JP4217325B2 - Light control device - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an ND filter driving device, a light amount adjusting device, and an image pickup device, and more particularly to a light amount adjusting device used for an image pickup device such as a video camera or a digital camera, and particularly to driving an ND filter provided separately from a light amount adjusting member.
[0002]
[Prior art]
In a video camera or a digital still camera as an image pickup apparatus that records a moving image or a still image using a solid-state image pickup device such as a CCD, especially in the field of consumer equipment, so-called 1/3 is accompanied with the progress of fine semiconductor processing technology. Small-size solid-state imaging devices called inches, 1/4 inches, and 1/5 inches are most commonly used. For example, a size called 1/4 inch has a diagonal length of about 4 mm and has about 400,000 pixels.
[0003]
Since these image sizes are significantly smaller than, for example, a diagonal length of 43 mm of 135 film, a lens with the same angle of view can generally be significantly reduced in size with respect to a lens of a film camera. Actually, in a video camera using a 1/4 inch CCD, the zoom lens has a zoom ratio of 10, and the total length is reduced to about 50 mm.
[0004]
A general configuration of a zoom lens used in such an image pickup apparatus is illustrated. 12 Shown in
[0005]
Various types of inner focus lenses are known. 12 Is composed of four groups, and shows a configuration in which the rearmost lens group is used for focusing. Figure 12 , 111 is a fixed front lens group, 112 is a variator lens group, 113 is a fixed lens group, and 114 is a focusing (compensation) lens group.
[0006]
133 is a guide rod for preventing rotation, 134 is a feed rod for the variator lens group 112, 135 is a fixed barrel, 136 is an aperture unit (here, inserted perpendicular to the paper surface), and 137 is a focus motor. A step motor 138 is an output shaft of the step motor 137, and a male screw 138a for moving the focusing lens group 114 is processed. Reference numeral 139 denotes an internal thread forming portion that meshes with the external thread 138a, and is integrated with the moving frame 140 of the lens 114.
[0007]
141, 142 are guide rods for the lens 114, 143 is a rear plate for positioning and holding the guide rods 141, 142, 144 is a relay holder, 145 is a zoom motor, 146 is a reduction gear unit of the zoom motor 145, 147, 148 Is an interlocking gear, and the interlocking gear 148 is fixed to a zoom feed bar 134.
[0008]
Next, the operation will be described. When the step motor 137 is driven, the focus lens 114 moves in the optical axis direction by screw feeding. When the zoom motor 145 is driven, the screw shaft 134 is rotated via the interlocking gears 147 and 148, and the variator 112 held by the lens frame 112a screwed with the screw shaft 134 moves in the optical axis direction.
[0009]
Note that a step motor may be used as the zoom motor in the same manner as the focusing lens described above.
[0010]
Also, figure 12 In the description, the variator lens group uses a DC motor 145 as a drive source, and as a position detection, for example, a brush integrally attached to the variator moving ring is configured to slide on a substrate on which a resistance pattern is printed. Detect with a volume encoder.
[0011]
Even if this method is not used, like the focus, a step motor is used as the drive source, and the number of drive input pulses to the step motor is continuously counted based on the reset position, and the absolute position of the lens group is determined. A method of knowing may be used.
[0012]
A method using a photo interrupter is well known for detecting the reference position when using such a step motor.
[0013]
Further, as a driving source of each movable lens group, a DC motor with a gear head described above, a step motor, a voice coil type, and the like are also known.
[0014]
Next, a light amount adjustment method in an imaging apparatus using such a zoom lens and the above-described solid-state imaging device such as a CCD will be described.
[0015]
Figure 13 These are block block diagrams explaining this light quantity adjustment method.
[0016]
Reference numeral 201 denotes a light amount adjusting device, for example, an aperture device. Reference numerals 202 and 203 denote diaphragm blades as light quantity adjusting members, 204 denotes an opening, and 205 denotes an open opening provided on the base plate.
[0017]
Reference numeral 206 denotes a rotor magnet (not shown) to which the output shaft 210 is fixed, a yoke, and a drive unit called a meter unit constituting a magnetic circuit by a coil wound around the yoke. Reference numeral 207 denotes an arm fixed to the output shaft 210. The levers 208 and 209 are interlocking portions of the arm lever 207 and the blades.
[0018]
211 is a solid-state imaging device such as a CCD, 212 is an amplifier circuit, 213 is a camera signal processing circuit, 214 is a recorder, 215 is a gate, 216 is a means for changing the size and position of the gate 215, 217 is a manual switch, and 218 is an average luminance It is a level calculation circuit.
[0019]
Further, 219 is a mode changeover switch of the image pickup device, 220 is a backlight correction switch, 221 is a timing generator, 222 is a CPU, 223 is a memory provided in (or outside) the CPU 222, and 224 is a CCD drive circuit. The example includes a variable circuit of charge accumulation time (shutter speed). 226 is an aperture encoder, and 227 is an aperture drive circuit.
[0020]
In the above, the subject image formed on the CCD 211 is converted into an electric signal as a charge amount for each pixel corresponding to the intensity of the brightness, amplified by the amplifier circuit 212, and then by the camera signal processing circuit 213. Processing such as predetermined gamma correction is performed. Note that this processing may be performed by digital signal processing after A / D conversion.
[0021]
The video signal created in this way is recorded by the recorder 214.
[0022]
Of the video signal, the contrast signal (Y signal) is extracted by the gate 215 only from the contrast signal at a predetermined position in the screen (for example, a small area at the center of the screen). The average luminance level calculation circuit 218 extracts the contrast signal. An average value of the contrast signals obtained is calculated. The calculated average value is taken into the CPU 222.
[0023]
Reference numeral 217 denotes a manual switch that can be switched by the photographer in relation to the size of the gate 215. For example, a measurement area such as a center weight or a spot can be designated. Based on these area designation results or the area designation results determined by the CPU 222, the size position varying means 216 can change the position and size of the gate 215. Of course, the position varying means 216 and the manual switch 217 are not necessarily required.
[0024]
The CPU 222 calculates whether or not the fetched average luminance size matches the numerical value corresponding to the appropriate exposure stored in the CPU, and if there is a difference, the CPU 222 calculates the difference according to the sign and absolute value of the difference. Then, the aperture of the diaphragm is changed, or the charge accumulation time in the CCD 211 is changed.
[0025]
When the diaphragm is moved, the output shaft 210 and the arm lever 207 rotate when a current is passed through the coil of the electromagnetic meter by the diaphragm driving circuit 227. Since the arm-side pin and the groove at the tip of the blades 203 and 202 are fitted at the tip of the lever, the two blades 202 and 203 slide up and down as the lever 207 rotates. As a result, the size of the opening 204 changes.
[0026]
In this way, the optimum exposure can be obtained by changing the aperture area or the charge accumulation time so that the above-mentioned average luminance level becomes a predetermined value.
[0027]
Here, in the camera mode Sw219, a shooting mode such as a portrait mode or a green mode (automatic exposure mode) is selected. Thus, an aperture value and a shutter speed can be set even for the same subject depending on the photographer's intention to draw. Are selected in a way that meets their intent. A plurality of so-called “program diagrams” of the exposure program for this purpose are stored in the memory 223. Further, when the backlight correction switch 220 is operated, processing such as changing the predetermined value of the average luminance level to a level higher by two to three steps is performed.
[0028]
Here, in determining the combination of aperture shutters stored in the memory 223, the following (1) , (2) , (3) The following three constraints occur.
[0029]
(1) According to the standard television format (NTSC in Japan), the charge accumulation time cannot generally be made slower than 1/60 second.
[0030]
(2) In order to record a smooth motion without a sense of incongruity on a moving subject as a moving image, it is not possible to set a shutter speed that is too high (setting a short charge accumulation time). 1/250 seconds as a guide.
[0031]
That is, the above (1) ~ (2) With the shutter speed, you can only adjust the exposure for about two steps. As a further constraint,
(3) If the F value is set to F16 on the 1/3 inch side and the aperture (smaller aperture value) side than F11 on the 1/4 inch side, the aperture diameter of the aperture is reduced, and the imaging performance is deteriorated due to diffraction. Figure 14 FIG. 2 is a diagram illustrating this state as an image.
[0032]
Figure 14 , The horizontal axis indicates the FNo of the stop, and the vertical axis indicates the MTF as the imaging performance. The MTF is a numerical value indicating how much the contrast of the subject is maintained on the imaged surface. A higher value is preferable. Actually, the value changes according to the spatial frequency.
[0033]
The open MTF is slightly improved when the aperture is reduced. This reflects, for example, that spherical aberration has been improved by reducing the aperture. Moreover, the aperture value is a value that causes diffraction by the small aperture described above (F _th ) Exceeds this value, the MTF decreases due to this influence.
[0034]
This F _th If the aperture can only be controlled on the brighter side, a lens with an open aperture of about F1.4 will have about 6 steps of light, depending on the screen size. Adjustment I can only do that.
[0035]
Therefore, the amount of light can only be adjusted by about 8 steps with the aperture and shutter, and the number of steps is insufficient.
[0036]
For this reason, in an actual imaging apparatus, an ND filter is often attached integrally to a diaphragm blade. Figure 15 (A)-(D) have shown the mode of opening from the state (D) to which the ND filter covers all the aperture diameters from an open | release (A) when the ND filter 230 is affixed on the blade | wing 203. FIG. ND density reduces transmitted light amount (1/2) ^Three = 1/8, that is, if the density is reduced to three steps, the light intensity in the practical range of the subject brightness from the above 8 + 3 = 11 Adjustment Can be achieved.
[0037]
[Problems to be solved by the invention]
However, this also had the following problems.
[0038]
・ When the ND density is increased, shading of the brightness of the top and bottom (the top and bottom parts of the lower part where the ND filter is closed and the upper part without the ND filter) occurs, and even a subject with uniform brightness may not be recorded with uniform brightness. .
[0039]
-As a bokeh, the shape of the ND filter can be seen in the shape of the aperture, so the quality is poor.
[0040]
・ With further downsizing and higher density of CCD, F _th When the value of F is brighter up to F8 or F5.6, the current method is sufficient Adjustment The range cannot be obtained.
[0041]
For this reason, instead of sticking to the blades in this way, an ND filter is provided so that it can be taken in and out of the optical path. _th It is well known that the CPU instructs the EVF (electronic viewfinder) or the like to insert / remove the ND filter based on the comparison of the above, and the photographer performs the ND filter insertion / removal operation. There was a problem that the continuity of shooting was interrupted between the moment of taking in and out and the time when the proper exposure was obtained again.
[0042]
Furthermore, for the purpose of solving this problem, the present applicant maintains the predetermined interlocking relationship controlled by the CPU between the diaphragm device and the ND filter device, thereby ensuring the continuity and the blurring. Has achieved.
[0043]
However, even with this method, the density of the ND filter is high and the ND filter is open. The When shooting is performed in a state where the half is covered, the above-described luminance shading problem is difficult to avoid. In addition, if the ND filter density is reduced to avoid it, sufficient light quantity is obtained. Adjustment The number of stages cannot be obtained.
[0044]
Figure 16 Is a figure 13 2 shows an example of a program diagram of the memory 223 of FIG. In the program diagram shown by the solid line, the shutter speed (charge accumulation time) of 1/60 sec is first maintained and the aperture is F. _th If the shutter speed is reached, the shutter speed is increased to 1/250 sec. If the exposure is still overexposed, it is unavoidable (small aperture diffraction occurs), but a smaller aperture is used.
[0045]
On the other hand, a program diagram indicated by a two-dot chain line is an example in which it is desired to make the depth of field as shallow as possible, and the shutter is first raised to 1/250 sec after opening.
[0046]
In a shooting scene that does not give a sense of incongruity as a moving image, if it is desired to open the aperture as much as possible, a program diagram indicated by a broken line may be used.
[0047]
The purpose of the invention related to this application is to consider the amount of light taking into account the prevention of vertical shading. Adjustment Can achieve Light control device Is to provide.
[0048]
[Means for Solving the Problems]
The first configuration of the ND filter driving device that realizes the object of the invention according to the present application is effective in a plane substantially perpendicular to the optical axis by the driving means and the driving means. Light path Can be put in and out Driven by With ND filter , A light amount adjustment state detection means for detecting the light amount adjustment state by the light amount adjustment member, a position detection means for detecting the position of the ND filter relative to the inside and outside of the effective optical path, detection information of the light amount adjustment state detection means, and detection information of the position detection means Based on the control means for controlling the driving of the first driving means and the second driving means, ND filter driving device having Because ND filter , Effectiveness Light path Valid from outside Light path When entering, A first ND filter region that first enters the effective optical path; and a second ND filter region that has a lower transmittance and a smaller area than the first ND filter region, and the control means includes: As long as the light quantity adjustment state detected by the light quantity adjustment state detection means is from the first opening diameter (including the open diameter) to the second opening diameter smaller than the first opening diameter, the second driving means. By driving the first ND filter region into the effective optical path, the opening formed by the light amount adjusting member is covered with the first ND filter region, and the light amount adjustment state detected by the light amount adjustment state detecting means However, when the diameter changes to the smaller diameter side than the second opening diameter, the second driving means is further driven in the same direction to cause the second ND filter region to enter the effective optical path, thereby adjusting the light amount adjusting member. By shape It has an opening which is to cover the second ND filter area .
[0063]
DETAILED DESCRIPTION OF THE INVENTION
( For reference First embodiment)
1 and 2 show the present invention. Reference in The first of of Embodiments are shown.
[0064]
In FIG. 1, the ND filter is retracted from the optical path. In FIG. 13 The members having the same functions as those shown in FIG.
[0065]
238 and 239 are ND filters having different densities (transmittance), 238 is a filter having a relatively low density (large transmittance), and 239 is a filter having a higher density (small transmittance) than 238. is there.
[0066]
These ND filters 238 and 239 may be made of film in addition to glass.
[0067]
Also, one density filter material is arranged at the positions of the filters 238 and 239, one ND filter 238 is composed of only this common filter material, and the other filter 239 is further overlapped with this one density filter material. When the ND filter is manufactured, the filter 238 and the filter 239 may be manufactured to have two different concentrations. Here, both the filter 238 and the filter 239 are configured to have an area capable of completely covering the aperture diameter 205 of the diaphragm.
[0068]
231 is a meter unit which is a driving means for the ND filter, 232 is an output shaft of the meter, 233 is an interlocking lever, 234 is a pin at the tip of the lever, 235 is formed in an operating part of a frame member 237 for holding the ND filter A long groove 236 indicates the rotation center of the frame member 237.
[0069]
1 and 3, reference numeral 254 denotes the first. of When the frame member 237 that does not use both the ND filters 238 and 239 is in the position shown in FIG. 1 with the leaf switch, it is pushed by the frame member 237 and turned on. Further, as shown in FIG. 3, when one ND filter 238 enters the optical path and stops at a position covering the opening 241, of Leaf switch 254 and the second shown in FIG. of The leaf switch 255 is in a non-contact state together with the frame member 237 and is turned off.
[0070]
Further, when the frame member 237 rotates to reach a position where the other filter 239 covers the opening 241, the second leaf switch 255 is turned on by being pushed by the frame member 237.
[0071]
That is, the first of Leaf switch 254 is on and second of Leaf switch 255 When is off, it indicates that the ND filter is not used. of Leaf switch 254 and second of When both leaf switches 255 are off, one of the lighter ND filters 238 is used. When the first leaf switch 254 is off and the second leaf switch 255 is on, the other ND filter is used. 239 is used.
[0072]
Now, assuming that the output shaft 232 of the meter 231 has rotated counterclockwise, the lever 233 also rotates in the direction of the arrow. With this movement, the frame member 237 rotates in the direction of the arrow around the rotation center 236 by interlocking with the long groove 235 and the pin 234.
[0073]
As a result, the ND filters 238 and 239 are inserted in the direction of the arrow in the optical path.
[0074]
FIG. 2 is a diagram showing an outline when the ND filter driving device shown in FIG. 1 is arranged in a zoom lens.
[0075]
Each of the lens groups 111 to 114 is shown in FIG. 12 It shows each group described in. Reference numeral 211 denotes a CCD, an aperture device (202, 203, 206) and an ND filter drive device (231, 237), both of which operate in a plane perpendicular to the optical axis 241. 3 shows one ND filter from the state shown in FIG. 238 Position that completely covers the open diameter Until The state which the frame member 237 rotated is shown.
[0076]
Needless to say, if the ND filter 239 is further rotated, the other ND filter 239 starts to reach the open diameter, and is finally covered.
[0077]
In the present embodiment, for example, one ND filter 238 sets the transmitted light amount to an open 1.5 stage (light amount 1 / 2.8), and the other ND filter 239 forms an open three stage (amount of light 1/8). By setting the density, the influence of shading can be greatly improved as compared with the case where the only ND filter having the same density as the other ND filter 239 is put into and out of the optical path.
[0078]
FIG. 4 shows a control block configuration diagram when the present invention is implemented. Figure 13 In these conventional devices shown in Can For the block configuration, the CPU 222 controls the operation of the actuator 231 for driving the ND filter (meter 231 in FIG. 1) via the ND meter driving circuit 241. 251 is an ND filter. 238, 239 As shown in Fig. 1. From the light path It is a switch that detects the state of complete disconnection. 261 is the other ND filter 239 In the light path A switch that turns on when fully engaged.
[0079]
FIG. 5 shows an exposure control method in this embodiment.
[0080]
Figure 5 In Leave The axis 242 indicates the shutter speed (CCD charge accumulation time). Here, the slowest shutter speed (point 245) is 1/60 seconds.
[0081]
An axis 243 indicates the aperture state. A point 245 is the aperture opening, and the aperture opening diameter becomes smaller (small aperture) in the direction extending to the lower left in the figure.
[0082]
A state where the shaft 244 enters the optical path of the ND filter is shown. On the way, “238IN” and “239IN” indicate positions where the filters of the respective densities (one filter 238 having a low density and the other filter 239 having a high density) completely cover the opening diameter at that time. . However The opening diameter at that time varies depending on the F value. Na The Here, in order to simplify the following description, F is defined as the smallest F value in a range where image degradation due to diffraction at the time of small aperture does not occur. _th This F _th For each aperture diameter obtained in Filters 238, 239 The position that covers " 238IN "and" 239IN ".
[0083]
On this graph, the point where the amount of transmitted light can be maximized (suitable for the darkest subject) is the point 245, and the ND filter is obtained when the aperture is fully opened and 1/60 seconds. 238, 239 But In the light path Not in. In addition ,point If proper exposure cannot be obtained even at 245, the Amp circuit 212 may perform amplification (gain increase) exceeding normal.
[0084]
In this figure, the exposure is controlled by moving on the bold line. However, this method of connecting the thick lines is not limited to this.
[0085]
First, from point 245, exposure control is performed by moving only the aperture. In the range indicated by points 245 to 246, the aperture is open to F. _th Be controlled between.
[0086]
F _th When the aperture is reduced as described above, image degradation occurs when the aperture is reduced as described above. To avoid this, the ND meter 231 is moved from point 246 to point 247 in order to reduce the amount of transmitted light. During this period, during section A, the ND filter idle period (ND filter) 238 Until the start of the effective light path.
[0087]
In order to avoid this idling, the line segment 249 may be set differently from the point 245 to the point 246 so as to connect the point 245 to the point 250. In this case, however, an ND filter is inserted. Since it is necessary to perform a certain position control, this point will be described in the following embodiments.
[0088]
Then, after reaching point 247, the shutter speed is increased to 1/250 seconds to reach point 248.
[0089]
6 and 7 are flowcharts showing the operation of the first embodiment.
[0090]
Step Start at 261. In step 263, it is checked whether the exposure is optimal. If not at the optimal exposure, step 264 detects overexposure or underexposure. . If over, go to step 265 , If it is under, step 269 in FIG. 7 is reached. If over, in step 265, the current F value is F _th Check if it is more open. If it is on the open side, it is between points 245 to 246 in FIG. Incidentally, in order to more surely confirm that it is within the range of points 245 to 246 in FIG. 5, the first ND-OUT state shown in FIG. of It may be confirmed that the leaf switch 254 is securely turned on.
[0091]
When the step 265 is N, the point 246 to 247, 247 to 248, and 248 to the small stop in FIG. Therefore, in step 267, the second NDIN switch. of The state of the leaf switch 255 is detected.
[0092]
ND filter 239 But In the light path If not, in step 268, the ND meter is driven to the IN side. If the ND filter has completely reached the other ND filter 239 having a high density, the determination in step 267 is Y, and in step 274, monitoring that the shutter speed does not exceed 1/250 second, In step 275, the shutter speed is increased.
[0093]
If proper exposure is not obtained even if the shutter reaches 1/250 sec in step 274, the aperture is further reduced in step 266 to obtain proper exposure even at the expense of image deterioration due to a small aperture.
[0094]
FIG. 7 shows a flowchart in the case of underexposure, and the flow of FIG. That is, in step 270, the current F value is F _th If it is determined that the aperture is closer to the open side, the aperture is driven further to the open side, and the flow returns to step 262 in FIG. The current F value is F _th In step 272, the second is determined. of Whether or not the leaf switch 255 is on is detected. If the leaf switch 255 is off, it is determined that the thinner ND filter 238 is present in the optical path, and the ND filter is evacuated from the optical path. Driving meter (Step 273) Figure 6 Steps 262 Return to.
[0095]
In step 272, the second of If it is determined that the leaf switch 255 is on, the other dark ND filter 239 is present in the optical path, and therefore it is determined in step 276 whether the shutter speed is greater than 1/60.
[0096]
If it is determined in step 276 that the shutter speed is 1/60, the aperture is driven to the open side in step 271 and the shutter time is set. 1/60 If it is determined that the shutter speed is not, the shutter time is decreased in step 277, and the process returns to step 262 in FIG.
[0097]
By the way, the thick line shown in FIG. 5 operates the means for limiting the amount of transmitted light in order of aperture, ND filter, shutter time, and aperture in order from the open, 1/60 sec, ND OUT state point 245. It may be changed based on the camera mode setting. In FIG. 4, the camera mode Sw219 reflects the intention to shoot such that the depth of field is as shallow as possible (for example, portrait mode), and in response to this, the order is as follows: shutter → ND filter → stop. To switch to.
[0098]
Note that the ND IN or OUT detection switch may be a photo interrupter or the like in addition to the leaf switch. Further, in the present embodiment, the ND filter that rotates as shown in FIGS. 1 and 3 is shown, but it may be configured to be slid.
[0099]
( For reference Second embodiment)
8 and 9 show the present invention. Reference in 2nd Embodiment of this is shown.
[0100]
For reference First of In the embodiment, the state where the ND filter is put in and out of the effective optical path is the second state where the ND filter 239 is IN as shown in FIG. of The state in which the ND filter 238 is OUT by the leaf switch 255 is only detected by the first leaf switch 254 as shown in FIG.
[0101]
The second embodiment is characterized by having an encoding means (ND encoder) capable of detecting the rotation angle of the ND filter as an absolute position.
[0102]
In FIG. 8, the block 228 As described above, an ND encoder for detecting the absolute position information of the ND meter is provided, and the detection result is taken into the CPU 222. In this case, in the CPU 222 memory In 223, various linkage relations between the ND meter and the aperture meter are stored, and the two meters can be linked based on the stored data.
[0103]
As this ND encoder, as well as a conventionally known diaphragm encoder means, in addition to a method of detecting a change in magnetic flux in the vicinity of the N pole / S pole boundary of the rotor magnet by a Hall element provided in a meter as an ND drive source, There are various methods such as a method in which the drive source is not a meter but a step motor drive and the drive input pulses from the reference position to the step motor are continuously counted.
[0104]
Such a configuration can be made by creating an interlocking state in the memory 223 so as to exclude the idle running section A in FIG.
[0105]
FIG. 9 shows some examples of such interlocking relationships. . The method of connecting the lines 249, 279, 280 and 281 from the point 245 is the same as in FIG. 5 of the first embodiment, and the light quantity control is performed from the point 245 using the aperture → ND filter → shutter → aperture. Is The same, but in the range of solid line 249, open → F _th ND to match each aperture diameter up to filter Can be made to stand by at a position as close as possible to the aperture diameter of the aperture as much as possible.
[0106]
Therefore, the “idle running section A” in FIG. 5 can be excluded.
[0107]
Also, the alternate long and short dash line 283 indicates that the shutter speed is [1/60], the aperture is open, and both the thin ND filter 238 and the dark ND filter 239 are retracted out of the optical path, and the shutter time is [1]. / 60], aperture value is F _th In this state, the dark ND filter 239 enters the optical path, that is, between the points 245 and 247, when both the diaphragm and the ND filter are interlocked with each other.
[0108]
Next, in the program indicated by the broken line, the ND filter is not allowed to enter the optical path for the purpose of obtaining a clean blur at the portion near the opening indicated by the reference numeral 284, and then the diaphragm and the ND filter are interlocked at the part indicated by the reference numeral 285. . In this case, the portion indicated by reference numeral 284 may be overlapped with the portion indicated by reference numeral 249.
[0109]
Further, the program indicated by the solid line 300 is a case in which the points 245 and 248 are directly connected so that the diaphragm and the ND filter are linked in a predetermined manner including the shutter time.
[0110]
These may be switched according to the mode state of the camera in accordance with the purpose and effect. In addition, F including the first embodiment _th The value itself may be changed as necessary. In addition, F _th The value of may be changed depending on the quality of the recording image quality.
(Third embodiment)
10 and 11 show a third embodiment.
[0111]
In the third embodiment, the ND filter driving mechanism is reduced in size compared to the first and second embodiments. As shown in FIG. 10, the ND filter 238 having a low concentration has an open diameter. The ND filter 239 having a larger density than the opening diameter 290 having an opening diameter smaller than the opening diameter 205 has an area covering the opening diameter 291 having an opening diameter smaller than the opening diameter 290.
[0112]
Therefore, according to the present embodiment, as apparent from FIG. 10, the rotation angle of the ND filter can be reduced. For this reason, in FIG. 10, although it is written with the same dimensions as those in FIGS.
[0113]
In FIG. 10, the ND filter 238 covers the opening diameter 290 and the ND filter 239 covers the opening diameter 291 (smaller than the opening diameter 290), but the ND filters 238 and 239 cover the same opening diameter 290. The ND filter 239 may be configured to cover an opening diameter (small aperture) smaller than the open diameter while the ND filter 238 covers the open diameter.
[0114]
As described in the first embodiment, the ND filter driving device may be slid without moving the ND filter about the rotation axis.
[0115]
FIG. 11 shows the interlocking relationship between the ND filter driving device and the diaphragm device shown in FIG.
[0116]
If the ND filter 238 is set to cover the stop F5.6 and the ND filter 239 is set to cover the stop F11, the stop and the ND filter are denoted by reference numerals 292, 293, 294, 295, and 296 as shown in FIG. It controls so that it may become the interlocking relationship shown in.
[0117]
Thereby, the trouble that the frame member of the ND filter covers the opening diameter is excluded. Further, as in the second embodiment, in order to exclude the “idle running section A”, the alternate long and short dash lines 297 and 298 may be used.
[0118]
Although the diaphragms in these embodiments are all shown as an example comprising two blades, it goes without saying that so-called iris diaphragms with five or more blades may be used.
[0119]
【The invention's effect】
As described above, according to the present invention, it is possible to ensure continuity of shooting and open blur while greatly improving the degree of vertical shading and the like by an ND filter without using a small aperture diffraction in an imaging apparatus using a CCD or the like. Taste can be ensured, and optimal exposure control according to the camera mode is achieved.
[0120]
Furthermore, the size can be reduced.
[Brief description of the drawings]
FIG. 1 shows the present invention. Reference in ND filter driving apparatus suitable for the first embodiment
[Figure 2] reference Schematic arrangement diagram in the zoom lens of the ND filter driving device of the first embodiment
[Fig. 3] reference The figure which shows the operation state of the ND filter drive device of 1st Embodiment of this
[Fig. 4] reference The block diagram of the ND filter drive device of 1st Embodiment of this
[Figure 5] reference Exposure compensation operation graph of the ND filter driving device of the first embodiment
[Fig. 6] reference Flowchart of the ND filter driving device of the first embodiment
[Fig. 7] reference Flowchart of the ND filter driving device of the first embodiment
FIG. 8 shows the present invention. Reference in Block diagram of the second embodiment
FIG. 9 reference Exposure compensation operation graph of the second embodiment
FIG. 10 shows an ND filter driving device suitable for the third embodiment of the present invention.
FIG. 11 is an exposure correction operation graph according to the third embodiment of the present invention.
FIG. 12 is a configuration diagram of a conventional zoom lens.
FIG. 13 is a block diagram relating to exposure control of a conventional imaging apparatus.
FIG. 14 is a diagram of the relationship between the diaphragm and the MTF.
FIG. 15 shows a conventional example of aperture and ND.
FIG. 16 shows a conventional example of exposure control using a combination of an aperture and a shutter.
[Explanation of symbols]
231 ND drive source
205 Opening diameter
238 ND filter
239 ND filter with higher density than ND filter 238
222 CPU
223 Memory of ND and diaphragm interlocking relationship
278 ND encoder

Claims (1)

The first drive means drives a plurality of light quantity adjustment members to make the aperture diameter variable, and the second drive means is driven to be able to enter and leave the effective optical path within a plane substantially perpendicular to the optical axis. a ND filter that, the light amount adjustment state detecting means for detecting a light amount adjustment state by the light amount adjustment member, a position detecting means for detecting a position of the ND filter for inside and outside of the effective optical path, the detection of the light amount adjustment state detecting means based on the detection information of the information and said position detecting means, a light amount adjusting device and a control means for controlling driving of the first driving means and the second driving means,
The ND filter, when entering from the effective optical path outside to the effective optical path, initially the the first ND filter area to be effective optical path, lower transmittance than the first ND filter area, and A second ND filter region having a small area,
The control means includes
While the light amount adjustment state detected by the light amount adjustment state detection means is from the first opening diameter to the second opening diameter smaller than the first opening diameter, the second driving means is driven. Covering the opening formed by the light amount adjusting member with the first ND filter region by allowing the first ND filter region to enter the effective optical path,
When the light amount adjustment state detected by the light amount adjustment state detection means changes to the smaller diameter side than the second opening diameter, the second drive means is further driven in the same direction to A light amount adjusting apparatus , wherein an opening formed by the light amount adjusting member is covered with the second ND filter region by allowing an ND filter region to enter the effective optical path .

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