Lens barrel

Abstract

To provide a lens barrel which enables adjustment of how flare and ghost images appear, including switching of appearance, according to the needs of a photographer while maintaining flare and ghost resistance.SOLUTION: A lens barrel with multiple lenses and an aperture stop for adjusting the amount of incident light is provided, the lens barrel comprising an optical member capable of moving independently of focusing and zooming movements inside the lens barrel, and an operating member for moving the optical member.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to a lens barrel that is detachably attached to an image pickup device. [Background technology]

[0002] It is known that when shooting, incident light can be unintentionally reflected or scattered inside the lens barrel, appearing as flare or ghosting in the captured image.

[0003] Conventionally, it has been considered undesirable for flare and ghosting to appear in captured images, so when designing a lens barrel, measures have been taken to prevent the generation of stray light, such as reflection and scattering, inside the lens barrel, which can cause flare and ghosting.

[0004] However, in recent years, when shooting video with an imaging device, there is a demand to intentionally generate flare and ghosting during shooting as one of the classical video expressions.

[0005] Patent Document 1 discloses an imaging lens that is capable of changing the occurrence state of flare, which is an optical aberration, by moving the position of a light blocking member at the tip of the imaging lens in the optical axis direction. [Prior art documents] [Patent documents]

[0006] [Patent Document 1] JP 2022-114327 A Summary of the Invention [Problem to be solved by the invention]

[0007] However, while the imaging lens described in Patent Document 1 can achieve an effect similar to that of a soft focus lens by changing the conditions under which flare occurs, it has a problem in that the sense of resolution on the focal plane is impaired.

[0008] The present invention has been made in consideration of the above circumstances, and aims to provide a lens barrel that is capable of adjusting the appearance of flare and ghosting, including switching the appearance, in accordance with the photographer's wishes while maintaining resistance to flare and ghosting. [Means for solving the problem]

[0009] A first invention, which is a means for solving the above problems, is a lens barrel having a plurality of lenses and an aperture that adjusts the amount of incident light, characterized in that the lens barrel is provided with an optical member that can move within the lens barrel independently of focusing and magnification changing operations, and an operating member that moves the optical member. Effect of the Invention

[0010] According to the present invention, it is possible to provide a lens barrel that is capable of adjusting the appearance of flare and ghosting, including switching the appearance, in accordance with the photographer's wishes while maintaining resistance to flare and ghosting. [Brief description of the drawings]

[0011] [Figure 1] 1 is a cross-sectional view of a lens barrel according to a first embodiment of the present invention; [Diagram 2] 1 is a cross-sectional view of a lens barrel according to a first embodiment of the present invention; [Diagram 3] FIG. 6 is an enlarged view of an optical member according to a second embodiment of the present invention. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0012] Hereinafter, the best mode for carrying out the present invention will be described with reference to the accompanying drawings. However, the present invention is not limited to the embodiment.

[0013] 1 and 2 are cross-sectional views of a lens barrel 1 according to an embodiment of the present invention. Specifically, the cross-sectional views are from the vicinity of the aperture 10 of the lens barrel 1 of the present invention through a mount that engages with an imaging device (not shown) to the image plane that is the focal plane of the incident light, that is, to the imaging element of the imaging device. In each figure, the left side is the subject side, and the right side is the image plane side. Next, the light rays in each figure will be explained. The thick line is the light that is incident at 100% of the image height, and the thin line is the light that is incident at 70% of the image height. In addition, the line diffusing from the optical member 11 in FIG. 2 to the image side is scattered light. The optical axis of the lens barrel 1 is not shown in FIG. 1 and FIG. 2. However, the horizontal line passing through the vicinity of the center of the lens including the optical element 20 in the figure is the optical axis of the lens barrel 1. In addition, the horizontal direction in the figure is the optical axis direction, and the up and down directions are the radial direction.

[0014] Fig. 1 shows the lens barrel 1 in a state where the optical member 11 is not in contact with incident light, and Fig. 2 shows the lens barrel 1 in a state where the optical member 11 is moved toward the image sensor I by operating the operation unit, causing it to come into contact with incident light and generate scattered light. For reference, incident light that does not come into contact with the optical member 11 in Fig. 1 travels straight ahead and is reflected inside the lens barrel, but by applying commonly known anti-ghosting measures inside the lens barrel 1, the lens barrel 1 itself is resistant to ghosting.

[0015] The configuration of a lens barrel 1 according to a first embodiment of the present invention will be described with reference to FIG.

[0016] The lens barrel 1 is attached to an imaging device (not shown) via a mount, and having a mount that can be engaged with the mount on the imaging device makes the lens barrel 1 replaceable. The lens barrel 1 in Fig. 1 also has multiple lenses inside the object side (not shown), and some of the lenses move along the optical axis to achieve the focusing and magnification functions of the lens barrel 1.

[0017] In addition to the optical elements, the lens barrel 1 contains an aperture 10 inside, and an optical member 11 on the image side of the aperture 10 .

[0018] The diaphragm 10 narrows the light that enters the lens barrel 1, thereby adjusting the amount of light that enters the image sensor I. The diaphragm 10 has multiple arc-shaped diaphragm blades and an aperture, and the diaphragm blades that make up the diaphragm 10 are driven and the opening area changes when the photographer operates a control signal sent from the CPU of the imaging device or an diaphragm ring that is located on the outer diameter of the lens barrel 1. As a result, the amount of incident light that passes through the diaphragm 10 is adjusted.

[0019] The optical member 11 can move along the optical axis, and by contacting the upper rays of the 100% image height ray and the 70% image height ray shown in FIG. 1 and FIG. 2, the scattered light shown in FIG. 2, which is stray light, is generated. When the generated scattered light reaches the image sensor I, it appears as flare or ghost in the captured image including the video. For this reason, it is desirable that the optical member 11 has a reflectance of 2% or more. Note that the inner diameter part of the optical member 11 that contacts the above-mentioned upper rays needs to have a certain thickness in the optical axis direction, and is a surface parallel to the optical axis. If there is no thickness, the scattering area and illuminance of the flare or ghost that appears in the captured image may be small, and the expected effect may not be obtained. The specific thickness will be described later. Also, the optical member 11 can move independently of the focusing or magnification operation (independently of each other).

[0020] For reference, stray light is generated due to reflections that are not intended in the design inside the lens barrel 1. As a countermeasure against stray light in the lens barrel 1, a flocked sheet is sometimes attached to the inner surface of the lens barrel 1 as an anti-reflection measure. This flocked sheet has a low reflectance of about 1%, so by attaching it to the location inside the lens barrel 1 where reflections occur, it becomes possible to prevent unintended reflections. Therefore, in the present invention, which intentionally generates reflections inside the lens barrel 1, it is desirable for the reflectance of the optical members that generate scattered light from incident light to be 2% or more.

[0021] The optical member 11 moves along the optical axis when the photographer operates a ring (operation unit, not shown) similar to a focus ring or manual ring arranged on the outer diameter of the lens barrel 1. The movable range of the optical member 11 is from a position where it does not come into contact with the incident light as shown in Fig. 1 to a position where it comes into contact with the upper ray of the 100% image height ray as described above, and moves along the optical axis to the image side to come into contact with the upper ray of the 70% image height ray. It is also possible to make the optical member 11 movable further toward the image side in order to change the degree of contact with the incident light depending on the degree of flare or ghosting that is desired to appear in the captured image.

[0022] The aperture 10 of the lens barrel 1 shown in Figures 1 and 2 is in an open state. Therefore, the 70% image height ray and the 100% image height ray shown in Figures 1 and 2 also pass through the aperture 10 in the open state. Here, if it is desired to make flare or ghost appear in the captured image even when the aperture 10 is stopped down, this can be achieved by changing the movable range of the optical member 11 according to the state of incident light at each f-stop value of the aperture 10. Furthermore, in the case where the focal length changes as in a zoom lens, this can also be achieved by changing the movable range of the optical member 11 according to the state of incident light at each focal length.

[0023] Also, in this embodiment, while the optical member 11 contacts the upper rays of the 100% image height ray through the 70% image height ray in that order from the outer diameter side of the lens barrel 1 toward the optical axis, depending on the optical design of the lens barrel 1, incident light of a lower image height than the 70% image height ray may contact the optical member 11. When the present invention is applied to a lens barrel 1 having such an optical design, it is possible to change the range of ray heights at which flare or ghosting occurs by changing the movable range of the optical member 11 as described above.

[0024] The portion of the optical member 11 that comes into contact with the incident light has a certain thickness in the optical axis direction. Specifically, a thickness of about 0.1 mm to 4.0 mm is desirable. If the thickness is less than this, a situation may occur in which the optical member 11 does not come into contact with 70% of the image height light rays at a position where the optical member 11 comes into contact with 100% of the image height light rays, and the amount of movement of the optical member 11 increases. Furthermore, if the optical member 11 is thicker than this, the optical member 11 becomes too large and it becomes difficult to hide it in a position where it does not come into contact with the incident light.

[0025] Furthermore, as described above, by appropriately adjusting the thickness of optical member 11 along with changing the movable range of optical member 11, it is possible to adjust the state of contact between lens barrel 1 and incident light.

[0026] Furthermore, the optical member 11 is disposed on the image plane side of the aperture 10 of the lens barrel 1. As described above, if flare or ghosting is to be prevented from appearing in the captured image, it is necessary to hide the optical member 11 in a position where it does not come into contact with the incident light. In this case, the periphery of the aperture 10 is narrowed down as the rays of the incident light pass through the aperture 10, so it is possible to avoid contact with the incident light by making the radial size of the optical member 11 slightly larger than that of the aperture 10. Therefore, it is preferable to dispose the optical member 11 near the aperture 10. Also, disposing the optical member 11 on the imaging element I side of the aperture 10 as shown in FIG. 1 is often easier than the object side in terms of optical design in terms of ensuring the movable range of the optical member 11 in the optical axis direction.

[0027] In addition, by disposing the optical element 20 between the optical member 11 and the aperture 10, the light beam narrowed down when passing through the aperture 10 is refracted by the optical element 20 toward the outer diameter side of the lens barrel 1 like the 70% image height ray and the 100% image height ray shown in Figs. 1 and 2, and the distance from the aperture 10 is shortened because the optical member 11 comes into contact with the 70% image height ray and the 100% image height ray. Alternatively, the movable range of the optical member 11 required to change the degree of contact with the 70% image height ray and the 100% image height ray is shortened. The above effects are obtained.

[0028] In Example 1 shown in Figs. 1 and 2, an optical element 20 is disposed between the aperture 10 and the optical member 11. The optical element 20 is composed of a biconcave lens, or a cemented lens composed of a biconcave lens and a biconvex lens. However, the optical element 20 is not limited to a plurality of lenses, and may be composed of a single lens. Note that the optical element 20 shown in Fig. 3 is a part of the cemented lens shown in Figs. 1 and 2. The optical element 20 is fixed inside the lens barrel 1 by a presser 21.

[0029] As an example, the following describes a case where the present invention is applied to the optical system described in Example 1 of Japanese Patent No. 5952167. Note that the state of the optical system is the wide-angle end and the aperture 10 is fully open.

[0030] When the thickness of the optical member 11 in the optical axis direction is 0.2 mm, a ghost occurs for a light source with 100% of the angle of view when the movement amount of the optical member 11 in the optical axis direction is 2.4 mm, and no ghost occurs for a light source with 70% of the angle of view up to a movement amount of 4.5 mm. Next, when the movement amount is 4.5 mm or more, a ghost occurs for a light source with 70% to 100% of the angle of view.

[0031] In addition, when the thickness of the optical member 11 in the optical axis direction is 1.0 mm, a ghost occurs for a light source with a 100% angle of view when the movement amount of the optical member 11 in the optical axis direction is 1.7 mm, and no ghost occurs for a light source with a 70% angle of view when the movement amount is up to 3.8 mm.

[0032] The amount of movement of the optical member 11 indicates the distance moved from a reference point that is 14.04 mm away from the aperture 10 toward the image side in the optical axis direction.

[0033] 3 is an enlarged view of the periphery of the optical element 20, the presser 21, and the optical member 11 located above the optical axis from the cross-sectional views of Example 1 shown in Figures 1 and 2. The straight line extending from the lower left to the center in the figure indicates incident light.

[0034] Next, the optical member 11 described above is a member having a reflectance of 2% or more, and in the first embodiment described in FIG. 1 and FIG. 2, the optical member 11 is movable in the optical axis direction by operating the operation unit. On the other hand, in the configuration of the second embodiment of the present application, as shown in FIG. 3, the optical member 11 is composed of a light shielding member 111 and a glossy member 112 in order from the object side. In this case, the glossy member 112 is fixed, and the light shielding member 111 moves between the light shielding member 111 shown by the dotted line and the light shielding member 111 shown by the solid line by operating the operation unit. That is, a part of the optical member 11 of the second embodiment is movable in the direction along the optical axis. Also, in the configuration of the optical member of the second embodiment, the glossy member 112 has a reflectance of 2% or more.

[0035] Also, the light shielding member 111 is located between the diaphragm 10 and the glossy member 112. In this configuration, the light shielding member 111 moves to switch whether or not contact with the incident light occurs. When the light shielding member 111 is located at a non-contact position (light shielding member 111 shown by dotted lines in FIG. 3), the incident light extending from the lower left reaches the glossy member 112 without being blocked by the light shielding member 111, and is reflected by the glossy member 112 to generate scattered light as shown by the dashed line. As a result, flare and ghosts are generated in the captured image, similar to the scattered light shown on the image side of the optical member 11 in FIG. 2 showing the first embodiment. On the other hand, when the light shielding member 111 is located at a contact position (light shielding member shown by solid lines in FIG. 3), the incident light is shielded by the light shielding member 111. Therefore, the incident light does not reach the glossy member 112, so no scattered light is generated due to contact with the glossy member 112, and no ghost or flare appears in the captured image.

[0036] Next, comparing the configuration of the optical member 11 of the first embodiment with the optical member 11 of the second embodiment, which is made up of the light shielding member 111 and the glossy member 112, it is possible to shorten the movable range of the light shielding member 111 by ensuring that the reflection surface of the glossy member 112, which reflects the incident light, is long in the optical axis direction. In addition, the light shielding member 111 does not need to be thick in the optical axis direction, as long as it is in contact with the incident light. Therefore, the light shielding member 111 may be a sheet that can block light. In addition, it is easy to contact the light rays on the inner diameter side. As a result, the configuration of the optical member 11 made up of the glossy member 112 and the light shielding member 111, which is more space-saving than the configuration of the optical member 11 of the first embodiment, can obtain the same effect.

[0037] Furthermore, the optical member 11 of the first and second embodiments described above controls contact with the incident light by moving in the optical axis direction. On the other hand, the optical member 11 may be movable in the radial direction. Specifically, the optical member 11 has a configuration similar to that of the diaphragm 10, and the photographer operates an operation unit arranged on the outer diameter of the lens barrel 1 in the same manner as an aperture ring used in a commonly known lens barrel 1, and the multiple arc-shaped members constituting the optical member 11 move from an open state to a closed state, thereby causing contact with the incident light. It is desirable that the arc-shaped members constituting the optical member 11 movable in the radial direction have a thickness in the optical axis direction, similar to the optical member 11 movable in the optical axis direction. The thickness at this time is desirably 0.1 mm to 4.0 mm, similar to the first embodiment described above. Even if the optical member 11 does not have a thickness in the optical axis direction, it is possible for it to come into contact with the 70% image height ray to the 100% image height ray, which is the incident light. However, if there is no thickness in the optical axis direction, there is a risk that it will become too small. As a result, the scattering area and illuminance of flare and ghosts appearing in the captured image may become smaller, which may reduce the desired effect on image creation.

[0038] In the embodiments of the present application, the 100% and 70% image height rays of the incident light have been used for explanation. However, it goes without saying that the present invention is not limited to the 100% and 70% image height rays. In optical design, there is no problem if flare or ghost appears in the captured image by generating scattered light using other image height rays.

[0039] Furthermore, it goes without saying that the captured images of the present invention include not only still images but also moving images. [Explanation of symbols]

[0040] 1 Lens barrel 10 Aperture 11 Optical components 111 Light-shielding material 112 Glossy materials 20 Optical elements 21 Presser I Image sensor

Claims

1. Multiple lenses and An aperture that adjusts the amount of incoming light; In a lens barrel having an optical member movable within the lens barrel independently of focusing and magnification operations; an operating member for moving the optical member; A lens barrel comprising:

2. a moving direction of the optical member by operating the operation member is a direction along the optical axis, 2. The lens barrel according to claim 1, wherein the optical member is movable, thereby making it possible to switch between generation and non-generation of stray light.

3. a direction in which the optical member is moved by operating the operation member is a direction perpendicular to the optical axis, 2. The lens barrel according to claim 1, wherein the optical member is movable, so that occurrence of stray light can be switched on and off.

4. the optical member includes a light-shielding member and a glossy member, the aperture, the light blocking member, and the gloss member in this order from the object side; 2. The lens barrel according to claim 1, wherein the light blocking member is moved along an optical axis by operating the operating portion, thereby making it possible to switch between generation and non-generation of stray light.

5. 4. The lens barrel according to claim 2, wherein the optical member is located on the image plane side of the aperture stop.

6. 5. The lens barrel according to claim 2, wherein the movable range of the optical member is from a state where the optical member is not in contact with the incident light to a state where the optical member is in contact with an upper ray that is incident at 70% of the image height of the incident light.

7. 4. The lens barrel according to claim 2, wherein the width d of the optical member in the optical axis direction satisfies the following conditional expression: (Conditional expression) 0.1≦d≦4.0 (mm)

8. 5. The lens barrel according to claim 2, wherein the optical member has a reflectance of 2% or more.

9. 5. The lens barrel according to claim 2, wherein some of the lenses are disposed between the diaphragm and the optical member.

Images