state of being completely retracted from the state of being completely retracted from the optical path, or from the state of being completely retracted from the optical path to the state of being completely retracted And a control step of controlling the diaphragm so as to drive in accordance with the driving of the ND filter so that the number of stages to be changed is within the number of changing steps of the amount of transmitted light due to the insertion / extraction of the ND filter into / from the optical path. And
[0059]
DETAILED DESCRIPTION OF THE INVENTION
(First embodiment)
FIG. 1 is a diagram showing two light quantity adjusting means suitable for carrying out the first embodiment of the present invention. In the figure, reference numeral 1 denotes an aperture device, and 2 denotes an ND driving device. 3 to 7 are components of the diaphragm device, 3 is a diaphragm drive meter, 4 is an output shaft thereof, and 5 is an interlocking portion with a meter of a windmill component that rotates around the optical axis in conjunction with the rotation of the output shaft. . This windmill component is provided with an interlocking pin with a blade (not shown), and moves the blade by the rotation of the windmill.
[0060]
Reference numeral 6 denotes a blade. In this figure, an example is shown in which the opening shape is composed of six blades as much as possible to form a hexagon, but this number is not limited to this.
[0061]
In addition, a diaphragm device that does not have a windmill and hooks two blades directly onto an interlocking pin from the output shaft of the meter is widely used and well known, particularly in consumer video cameras.
[0062]
Reference numeral 8 denotes a ground plate, which has a blade rotation center axis and a windmill rotation center at the same time. Reference numeral 7 denotes a blade holding part.
[0063]
Reference numerals 9 to 14 denote components of the ND drive device. 9 is a meter and 10 is an interlocking pin that interlocks with its output shaft. 11 is an interlocking plate, 12 is an ND filter part affixed to the interlocking plate, 13 is an opening, and 14 is a guide of the interlocking plate and is composed of a long groove of the plate and a pin provided on the ground plate. As a result, the ND enters and leaves the optical path by interlocking with the meter. Needless to say, this apparatus is not limited to such a structure in which the plate slides, but may be configured to rotate in conjunction with the rotation of the meter so as to enter and exit the optical path.
[0064]
FIG. 2 shows the configuration of hole detection provided in a meter as a detecting means for detecting the state of these light quantity adjusting means. In the figure, 15 is the rotation center of the meter, 16 is a magnet (rotor), 17 is a hall element, 18 is a coil, and 19 is a case (yoke).
[0065]
When a current flows through the coil, a current is generated perpendicularly to the magnetic field, thereby generating a force and rotating the rotor. At this time, the Hall element is arranged in the vicinity of the boundary position of the polarization magnetized rotor. Therefore, as shown in FIG. 3, the portion where the output changes almost linearly by the rotation of the meter can be read.
[0066]
FIG. 4 is a diagram showing the relationship between the meter rotation angle and the light quantity of the diaphragm apparatus as shown by 1 in FIG. In the figure, the horizontal axis indicates the rotation angle, the vertical axis indicates the amount of light, and 1-7 on the vertical axis indicate that the n-stage spectroscopic amount has been reduced from being opened.
[0067]
For example, if the opening is F1.4, the position 1 indicates F2, the position 2 indicates F2.8, and the position 3 indicates F4. Depending on the shape of the interlocking part between the blade and the pin, in the case of a polygonal diaphragm used in a consumer video camera, the smaller the diaphragm as shown in the figure, the larger the light quantity change tends to occur at a smaller rotation angle. There is.
[0068]
FIG. 5 similarly shows the relationship between the rotation angle of the ND driving means and the change in light quantity. In this example, the aperture is open, and ND is the density at which the amount of transmitted light changes by four steps.
[0069]
6, the horizontal axis 29 shows the A / D value of the hall output of the ND meter shown in FIG. 5, and the vertical axis 30 shows the rotation angle of the meter of the diaphragm shown in FIG. 4 as the A / D value of the hall output. The curves 31 to 36 show two relations (aperture and ND) each having the same amount of transmitted light. When the variable density ND is used, the horizontal axis may be considered as the voltage applied to this means.
[0070]
Reference numeral 31 denotes an interlocking relationship that achieves a transmitted light amount equivalent to a one-stage aperture from the open position. Reference numeral 32 denotes an interlocking relationship for achieving a transmitted light amount equivalent to a two-stage aperture from the open position. The same applies to the following 33 to 36. Assuming that the rotation angle of the ND meter is A / D converted to a value of 0 to 100 by the control means, 0 is a state where ND is completely separated from the optical path, 100 is a state where it is completely included, In the vertical axis, it is assumed that 0 is in the fully open state and 100 is in a state in which it has been narrowed 6 steps from the open state.
[0071]
For example, since the position (point 38) on the horizontal axis 53 and the vertical axis 80 is a point on the curve 33, it corresponds to a three-stage aperture from the open position, and the same amount of transmitted light is obtained when ND is completely separated. It can be obtained even when the aperture is reduced by 3 steps, or when the aperture is open and ND is inserted by 3 steps. In the figure, in each curve, a hatched area 39 in which the aperture meter A / D value is constant indicates a range in which ND does not reach the opening even when the ND meter is moved.
[0072]
FIG. 7 is a simplified diagram assuming that the constant transmitted light amount curve is indicated by a straight line having an inclination of −45 ° in order to facilitate understanding of FIG. 6.
[0073]
In FIG. 7, the vertical axis indicates that the aperture has been reduced by n steps from the opening of the aperture, and the horizontal axis indicates the n-stage (0 to 4) spectral amount from the state where ND is not applied in each open state by ND. The numerical value to be reduced shall be indicated.
[0074]
Therefore, at each position on the horizontal axis, the actual meter rotation angle varies depending on the value on the vertical axis.
[0075]
In the figure, a two-dot chain line 41 shows the relationship between two light quantity adjusting means in a mode (generally referred to as an auto mode, a green mode, etc.) in an average photographing scene when the present invention is implemented.
[0076]
In the figure, (1) to (10) indicate the total incident light amount determined by the stop and the ND filter, and show an example in which a light amount equivalent to a 10-step stop can be obtained from the open position. ing.
[0077]
That is, generally speaking, in order to obtain an amount of light equivalent to an n / 2-stage aperture from the open position, n / 2 stages are obtained by the diaphragm, and the remaining n / 2 stages are obtained by the ND filter.
[0078]
The control means actually stores this relationship as a combination map of AD conversion values to be taken by the two meters of the aperture and the ND filter as described above, and when the optimum exposure is obtained in accordance with the illuminance change of the subject. In accordance with this relationship, the light amount is adjusted while substantially maintaining the characteristics indicated by the two-dot chain line in FIG.
[0079]
According to this characteristic, the ND filter is not applied to the opening at the open position, and a gentle blur can be obtained. Further, when the subject becomes brighter from the open position, the aperture is gradually closed accordingly. Therefore, the depth of field becomes deeper as the depth of field becomes brighter, there is less sense of incongruity, and it is possible to avoid small aperture diffraction over a wide range.
[0080]
If such control is applied, for example, from the fully open position to the second stop position, priority is given to the above-mentioned blurring, and the light amount control is performed only by the diaphragm means, and thereafter, both the diaphragm and ND filter devices are operated. Thus, a configuration in which the light amount control is performed may be used. In this case, in FIG. 7, a characteristic curve is set so as to be obliquely connected to a position corresponding to a 10-stage aperture, which is vertically increased from the open position to 2 on the vertical axis and is then narrowed by 10 stages from the open position represented by (10). (The characteristic curve 41 'in this case is indicated by a one-dot chain line).
[0081]
FIG. 9 is a diagram showing a block configuration of an imaging apparatus suitable for carrying out the present invention. In the figure, reference numerals 47, 48, 51, and 52 denote 1 to 4 lens groups, which constitute a zoom lens. Of these, 48 represents a variator, and 52 represents a focus competition group. Reference numerals 49 and 50 denote an ND filter device and a diaphragm device, respectively.
[0082]
53 is a CCD, 54 is a camera signal processing circuit, 55 is a microcomputer which is a control means (control means), 56 is a storage means provided in the microcomputer, and two light quantity adjustments as described above with reference to FIG. Means relationships are stored in memory.
[0083]
Of the output of the camera signal processing circuit 54, the luminance signal component is taken into the microcomputer, and only a predetermined range of luminance signals in the screen are taken in via a gate (not shown). Yes.
[0084]
Reference numeral 57 denotes a mode selector for switching a photographing mode (program mode), and 58 denotes a manual ND changeover switch. 59 is a diaphragm drive meter, 60 is a detection means for detecting the state of the diaphragm means, 61 is an ND drive meter (or variable ND concentration variable drive means), and 62 is a detection means (or variable density) of the rotation angle state of the ND meter. ND concentration detecting means).
[0085]
That is, when a shooting mode called a green mode, an auto mode, or the like is selected, the relationship between the two-dot chain lines in FIG. 7 is read from the storage means 56, and the interlocking state is maintained while maintaining this relationship. One light quantity adjusting means is operated. In this case, it goes without saying that a proper exposure can be obtained by adjusting the amount of light so that the average value of luminance signal components in a predetermined range of the CCD becomes a target value.
[0086]
(Second Embodiment)
In the second embodiment, although the ND is not manually switched, a control method is proposed that increases the probability of obtaining a beautiful blur by reducing the state where the ND is half applied to the opening as much as possible. is there.
[0087]
A method for this is shown by a characteristic curve 43 drawn by a solid line in FIG. That is, the amount of light is adjusted only by the diaphragm device from the open position to the 4.5th stop, and from here, the amount of light is adjusted by interlocking driving of both the stop and the ND filter between the open position and the 5.5th stop. Thereafter, the side where the light amount is limited again from the 5.5th stage after being opened is the state where the ND is completely entered, and the light amount control is performed only by the diaphragm device.
[0088]
That is, the light amount control in the ND half-hanging state is performed only between 4.5 and 5.5 stages from the opening, but this stage is only one stage. Of course, this is only an example, and the interval may be set without being limited to one stage.
[0089]
A characteristic of such a configuration is that the characteristic curve 43 has a negative slope as shown in FIG. This indicates that, for example, when the light amount adjusting device is operated so that the light amount is decreased from 4.5 to 5.5 from the open position, when the diaphragm device alone is focused, it is driven to open the diaphragm.
[0090]
Depending on the mode selection result of 57 in the block diagram of FIG. 9, such a relationship may be selected. If priority is given to opening, as shown by the broken line 42 in FIG. 7, there are cases in which only the diaphragm is controlled with the transmittance of the ND filter being constant, after which the diaphragm is opened with only the ND filter with the diaphragm open. Conceivable.
[0091]
(Third embodiment)
When inserting / removing the ND filter by a conventional manual operation, for example, the ND is first inserted, thereby darkening the screen for a moment, and then the aperture is driven to the open side to correct this, and the proper exposure is restored. Was working with.
[0092]
In the present embodiment, this problem is solved as follows. That is, as shown by the characteristic curves 44 and 45 in FIG. 8, when the ND is put in and out, the light quantity on the CCD is substantially changed by changing the state of the two light quantity adjusting means of the diaphragm and the ND filter while keeping a predetermined relationship. The ND is completely taken in and out.
[0093]
Here, the difference indicated by 46 is hysteresis, and an optimum value may be set so that hunting or the like is not frequently performed and taking into account frequent ND concentration.
[0094]
In this case, in response to the operation result of the switch 58 in the block diagram of FIG. 9, the ND state instructed by the photographer can be achieved by simultaneously operating the two light quantity adjusting means by the control of the microcomputer.
[0095]
Further, even when the photographer instructs the ND filter to be taken in and out in an arbitrary opening state by the external operation means, the diaphragm can obtain the same amount of transmitted light in each state as shown in FIG. By storing the ND filter interlocking relationship in advance, if the aperture is controlled according to the stored information and the ND filter is controlled, it is possible to switch the ND filter while maintaining the continuity of imaging.
[0096]
According to the above embodiment, the state of each light amount adjusting means, for example, the state of the aperture diameter in the diaphragm device, the state in which ND is applied in the ND loading / unloading device, or the density state in the variable density ND, etc. In the case of a device or ND drive device, the detection result of the rotational angle of the rotor by a Hall element provided in the drive meter, or if these devices are driven by a step motor, the number of drive steps from the reference position, or in the case of a variable ND device The result of directly measuring the amount of transmitted light by the light emitting element and the light receiving element provided between the NDs or the voltage applied to the transparent electrode can be detected, and this information is input to the control means. Furthermore, the control means determines one or a plurality of combinations of the states of these means in advance when adjusting the light quantity, and performs light quantity control according to this combination.
[0097]
More specifically, for example, in a state where the aperture is wide open to a relatively wide aperture, the light amount is adjusted only by using the aperture means so that the blur is not lost. ND is gradually put into the optical path before the diaphragm causes image degradation due to diffraction phenomenon caused by the small stop (the density of the variable density ND is gradually increased). The diaphragm means is driven to optimize the change in the light amount on the image plane that changes with the insertion (change in the density of the variable density ND). Here, the ND enters the optical path (the density of the variable density ND). Depending on the state, instead of feedback from the light amount on the image plane, smooth light amount control is achieved by operating in a relationship in which the aperture diameter is determined in a predetermined relationship with this state.
[0098]
In addition, when the ND is taken in and out in the same manual operation as in the prior art, in this case, the light quantity on the image plane is kept almost constant by determining the combination of the states of the two means under the condition that the transmitted light quantity is constant. The ND can be manually put in and out while being leaned, so that proper exposure can be maintained even if this operation is performed.
[0099]
Also, depending on the camera mode, for example, the auto mode and other modes that can obtain an average scene for the majority of shooting scenes in the auto mode, for example, two light levels between low-light subjects and bright subjects The adjusting means is configured so that either one of the regions operates, and even when both operate simultaneously, the respective movements are in the same direction. That is, when the amount of light is reduced, the ND further enters the optical path ( (In the case of variable density ND, the direction in which the density increases), and the diaphragm is operated so that the aperture becomes smaller. In another mode, for example, portrait mode, ND has an aperture diameter as much as possible to give priority to blurring. In order to avoid the state of covering the middle of the ND, so that the movement of the ND state is completed within a short illuminance change range, the aperture is opened while the ND enters. Due eggplant, and it makes it possible to light amount control adapted to the intended mode selection.
[0100]
In this way, in addition to the so-called diaphragm device that makes the aperture diameter variable, there is a second light quantity adjusting means that makes the so-called T number variable such as an ND filter or a density variable ND filter that can be taken in and out of the optical path. Various conventional problems are solved by controlling the two adjusting means in a predetermined relationship by the control means. That is,
(1) A transmission light amount adjusting means such as an ND filter is continuously and automatically applied to the optical path in accordance with a change in the brightness of the subject so as to prevent occurrence of small aperture diffraction while ensuring a blur on the open side. (The variable density filter increases the density).
(2) When the ND enters (the variable density filter is colored), it is operated with a predetermined relationship between the condition of the entry (coloring condition) and the aperture diameter. When the ND is taken in and out, the optimum exposure state that has been interrupted for a moment to several seconds can be made uninterrupted.
{Circle around (3)} By making the relationship between the plurality of light quantity adjusting means different in accordance with the mode state of the camera, it is possible to take a photograph reflecting the photographer's intention most.
[0101]
【The invention's effect】
As described above, the light amount is controlled by combining the light amount adjusting means for changing the aperture diameter and the light amount adjusting means for adjusting the light amount by a method other than the change of the aperture diameter, for example, by changing the transmittance. In addition, it is possible to perform optimal light amount adjustment giving priority to image quality in consideration of depth, diffraction, and the like without causing an unnatural change in the image.
[Brief description of the drawings]
FIG. 1 is a perspective view showing a configuration of a light amount adjusting device of the present invention.
FIG. 2 is a configuration diagram of a meter as detection means for detecting the amount of movement of the light amount adjustment means.
FIG. 3 is a diagram illustrating the detection characteristics of FIG. 2;
FIG. 4 is a diagram illustrating a relationship between a rotation angle of a meter of a diaphragm device and a light amount.
FIG. 5 is a diagram showing a relationship between a rotation angle of an ND meter and a light amount change.
FIG. 6 is a characteristic diagram showing the relationship between the rotation angle of each of the ND meter and the diaphragm device meter by the A / D value of the Hall element.
7 is a simplified diagram of the characteristics of FIG.
FIG. 8 is a diagram for explaining a third embodiment of the present invention.
FIG. 9 is a block diagram showing a configuration of a video camera body to which the present invention is applied.
FIG. 10 is a diagram illustrating a configuration of a general zoom lens.
FIG. 11 is a block diagram illustrating a configuration of a video camera body.
[Explanation of symbols]
1 Aperture device (first light intensity adjusting means)
2 ND driving device (second light amount adjusting means)
3 Aperture drive meter
9 ND drive meter
55 Microcomputer (control means)
59 Aperture drive meter
60 Aperture detection means
61 ND drive meter
62 ND detection means

Claims (6)

A diaphragm that adjusts the amount of light transmitted through the lens by making the aperture diameter variable,
An ND filter for adjusting the amount of light transmitted through the lens;
When controlling the driving of the ND filter from a state where it is completely retracted from the optical path to a state where it is completely retracted, or from a state where it is completely retracted from the optical path to a state where it is completely retracted, the number of steps for changing the amount of incident light is Control means for controlling the diaphragm to be driven in correspondence with the driving of the ND filter so as to be within the number of steps of change of the transmitted light quantity due to the insertion / extraction of the ND filter into / from the optical path. apparatus. Storage means for storing a characteristic curve indicating a combination of control values to be taken by the diaphragm and the ND filter in order to control the target control stage number;
When the control means controls the driving of the ND filter from a state of being completely retracted from the optical path to a state of being completely entered, or from a state of being completely entered to the optical path to a state of being completely retracted, 2. The light amount adjusting device according to claim 1, wherein the diaphragm is controlled to be driven corresponding to the driving of the ND filter so as to maintain the relationship indicated by the characteristic curve stored in the means.   The control means adjusts the amount of light only with the diaphragm until the limit of occurrence of small aperture diffraction. 2. The aperture is driven to the open side, the ND filter is inserted into the optical path, and when the ND filter is completely in the optical path, the light amount is adjusted only by the aperture. The light quantity adjusting device described in 1. A diaphragm that adjusts the amount of light transmitted through the lens by making the aperture diameter variable,
An ND filter for adjusting the amount of light transmitted through the lens;
When controlling the driving of the ND filter from a state where it is completely retracted from the optical path to a state where it is completely retracted, or from a state where it is completely retracted from the optical path to a state where it is completely retracted, the number of steps for changing the amount of incident light is And a control step of controlling the diaphragm so as to drive in accordance with the driving of the ND filter so as to be within the number of steps of change in the amount of transmitted light due to the insertion / extraction of the ND filter into / from the optical path. Method. In order to control to the target number of control stages, it has a storage process storing a characteristic curve indicating a combination of control values to be taken by the diaphragm and the ND filter,
The control process is performed when the driving of the ND filter is controlled from a state where the ND filter is completely retracted from the optical path to a state where the ND filter is completely retracted from a state where the optical path is completely retracted. 5. The light quantity adjustment method according to claim 4, wherein control is performed so that the diaphragm is driven in correspondence with driving of the ND filter so as to maintain the relationship indicated by the characteristic curve stored in the process. In the control process, the light amount is adjusted only by the diaphragm until the limit of occurrence of small aperture diffraction, and when the limit of occurrence of small aperture diffraction is reached, the ND filter is in a state of being completely in the optical path. drives the aperture to the open side, the ND will put the optical path a filter, when the ND filter is fully in a state of entering the optical path, according to claim 4, characterized in that the light quantity adjustment by only the throttle The light quantity adjustment method as described in 2.

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