JP7339792B2 - Lens device and imaging device - Google Patents

Description

The present invention relates to a lens device and an imaging device.

If the lens device is of a replaceable type that can be separated from the main body of the imaging device, the flange back may slightly deviate from the design value due to manufacturing errors in the components and variations in the characteristics of the optical elements. When the flange focal length shifts, the focus shift may occur in the zoom lens when the focal length is changed from the telephoto side to the wide-angle side. When shooting moving images, defocusing caused by zooming can be a hindrance. Such a lens device has a mechanism that adjusts the flange back by moving some optical elements in the direction of the optical axis.

Japanese Patent Laid-Open No. 2004-100000 discloses a lens device that connects an annular operation member and a rotation-to-linear motion conversion mechanism such as a multi-threaded screw with a connection pin, and rotates the operation member to move an optical element and adjust the flange focal distance. disclosed.

JP 2006-235418 A

When the combination of the lens device and the main body of the imaging device is the same, once the flange back is adjusted, shooting can be performed without repeating the adjustment. However, in the lens apparatus, when the conditions of the shooting environment, such as temperature, humidity, and atmospheric pressure, change significantly, the back focus changes due to changes in the dimensions of components including optical elements and changes in the refractive index of air. Therefore, there is a possibility of overlooking the change in the back focus that occurs after adjusting the flange back only by looking through the small viewfinder. In other words, shooting may be wasted. SUMMARY OF THE INVENTION It is an object of the present invention to provide, for example, a lens device that is advantageous in reducing back focus deviation.

In order to achieve the above object, the lens apparatus of the present invention comprises an optical element that changes the focal length, an adjustment section that adjusts the flange back, and a detection section that detects a first environmental condition that changes the flange back. and the adjusting unit based on the difference between the second environmental condition and the first environmental condition when the flange focal length is adjusted by the adjusting unit , and the threshold set based on the focal length. and a processing unit that generates a signal for prompting adjustment of the flange back.

According to the present invention, for example, it is possible to provide a lens device that is advantageous in reducing back focus deviation.

Schematic diagram of the configuration of the lens device according to the first embodiment 4 is a flow chart of processing of the lens device in the first embodiment Schematic diagram of the configuration of the lens device according to the second embodiment Flowchart of processing of the lens device in the second embodiment

BEST MODE FOR CARRYING OUT THE INVENTION Preferred embodiments of the present invention will be described below based on examples shown in FIGS.

FIG. 1 is a schematic diagram of the configuration of a first embodiment of a lens device to which the present invention is applied.
A lens device 101 includes a plurality of lens groups 2 and a lens barrel 3 housing the lens groups 2 . When the lens device 101 is attached to the imaging device, the lens group 21 closest to the imaging device in the lens group 2 is an imaging optical system, and the back focus of the lens device 101 is adjusted by moving in the optical axis direction. can be changed. A lens barrel accommodating a lens group 21 of this imaging optical system is connected to a flange back adjustment mechanism (adjustment unit) 4 having a multi-screw structure (not shown), and the position in the optical axis direction is adjusted by manual operation. be able to. The flange focal length adjustment mechanism 4 is provided with a mode detection switch 5 so that the detected value is turned ON at the start of manual operation for adjusting the flange focal length, and is turned OFF at the end of the adjustment operation. is configured to

The lens device 101 is provided with a temperature sensor (detection section) 6 as a detection means for detecting the temperature inside the lens device. Storage means (storage unit) 71 for storing the detected value of the temperature sensor 6, and calculation means (processing unit) for calculating the amount of back focus change from the detected value of the temperature sensor 6 and the stored value stored in the storage means 71. part) 81 . Further, the lens device 101 is provided with an LED indicator (display unit) 9 as display means for visually displaying the degree of change in back focus.

The flow of data exchange in the lens apparatus of this embodiment will be described with reference to the flow chart of FIG.

First, when the lens device 101 is attached to the imaging device and the power is turned on (S201), the value of the adjustment temperature _T1 stored in the storage means 71 is read out to the calculation means 81 (S202). It should be noted that the temperature during adjustment (detected value during adjustment) _T1 of the storage means 71 at this time holds the value stored when the lens apparatus was used last time.

Next, the calculation means 81 acquires the detected value of the temperature sensor 6 at that time (S203). The detected value of the temperature sensor 6 at this time is assumed to be _T0 .

Next, the calculation means 81 acquires the detection value of the mode detection switch 5 of the flange focal length adjustment mechanism 4 (S204). When the detection value of the mode detection switch 5 is ON, the detection value _T0 of the temperature sensor 6 is sent to the storage means 71, and the value of the adjustment temperature T1 stored in the storage means ₇₁ is updated to _T0 . (S205). After updating the value in the storage unit 71, the process returns to the process of acquiring the detection value of the temperature sensor 6 (S203).

On the other hand, if the detected value of the mode detection switch 5 is OFF, the environmental temperature _T2 is set to _T0 (S206). Subsequently, the adjustment temperature _T1 is acquired from the storage means 71, and the back focus change amount ΔBf caused by the environmental temperature change after the flange back adjustment is calculated from the temperature difference between the environmental temperature _T2 and the adjustment temperature _T1 (S207). . Here, in calculating the amount of change in back focus ΔBf, a method of obtaining by approximate calculation based on the measured data table of the amount of change in back focus with respect to temperature change is used.

Next, the level of the amount of defocus is ranked and determined from the calculated back focus change amount ΔBf (S208). Also, a display signal to be sent to the display means is generated according to the determined rank (S209). In this embodiment, the amount of defocus is classified into three ranks of A, B, and C. FIG.

Rank A corresponds to a level at which the amount of change in back focus ΔBf is small and defocus cannot be visually determined from the captured image. At this time, the LED indicator 9 generates a display signal for non-lighting. Rank C corresponds to a level at which the amount of back focus change ΔBf is large, and defocus can be visually determined from the captured image even when the pixel pitch of the imaging element of the imaging apparatus is coarse. At this time, the LED indicator 9 generates a display signal that lights up in red.

Rank B has a back focus change amount ΔBf that is intermediate between Rank A and Rank C, and if the pixel pitch of the image pickup device of the image pickup device is fine, the defocus can be visually determined from the captured image. If it is rough, it corresponds to a level that cannot be visually distinguished. At this time, the LED indicator 9 generates a display signal that lights up in blue. Let the amount of change in the back focus at the boundary between rank A and rank B be an allowable value (threshold) Bf _AB , and let the amount of change in the back focus at the boundary between rank B and rank C be an allowable value (threshold) Bf _BC .

The display signal generated by the calculation means is sent to the LED indicator 9, which is the display means, and the display contents are updated (S210). After the display content is updated, the process returns to the process of acquiring the detection value of the temperature sensor 6 (S203), and the process of the above-described flow is repeatedly executed until the power of the imaging device is turned off (S211). .

The behavior of the above-described lens device during use will be described below.
Immediately after mounting the lens device 101 on the imaging apparatus and performing flange back adjustment, or in a state where flange back adjustment is performed once under the same temperature condition and the power is turned on again, there is no deviation in flange back. The LED indicator 9 is off.

As the ambient temperature rises or falls from the temperature at which the flange back adjustment is performed, the amount of change in the back focus of the lens device 101 increases as the temperature changes. As the temperature change increases, the LED indicator 9 lights blue at a certain point. At this time, the back focus change amount ΔBf is expected to be greater than or equal to Bf _AB and less than Bf _BC . In other words, when using an image pickup device with a fine pixel pitch of the image pickup device, this indicates that the flange back adjustment should be performed again.

The display of the LED indicator 9 allows the photographer to easily notice that the flange focal length has shifted. If the flange focal length adjustment is performed at this stage, the temperature difference between the ambient temperature _T2 and the adjusted temperature _T1 becomes 0, so the back focus change amount ΔBf also becomes 0, and the LED indicator 9 turns off. be changed. Note that even when the LED indicator 9 is lit in blue, it can be said that the flange back adjustment is not necessary when using an imaging device with a rough pixel pitch of the imaging device.

On the other hand, when the temperature change increases further from the state where the LED indicator 9 is lit in blue, the LED indicator 9 is lit in red at a certain point. At this time, the back focus change amount ΔBf is expected to be greater than or equal to Bf _BC . In other words, regardless of whether the pixel pitch of the imaging element of the imaging apparatus is fine or coarse, it indicates that the flange back adjustment should be performed again in any case. The display of the LED indicator 9 makes it easy for the photographer to notice that the flange back is displaced.

As described above, according to the lens apparatus of the present embodiment, when the temperature environment changes significantly and the back focus changes, the content displayed on the display means is changed, so that the flange back adjustment can be performed again. A photographer can easily notice the necessity. As a result, it is possible to prevent the user from failing to obtain an image of desired image quality due to a lack of awareness of the occurrence of defocus due to a change in back focus at the time of photographing, and from wasting the photographing opportunity.

Further, when the lens device is mounted on two types of image pickup devices having different pixel pitches of image pickup elements, such as an HD-compatible image pickup device and a 4K-compatible image pickup device, the display signal is divided into three stages as in the present embodiment. Therefore, it is possible to judge whether or not to adjust the flange back according to the type.

In this embodiment, the temperature sensor 6 is provided as detecting means for detecting a change in shooting environment conditions that affect the back focus of the lens apparatus, but the detecting means applicable to the present invention is not limited to this. . Since the back focus of the lens apparatus also changes due to significant changes in humidity and air pressure, the detection means may be a sensor that detects changes in humidity or air pressure. Moreover, it is good also as a structure provided with at least one of the detection means of multiple types regarding these.

Furthermore, in the above-described embodiment, the LED indicator 9 is provided as a display means in the lens device, but a display or the like provided in the lens device or a driving device attached to the lens device may be used. The present invention may also be applied to a mode in which the display means is a viewfinder provided in the imaging device, and the display contents of the viewfinder are changed by transmitting a display signal generated by the lens device to the imaging device (external device). can be applied.

FIG. 3 is a schematic diagram of the configuration of the second embodiment of the lens apparatus to which the present invention is applied, and the same reference numerals as in the first embodiment indicate the same components. The points of configuration different from the first embodiment will be described below.

A lens group 22 adjacent to the object side of the lens group 21 of the imaging optical system of the lens device 102 is a magnification conversion optical system (an optical element that changes the focal length). A lens barrel housing a lens group 22 of the magnification conversion optical system is connected to a magnification conversion mechanism 10 that can be switched (inserted and removed) between insertion and retraction into the optical path, and the magnification of the lens device can be set in two stages by manual operation. You can switch (shift the focal length range). The magnification conversion mechanism 10 is provided with an insertion detection switch 11, and is configured so that the detection value is turned ON when the magnification conversion optical system is inserted into the optical axis, and the detection value is turned OFF when the magnification conversion optical system is retracted from the optical axis. ing.

The lens device 102 has an air pressure sensor 12 as detecting means for detecting the internal air pressure. Also provided are storage means 72 for storing the detection value of the atmospheric pressure sensor 12 and calculation means 82 for calculating the amount of change in the back focus from the detection value of the atmospheric pressure sensor 12 and the stored value stored in the storage means 72 . Further, the lens device 102 is provided with a display (display unit) 13 .

The flow of data transfer in the lens apparatus of this embodiment will be described with reference to the flow chart of FIG.

First, when the lens device 102 is attached to the imaging device and the power is turned on (S301), the value of the adjusted air pressure _P1 stored in the storage means 72 is read out to the calculation means 82 (S302). At this time, the value stored when the lens apparatus was used last time is held in the adjustment time air pressure _P1 of the storage means 72 .

Next, the calculation means 82 acquires the detection value of the atmospheric pressure sensor 12 at that time (S303). The detected value of the atmospheric pressure sensor 12 at this time is assumed to be _P0 .

Next, the calculation means 82 acquires the detection value of the mode detection switch 5 of the flange focal length adjustment mechanism 4 (S304). Here, when the detection value of the mode detection switch 5 is ON, the detection value _P0 of the atmospheric pressure sensor 12 is sent to the storage means 72, and the value of the adjusted atmospheric pressure _P1 stored in the storage means 72 becomes _P0. (S305). After updating the value of the storage unit 72, the process returns to the process of acquiring the detection value of the atmospheric pressure sensor 12 (S303).

On the other hand, if the value detected by the mode detection switch 5 is OFF, the value of the environmental air pressure _P2 is set to _P0 (S306). Subsequently, the adjustment air pressure _P1 is obtained from the storage means 72, and the back focus change amount ΔBf caused by the air pressure change after the flange back adjustment is calculated from the air pressure difference between the ambient air pressure _P2 and the adjustment air pressure _P1 (S307). Here, in calculating the back focus change amount ΔBf, a method of obtaining by approximate calculation based on an actual measurement data table of the back focus change amount with respect to atmospheric pressure change is used.

Next, the level of the defocus amount is ranked and determined from the calculated back focus change amount ΔBf (S308). In this embodiment, the amount of defocus is classified into three ranks of D, E, and F.

Rank D corresponds to a level at which the amount of change in back focus ΔBf is small and defocus cannot be visually determined from the captured image. Rank F corresponds to a level at which the amount of back focus change ΔBf is large, and out of focus can be visually determined from a captured image even when the magnification conversion optical system is retracted from the optical axis and the optical magnification of the lens device is low. Rank E corresponds to the fact that the amount of back focus change ΔBf is intermediate between the ranks D and F described above.

That is, when the magnification conversion optical system is inserted into the optical path and the optical magnification of the lens device is high, the defocus can be determined visually from the photographed image. corresponds to a level that cannot be visually distinguished. The amount of change in the back focus at the boundary between the ranks D and E is defined as an allowable value (threshold) Bf _DE , and the amount of change in the back focus at the boundary between the ranks E and F is defined as an allowable value (threshold) Bf _EF .

Subsequently, the calculation means 82 acquires the detection value of the insertion detection switch 11 of the magnification conversion mechanism 10 (S309). A display signal to be sent to the display means is generated according to the value of the insertion detection switch 11 and the rank obtained by judging the defocus amount as described above (S310). The details of display signal generation will be described below.

If the determination of the defocus amount is rank D, a display signal is generated to hide the display on the display 13 . Also when the determination of the defocus amount is rank E and the detection value of the insertion detection switch 11 is OFF, a display signal is generated to hide the display on the display 13 .

On the other hand, when the determination of the defocus amount is rank E and the detection value of the insertion detection switch 11 is ON, the display 13 displays "FLANGE BACK ERROR dBf: ◯◯◯".
to generate a display signal. The above ◯◯◯ indicates that the value of the calculated back focus change amount ΔBf is displayed. It is also assumed that a similar display signal is generated when the determination of the defocus amount is rank F.

The display signal generated by the computing means is sent to the display 13, which is the display means, and the display contents are updated (S311). After the display content is updated, the process returns to the process of acquiring the detection value of the air pressure sensor 12 (S303), and the process of the above flow is repeatedly executed until the power of the imaging device is turned off (S312). .

The behavior of the above-described lens device during use will be described below.
Immediately after the lens device 102 is attached to the imaging apparatus and the flange back adjustment is performed, or when the power is turned on again after the flange back adjustment is performed under the same air pressure condition, there is no deviation of the flange back. The display 13 is not displayed.

When the air pressure in the shooting environment rises or falls from the conditions under which the flange back adjustment is performed, the amount of change in the back focus of the lens device 102 increases with the change in air pressure. As the air pressure change increases, at a certain point, the display 13 shows "FLANGE BACK ERROR dBf: ○○○".
is displayed. The display on the display 13 allows the photographer to easily notice the fact that the flange focal length has shifted.

If the flange back adjustment is performed at this stage, the pressure difference between the ambient pressure _P2 and the adjustment pressure _P1 becomes 0, so the back focus change amount ΔBf also becomes 0, and the display 13 disappears. be changed. When adjusting the flange focal distance, referring to the numerical values in the XX section displayed on the display 13 enables the adjustment work to be performed more efficiently.

When the back focus change amount ΔBf is expected to be greater than or equal to Bf _DE and less than Bf _EF , if the magnification conversion optical system is retracted from the optical path, the display 13 is not displayed, and the magnification conversion optical system is inserted into the optical path. , and the above error information is displayed on the display 13 . In this state, flange focal length adjustment is necessary only when photographing is performed under conditions of high optical magnification with the magnification conversion optical system inserted in the optical path. That is, when error information is displayed on the display 13 under the photographing conditions, the photographer should adjust the flange focal distance.

As described above, according to the lens apparatus of this embodiment, when the air pressure changes significantly and the back focus changes, the content displayed on the display means is changed, so that it is necessary to adjust the flange back again. The photographer can easily notice the nature. As a result, it is possible to prevent the user from failing to obtain an image of desired image quality due to a lack of awareness of the occurrence of defocus due to a change in back focus at the time of photographing, and from wasting the photographing opportunity.

In addition, when the focal length of the lens device can be selected stepwise as in this embodiment having a magnification conversion optical system, the amount of back focus fluctuation can be determined with a different allowable value according to the focal length at the time of photographing. Opportunities requiring flange back adjustment can be more appropriately limited.

When the amount of change in the back focus is displayed on the display 13 as in the present embodiment, it is possible to provide an indication of which direction and how much movement should be made when adjusting the flange back focal length. It can be carried out. In this embodiment, the back focus variation amount is displayed as it is, but a scale is provided in the manual operation portion of the flange back adjustment mechanism so that the number of scales of the amount to be adjusted (adjustment amount) is displayed. can be By doing so, it becomes possible to easily correct the deviation of the flange back even when it is not possible to set an appropriate subject necessary for performing normal flange back adjustment.

In this embodiment, the atmospheric pressure sensor 12 is provided as detecting means for detecting a change in shooting environment conditions that affect the back focus of the lens apparatus, but the detecting means applicable to the present invention is not limited to this. . The detection means may be a sensor that detects changes in temperature or changes in humidity. Moreover, it is good also as a structure provided with the detection means of multiple types regarding these.
Further, by constructing an imaging apparatus having the lens apparatus of the present invention and an imaging element for receiving an image formed by the lens apparatus, an imaging apparatus having the effects of the present invention can be realized.

Although preferred embodiments of the present invention have been described above, the present invention is not limited to these embodiments, and various modifications and changes are possible within the scope of the gist.

101, 102: Lens device 6: Temperature sensor (detector)
12: Air pressure sensor (detection part)
71, 72: Storage units 81, 82: Calculation units

Claims (9)

an optical element that changes the focal length;
an adjustment unit that adjusts the flange back;
a detection unit that detects a first environmental condition that changes the flange back;
Based on the difference between the second environmental condition and the first environmental condition when the flange back is adjusted by the adjusting unit, and the threshold value set based on the focal length , the flange back is adjusted by the adjusting unit. a processing unit that generates a signal to prompt adjustment of the back;
A lens device comprising: 2. The lens apparatus of claim 1, wherein said first and second environmental conditions include at least one of temperature, humidity and atmospheric pressure. 3. The lens device according to claim 1, wherein a plurality of said signals different from each other are generated based on said difference and a plurality of threshold values. 4. The lens device according to claim 3, wherein the plurality of different signals include three types of signals. 5. The lens device according to claim 3, wherein the plurality of signals are signals for displaying different contents on a display unit based on the signals . 6. The lens device according to any one of claims 1 to 5, wherein the optical element can be inserted into and removed from the optical path. 7. The lens device according to any one of claims 1 to 6 , wherein the signal indicates an adjustment amount of the flange focal length by the adjusting section. 8. The lens device according to claim 1 , further comprising a display section for displaying information based on said signal. a lens device according to any one of claims 1 to 8 ;
an imaging device that receives an image formed by the lens device;
An imaging device characterized by comprising:

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