Patent Application
20240048831
The utility model relates to the technical field of lens, in particular, to a tele-converter structure with an adjustable back focal length.
Tele-converter is an additional lens on the camera, which, when used in conjunction with the main lens of the camera, magnifies the original object to transmit the full frame. When the tele-converter is applied to different cameras and main lenses, due to the gap among the tele-converter, the camera and the main lens, it will cause the problem of inaccurate back focal length of the main lens. Therefore, adjustments for the back focal length of the main lens are required to achieve the desired sharpness.
The applicant found in practice that most of the tele-converter in the prior art are designed in fixed structures. When the tele-converter is used with a camera and the main lens, additional tools are required to adjust the back focal length of the main lens each time by unscrewing the screws on the lens mount first, then removing the mount to replace the gasket and then putting the mount on to re-screw the screws.
Obviously, for the operation mode in the prior art, it is cumbersome, the screw is easily damaged to cause damage to the lens, and there is no guarantee that a replacement can achieve the desired effect with certain experience and judgment; the detachment is required for many times, and the steps are repeated and troublesome, which brings great trouble to the user.
The utility model aims at providing a tele-converter structure with an adjustable back focal length for the shortcomings of the prior art, wherein a convenient back focal length adjustment structure is set in the tele-converter, so as to meet the requirements in back focal adjustment of different main lenses by adjusting the back focal length of the tele-converter.
To achieve the above objective, the utility model adopts the following technical solutions:
A tele-converter structure with an adjustable back focal length includes:
In the above technical solutions, the camera body adapter and the lens adapter belong to the existing mount structure in the prior art, and may be a PL mount/an EF mount/an E mount/an L mount/a RF mount/an X mount respectively, so as to be suitable for cameras and main lenses with corresponding mount structures with the advantage of convenient disassembly and assembly. In actual use, first the tele-converter structure with an adjustable back focal length in the above technical solutions is assembled to the lens of the camera itself through the camera body adapter, and then the selected main lens is assembled through the lens adapter, so that the tele-converter may be quickly applied to the camera and the main lens without additional tools.
In the above technical solutions, since the inner rotating ring is driven to move axially by way of spirally transmitting when the focusing ring is rotated, the lens cylinder is also moved axially in synchronization with the focusing ring through the guide columns. Therefore, in actual use, the lens cylinder may be easily fine-tuned axially through the focusing ring, so that the back focal length of the main lens may be quickly calibrated, and there is no need to repeatedly disassemble and assemble for debugging.
Compared with the prior art, the utility model has the following beneficial effects: no additional auxiliary tools are required for installation, and the back focal length may be adjusted directly without disassembly after installation, which improves the efficiency and significantly enhances the convenience of operation.
Hereinafter, the utility model will be further described with reference to the accompanying drawings and specific embodiments.
As shown in
In the above embodiment, since the inner rotating ring 4 is driven to move axially by way of spirally transmitting when the focusing ring 7 is rotated, the lens cylinder 1 is also moved axially in synchronization with the focusing ring 7 through the guide columns 2. Therefore, in actual use, the lens cylinder 1 may be easily fine-tuned axially through the focusing ring 7, so that the back focal length of the main lens may be quickly calibrated, and there is no need to repeatedly disassemble and assemble for debugging.
In a preferred embodiment, the tele-converter structure is provided with at least three guide columns 2 symmetrically distributed at equal angular distances around a central axis of the lens cylinder 1, so that the lens cylinder 1 has better axial stability during axial movement.
In a preferred embodiment, the guiding column 2 includes a screw barrel 21, an outer sheath 22 coaxially sleeved outside the screw barrel 21, and a socket set screw 23 coaxially inserted into the screw barrel 21; an upper end of the outer sheath 22 forms a counterbore 221 fitted with the socket set screw 23, and the socket set screw 23 penetrates down through the screw barrel 21 via the counterbore 221 to be screwed to the lens cylinder 1. With this arrangement, the guiding column 2 may be installed from the outside to the inside through the positioning hole 43 and the guiding hole 33 in sequence, which reduces the difficulty of assembly.
In a preferred embodiment, an outer wall of the lens cylinder 1 is provided with a supporting ring 13 that is coaxially arranged, and the guiding column 2 is connected to an outer annular surface of the supporting ring 13, so that the supporting ring 13 bears the shear force transmitted by the guide column 2, which facilitates the protection of the structure of the lens cylinder 1.
In a preferred embodiment, a first washer 701 to reduce sliding friction is provided between a front end surface of the focusing ring 7 and the lens adapter 6, and a second washer 702 to reduce sliding friction is provided between a rear end surface of the focusing ring 7 and the camera body adapter 5 and the length adapter 6.
In a preferred embodiment, an annular elastic sheet 40 coaxial with the drum body 31 is provided between a front end surface of the annular body 41 and a rear end surface of the convex ring 32, and an elastic tight fit is maintained between the front end surface of the annular body 41 and the rear end surface of the convex ring 32 through the annular elastic sheet 40, so that the axial matching gap between the inner rotating ring 4 and the lens adapter 6 is eliminated by an elastic force of the annular elastic sheet 40 to ensure that the inner rotating ring 4 is driven to move axially by way of spirally transmitting when the focusing ring 7 is rotated and to avoid the inner rotating ring 4 from idling synchronously with the focusing ring 7.
In a preferred embodiment, the outer annular surface of the focusing ring 7 is provided with a first gear ring 72 that is coaxially arranged, and an outer round surface of the first gear ring 72 is provided with a concave/convex texture for increasing friction to prevent slippage when the user rotates the focusing ring 7.
In a preferred embodiment, the outer annular surface of the focus lock ring 8 is provided with a plurality of bosses 82 symmetrically distributed at equal angular distances around the central axis, and a top portion of the boss 82 is provided with a buckle position 84 formed due to the depression, so that the user operates the focus lock ring 8 by snapping into the buckle position 84 with a finger, thereby adjusting the focus lock ring 8 more conveniently and reliably.
For those skilled in the art, the protection scope of the invention is not limited to the details of the above-mentioned exemplary embodiments. Without departing from the spirit or essential characteristics of the invention, all modified embodiments within the equivalent meaning and protection scope made by those skilled in the art based on the requirements of the invention shall be included in the invention.
