Large-format camera

Abstract

The invention discloses a large-format camera which comprises a base, a front lens assembly arranged at the front part of the base, a connecting bridge which is connected to the rear part of the base and of which the bridge body is suspended above the base, and a back view finding assembly which is detachably connected to the connecting bridge through a threaded fastener, a bridge body of the connecting bridge is provided with a supporting face used for supporting the back framing assembly and a vertically-through lower threaded hole, and an upper threaded hole is formed in the bottom of the back framing assembly. The threaded fastener is in threaded engagement with the upper threaded hole and the lower threaded hole, a nut is arranged at the bottom end of the threaded fastener, and the nut is screwed to enable the threaded fastener to descend to be separated from the upper threaded hole; the suspension height of the connecting bridge is suitable for enabling a part of the threaded fastener to be located in the lower threaded hole when the nut is supported on the base; a vertically-through guide hole is formed in the position, corresponding to the threaded fastener, of the base so that a rotating rod used for screwing a nut can slide upwards to penetrate through the guide hole. The beneficial effect of the invention is that the back framing assembly can be quickly disassembled and replaced.

Description

Technical Field

[0001] The present invention relates to a large-format camera, belonging to the field of professional photographic imaging equipment. Background Art

[0002] Due to its high image quality and modular design, large-format cameras are widely used in the field of professional photography. Especially in scenes such as landscapes and architecture that require precise composition and flexible adjustment, it is often necessary to replace the rear viewfinder components with different functions (such as digital backs, film backs, etc.) to meet the shooting needs. However, the longer the replacement time of the rear viewfinder component, the greater the risk of missing the best shooting opportunity, such as in scenes with rapidly changing light (such as dusk, fleeting weather). Summary of the Invention

[0003] The object of the present invention is to provide a large-format camera that can quickly disassemble and replace the rear viewfinder component.

[0004] The present invention is achieved by the following technical solutions.

[0005] A large-format camera includes a base, a front lens assembly disposed at the front of the base and capable of adjusting its position back and forth, a connecting bridge connected to the rear of the base and having a bridge body suspended above the base, a rear viewfinder component detachably connected to the connecting bridge through a threaded fastener, and a bellows detachably connecting the front lens assembly and the rear viewfinder component; The bridge body of the connecting bridge has a support surface for supporting the rear viewfinder component and a lower threaded hole vertically penetrating. The bottom of the rear viewfinder component has an upper threaded hole corresponding to the lower threaded hole and being a blind hole; the threaded fastener is threadedly engaged with the upper threaded hole and the lower threaded hole, and the bottom end of the threaded fastener has a nut. By screwing the nut, the threaded fastener can be lowered to disengage from the upper threaded hole; the suspended height of the connecting bridge is such that when the nut supports on the base, a part of the threaded fastener is located in the lower threaded hole; the base has a vertically penetrating guide hole at a position corresponding to the threaded fastener to allow a rod for screwing the nut to slide upward through.

[0006] As a further improvement of the present invention, at least one vertically protruding locking post is respectively disposed on both sides of the support surface of the connecting bridge at positions corresponding to the lower threaded hole. The bottom of the rear viewfinder component has a locking hole at a position corresponding to the locking post, and the locking post and the locking hole are inserted and matched.

[0007] As a further improvement of the present invention, a positioning wall formed by a protrusion and extending in the left-right direction is provided at the front of the support surface of the connecting bridge. The positioning wall has an abutting wall surface that abuts against the front surface of the rear viewfinder component for positioning the front-rear position of the rear viewfinder component on the support surface.

[0008] As a further improvement of the present invention, the positioning wall has at least one interruption part and forms a positioning slot; a convex structure protruding forward is provided at a position corresponding to the positioning slot on the front surface of the rear view-finding assembly, and the positioning slot and the convex structure are inserted and matched to position the left and right positions of the rear view-finding assembly on the support surface.

[0009] As a further improvement of the present invention, the support surface has a concave hole for setting the locking post, and an elastic member for supporting the bottom of the locking post and the bottom of the concave hole is provided in the concave hole; the locking post can be retracted into the concave hole and hidden under the support surface in a compressed state, and the elastic member is used to provide an elastic force so that the locking post pops out and protrudes from the support surface in a non-compressed state.

[0010] As a further improvement of the present invention, magnetic components that magnetically attract each other are respectively provided in the positioning wall and in the rear view-finding assembly.

[0011] As a further improvement of the present invention, the screwdriver rod is provided by a screwdriver that matches the nut.

[0012] As a further improvement of the present invention, a positioning cylinder surrounding the lower threaded hole is provided at the bottom of the base, a rotary cover is slidably sleeved outside the positioning cylinder, the screwdriver rod passing through the guiding hole is provided at the bottom of the rotary cover, and the rotary cover and the screwdriver rod define a lowest horizontal position; when the screwdriver rod screws the nut to make the threaded fastener descend and disengage from the upper threaded hole, the rotary cover and the screwdriver rod reach their lowest horizontal position.

[0013] As a further improvement of the present invention, the positioning cylinder has a limiting plate allowing the screwdriver rod to pass through, a limiting member that can abut against the limiting plate is provided on a part of the screwdriver rod located between the base and the limiting plate, and when the limiting member abuts against the limiting plate, the rotary cover and the screwdriver rod are in the lowest horizontal position.

[0014] As a further improvement of the present invention, a sliding rail extending forward and backward is provided on the base, a sliding frame with adjustable front and rear positions is provided on the sliding rail, and the front lens assembly is mounted on the sliding frame.

[0015] Advantages of the present invention: By setting a detachable connection structure between the connecting bridge and the rear viewfinder component, this large-format camera can flexibly adapt to rear viewfinder components with various functions or specifications. This solution simplifies the structural complexity through the connection method of a single threaded fastener, enabling users to quickly switch different rear components according to the shooting scene requirements. For example, in a sunset scene with rapidly changing light, users do not need to spend a lot of time adjusting or refixing due to replacing the rear component. They only need to operate a single connection point to complete the replacement, significantly shortening the gap between switching different viewfinder modules and avoiding missing the best shooting opportunity due to time delay.

[0016] The guiding hole design on the base enables the rotating rod to quickly penetrate the base along a fixed path and align with the nut of the threaded fastener, achieving precise guidance for the disassembly action. During the traditional disassembly process, users need to repeatedly adjust the alignment between the rotating rod and the nut. However, in this solution, the axial limit of the rotating rod by the guiding hole directly guides the rotating rod to contact the nut, eliminating the possibility of alignment deviation. At the same time, the threaded fastener always partially remains in the lower threaded hole of the connecting bridge during disassembly, avoiding the cumbersome steps of reinstalling or calibrating after the thread detachment. This design not only ensures the instantaneous response during the disassembly process but also retains the preset thread meshing starting point for subsequent installation, further reducing the overall replacement time.

[0017] The double-thread cooperation of a single threaded fastener with the upper and lower threaded holes simplifies the connection structure while enhancing the connection strength through the dual friction effect of the upper and lower thread meshing surfaces, compensating for the potential lack of stability in single-point fixation. Although the double-thread meshing increases the rotational resistance of the threaded fastener, the rigid constraint of the guiding hole on the rotating rod ensures that the rotating rod always applies force in the vertical direction during operation, avoiding thread misalignment or jamming caused by the axial deviation of the rotating rod. This precise guiding mechanism effectively offsets the impact of the double-thread friction on the operation efficiency, enabling users to maintain a stable force application direction during quick disassembly and assembly, avoiding additional time loss caused by sudden resistance changes or operation errors, and ultimately achieving a balanced optimization of connection strength and operation efficiency. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] The preferred embodiments of the present invention will be described in detail below with reference to the drawings to help understand the purpose and advantages of the present invention, where: Figure 1 is a schematic structural diagram of a large-format camera; Figure 2 is a schematic diagram of the connecting bridge and the rear viewfinder component from one perspective; Figure 3 is a schematic diagram of the connecting bridge and the rear viewfinder component from another perspective; Figure 4 is a schematic structural diagram of the connecting bridge; Figure 5It is a structural schematic diagram of the rear viewfinder assembly; Figure 6 It is a sectional schematic diagram of the locking post; Figure 7 It is a sectional schematic diagram of the base of the rotating rod in the second embodiment. Specific embodiments

[0019] The present invention will be further described in detail below with reference to the drawings and embodiments.

[0020] The orientation terms such as up, down, left, right, front, back, front side, back side, top, bottom, etc. mentioned or possibly mentioned in this specification are defined with respect to the structures shown in the respective drawings. The terms "inner" and "outer" respectively refer to the directions towards or away from the geometric center of a specific component. They are relative concepts and may accordingly change depending on their different positions and usage states. Therefore, these or other orientation terms should not be construed as restrictive terms.

[0021] A large-format camera, referring to Figures 1-7 , includes a base 1, a front lens assembly 2 disposed at the front of the base 1 and capable of adjusting its position back and forth, a connecting bridge 3 connected to the rear of the base 1 and having a bridge body suspended above the base 1, a rear viewfinder assembly 4 detachably connected to the connecting bridge 3 by a threaded fastener 5, and a bellows (not shown in the figure) detachably connecting the front lens assembly 2 and the rear viewfinder assembly 4.

[0022] For the connecting bridge 3, its left and right ends are respectively connected to the left and right sides of the rear part of the base 1, and its bridge body is suspended above the base 1 in a posture spanning the base 1. The bridge body of the connecting bridge 3 has a support surface 31 for supporting the rear viewfinder assembly 4 and a vertically penetrating lower threaded hole h2, and the lower threaded hole h2 is located at the middle position of the connecting bridge 3. The bottom of the rear viewfinder assembly 4 has an upper threaded hole h1 corresponding to the lower threaded hole h2 and being a blind hole. The threaded fastener 5 is threadedly engaged with both the upper threaded hole h1 and the lower threaded hole h2 at the same time to realize the connection relationship between the rear viewfinder assembly 4 and the connecting bridge 3. The bottom end of the threaded fastener 5 has a nut 51. When the threaded fastener 5 is fully threadedly engaged with the upper threaded hole h1, the nut 51 abuts against the bottom surface of the connecting bridge 3. The nut 51 is turned to make the threaded fastener 5 descend and disengage from the upper threaded hole h1, that is, the rear viewfinder assembly 4 is disassembled from the connecting bridge 3. The suspended height of the connecting bridge 3 is adapted such that when the nut 51 is supported on the base 1, a part of the threaded fastener 5 is located in the lower threaded hole h2, that is, when the rear viewfinder assembly 4 is disassembled, the threaded fastener 5 will never disengage from the lower threaded hole h2. The part of the base 1 corresponding to the threaded fastener 5 has a vertically penetrating guide hole h3 to allow the lever 63 for turning the nut 51 to slide upward through, and due to the relationship of sliding through, when the lever 63 turns the nut 51, its axis will never deflect.

[0023] By providing a detachable connection structure between the connecting bridge 3 and the rear viewfinder assembly 4, this large-format camera can flexibly adapt to rear viewfinder assemblies 4 with various functions or specifications. In traditional designs, the rear viewfinder assembly 4 usually requires complex fixing structures or tool-assisted disassembly and assembly. However, in this solution, the connection method of a single threaded fastener 5 simplifies the structural complexity, enabling users to quickly switch different rear components according to the shooting scene requirements. For example, in a sunset scene with rapidly changing light, users do not need to spend a lot of time adjusting or refixing due to replacing the rear component. They only need to operate a single connection point to complete the replacement, significantly shortening the gap between switching different viewfinder modules and avoiding missing the best shooting opportunity due to time delay.

[0024] The design of the guide hole h3 on the base 1 enables the lever 63 to quickly penetrate the base 1 along a fixed path and align with the nut 51 of the threaded fastener 5, realizing precise guidance for the disassembly action. During the traditional disassembly process, users need to repeatedly adjust the alignment between the lever 63 and the nut 51. However, in this solution, the axial limit of the lever 63 by the guide hole h3 directly guides the lever 63 to contact the nut 51, eliminating the possibility of alignment deviation. At the same time, the threaded fastener 5 always partially remains in the lower threaded hole h2 of the connecting bridge 3 during disassembly, avoiding the cumbersome steps of reinstalling or calibrating after the threads are disengaged. This design not only ensures the instantaneous response of the disassembly process but also preserves a preset thread engagement starting point for subsequent installation, further shortening the overall replacement time.

[0025] The double-threaded fit of the single threaded fastener 5 with the upper threaded hole h1 and the lower threaded hole h2 not only simplifies the connection structure, but also improves the connection strength through the double friction of the upper and lower thread meshing surfaces, compensating for the potential lack of stability of single-point fixation. Although the double-threaded meshing increases the rotational resistance of the threaded fastener 5, the rigid constraint of the guide hole h3 on the rotating rod 63 ensures that the rotating rod 63 always applies force in the vertical direction during operation, avoiding thread misalignment or jamming caused by the axial deflection of the rotating rod 63. This precise guiding mechanism effectively offsets the influence of the double-thread friction on the operation efficiency, enabling the user to maintain a stable force application direction during rapid disassembly and assembly, avoiding additional time loss caused by sudden changes in resistance or operation errors, and ultimately achieving a balanced optimization of connection strength and operation efficiency.

[0026] In this embodiment, at least one locking post 32 is provided on each side of the support surface 31 of the connection bridge 3 located on both sides of the lower threaded hole h2, and the locking post 32 protrudes vertically from the support surface 31. The bottom of the rear viewfinder assembly 4 has a locking hole h4 at the position of the locking post 32, and the locking post 32 and the locking hole h4 are inserted and matched. The insertion and matching of the locking post 32 and the locking hole h4, through physical locking, forcibly restricts the relative position of the rear viewfinder assembly 4 and the connection bridge 3, ensuring the precise alignment of the upper threaded hole h1 and the lower threaded hole h2 during installation. The setting of the locking post 32 and the locking hole h4 not only simplifies the installation steps, but also enables the upper threaded hole h1 and the lower threaded hole h2 to be precisely aligned, avoiding the risk of repeated trial tightening or thread damage caused by thread misalignment, enabling the threaded fastener 5 to be quickly and smoothly screwed into the upper threaded hole h1, and further reducing the replacement time of the rear viewfinder assembly 4. In addition, the insertion and matching of the locking post 32 and the locking hole h4 forms an additional mechanical support structure on the basis of the connection of the single threaded fastener 5, effectively dispersing the lateral or rotational forces during the use of the rear viewfinder assembly 4. Since the connection bridge 3 and the rear viewfinder assembly 4 are fixed only by a single threaded fastener 5, its anti-torsion ability may be limited by the friction of the thread meshing surface. After the locking post 32 is inserted into the locking hole h4, through the contact between the side wall of the column and the hole wall, it can directly bear the lateral load caused by external forces, reducing the risk of loosening of the threaded fastener 5 due to uneven force during dynamic use. This double connection mechanism not only maintains the convenience of rapid disassembly and assembly, but also shares the load of the threaded connection through the insertion structure, making the overall connection more stable, avoiding the need for repeated adjustment due to component shaking caused by insufficient connection strength, and thus indirectly shortening the additional operation time caused by stability problems.

[0027] In this embodiment, the connecting bridge 3 has a positioning wall 33 formed by a protrusion at the front of its supporting surface 31 and extending in the left-right direction. The positioning wall 33 has an abutting wall surface 331 that abuts against the front surface of the rear viewfinder assembly 4, and is used to position the front-rear position of the rear viewfinder assembly 4 on the supporting surface 31. The positioning wall 33 has at least one interrupted portion and forms a positioning slot 34. A protruding structure 41 that protrudes forward is provided at a portion of the front surface of the rear viewfinder assembly 4 corresponding to the positioning slot 34. The positioning slot 34 and the protruding structure 41 are inserted and matched with each other to position the left-right position of the rear viewfinder assembly 4 on the supporting surface 31.

[0028] The abutting wall surface 331 of the positioning wall 33 physically blocks the front surface of the rear viewfinder assembly 4 to forcibly restrict its front-rear position on the supporting surface 31. During the traditional installation process, the user needs to manually adjust the front-rear alignment of the rear viewfinder assembly 4 to ensure that the threaded holes are aligned. However, the abutting function of the positioning wall 33 enables the rear assembly to automatically fit to the preset front-rear reference position when placed. This setting eliminates the manual fine-tuning step in the front-rear direction during installation and avoids the situation where the threaded holes are misaligned and cannot be engaged due to front-rear deviation. The insertion and matching of the positioning slot 34 and the protruding structure 41 precisely restricts the left-right position of the rear viewfinder assembly 4 through a lateral limiting effect. The slot formed by the interrupted portion of the positioning wall 33 and the protrusion on the assembly form a "mortise and tenon" fit, which forces the rear viewfinder assembly 4 to be guided to the preset lateral reference point when moving left and right. This setting ensures that the alignment tolerance of the threaded holes in the left-right direction approaches zero through mechanical insertion.

[0029] The synergistic effect of the positioning wall 33 and the slot forms a dual physical limit in the front-rear and left-right dimensions, and together with the vertical insertion and matching of the original locking post 32, a three-dimensional positioning system is constructed. This system enables the rear assembly to quickly and accurately reach the preset three-dimensional space coordinates during installation, ensuring that the upper and lower threaded holes h2 are completely aligned. At the same time, the multi-dimensional mechanical limits disperse the force application directions when the rear assembly is in use. For example, the abutting wall surface 331 can resist the front-rear thrust during the shooting operation, and the slot and the protrusion can inhibit the left-right torsion, thereby reducing the risk of connection loosening caused by external forces. This setting not only shortens the installation time through precise positioning but also reduces the need for secondary adjustment due to insufficient stability during use through multi-dimensional reinforcement, ultimately achieving the synchronous optimization of the replacement efficiency and connection reliability.

[0030] In this embodiment, the support surface 31 has a concave hole h5 for setting the locking column 32, and an elastic member 321 is provided in the concave hole h5 to support the bottom of the locking column 32 and the bottom of the concave hole h5. The locking column 32 can be retracted into the concave hole h5 and hidden under the support surface 31 under pressure. The elastic member 321 is used to provide elastic force so that the locking column 32 is raised from the support surface 31 under non-pressure. More specifically, a vertical guide column 322 is provided in the concave hole h5, and the locking column 32 is inserted on the guide column 322 and can slide up and down. The elastic member 321 is configured as a spring and is arranged around the guide column 322.

[0031] The retractable and pop-up setting of the locking post 32 allows the locking post 32 to be temporarily pressed into the recessed hole h5 by pressure when the back viewfinder component 4 is initially placed, thereby eliminating the physical obstruction of its protrusion to the movement of the component. Otherwise, the movement of the component will be blocked by the locking post 32 and the position cannot be adjusted. The retractable and pop-up setting of the locking post 32 allows the user to press the component directly to the support surface 31 without precise pre-positioning, and then freely adjust it to the preset position of the abutting wall 331 and the positioning slot 34. This process greatly reduces the accuracy requirements for initial placement and simplifies the operating steps. The automatic reset feature of the elastic member 321 ensures that after the back viewfinder assembly 4 is adjusted into place, the locking column 32 immediately pops out and precisely plugs into the locking hole h4. When the back viewfinder assembly 4 completes the alignment in the front-to-back and left-to-right directions through the positioning wall 33 and the slot, the position of the locking hole h4 is naturally aligned with the locking column 32. At this time, the elastic force of the elastic member 321 pushes the locking column 32 up to a non-pressurized state to achieve "passive locking". This mechanism does not require additional operation, which not only avoids interrupting the installation process due to distracted operation of the locking column 32, but also ensures the stability of the connection through the physical self-locking feature. In addition, the "avoid first, lock later" feature of the elastic locking column 32, the division of labor and cooperation between the positioning wall 33 and the slot, decompose the installation process into three efficient steps of "rough placement → fine positioning → automatic locking". This staged operation mode greatly simplifies the user's operation complexity through physical guidance.

[0032] In this embodiment, magnetic components (not shown in the figure) that are magnetically attracted to each other are respectively provided in the positioning wall 33 and the back viewfinder component 4; more specifically, magnetic components that are magnetically attracted to each other are provided in the positioning wall 33 located on both sides of the positioning slot 34 and the left and right parts of the back viewfinder component 4.

[0033] When the back viewfinder assembly is initially placed on the support surface 31, the magnetic attraction effect of the magnetic component automatically pulls it toward the abutting wall 331 of the positioning wall 33 through magnetic traction, eliminating the manual coarse adjustment step in the front and back directions. The magnetic attraction effect allows the assembly to be adsorbed to a position close to the target position the moment it contacts the support surface 31, and the front and back fitting can be completed with only slight pressure or release.

[0034] The symmetric distribution of the magnetic components on the left and right sides forms a horizontal magnetic balance, guiding the rear view component to automatically converge towards the center position of the positioning slot 34 when moving left and right. After the component abuts against the wall surface 331 under the action of magnetic attraction, the left and right magnetic attractions form a "centripetal force", enabling the user to feel the magnetic guidance when slightly adjusting the rear view component 4 left and right. The user only needs to gently push the component to perceive the alignment trend between the protruding structure 41 and the slot. When the user slides the component left and right, the magnetic attraction will naturally weaken the resistance when deviating from the center and enhance the adsorption feeling when approaching the slot, just like physical tactile feedback, helping for quick positioning and reducing the trial-and-error cost of left and right calibration.

[0035] The synergistic effect of magnetic attraction and mechanical positioning structure forms a two-stage efficient mode of "magnetic pre-positioning + mechanical fine positioning". After the magnetic attraction completes the large-range spatial guidance of the component, the rigid structure of the positioning wall 33 and the slot is responsible for the final precise limit, and their division of labor is clear. For example, when the component is magnetically attracted to be near the wall surface 331, there may still be a deviation of millimeters. At this time, the user only needs to slightly slide left and right along the magnetic guidance, and the protruding structure 41 will be guided to the fully inserted state by the dual guidance of magnetic force and physical limit of the slot. This mechanism not only utilizes the fast response characteristic of magnetic attraction to cover the rough adjustment stage but also retains the control ability of the mechanical structure for micron-level precision, overall shortening the full process time from placement to locking.

[0036] In the first implementation mode, the rotating rod 63 is provided by a screwdriver matching the thread of the nut 51. The screwdriver is an external tool, which can specifically be a screwdriver, a hexagon wrench, etc. Since the screwdriver is an external tool, the user can select a suitable model according to the existing equipment, reducing the design complexity and manufacturing cost. However, in an actual quick disassembly scenario, the operator needs to carry an additional tool and complete a multi-step process of "retrieving the tool → aligning with the guide hole h3 → inserting the rotating rod 63 → turning the nut 51".

[0037] In the second implementation mode, a positioning cylinder 61 surrounding the lower threaded hole h2 is provided at the bottom of the base 1. A rotating cover 62 is slidably sleeved outside the positioning cylinder 61. The bottom of the rotating cover 62 is provided with a rotating rod 63 passing through the guide hole h3. The rotating cover 62 and the rotating rod 63 are limited to the lowest horizontal position; when the rotating rod 63 turns the nut 51 and the threaded fastener 5 descends and disengages from the upper threaded hole h1, the rotating cover 62 and the rotating rod 63 reach their lowest horizontal position.

[0038] By integrating the linkage structure of the screw cap 62, the screw rod 63 and the base 1, a tool-free one-piece rapid operation is achieved. The screw cap 62 and the screw rod 63, as inherent components of the base 1, always maintain a spatial relationship with the nut 51. During disassembly, the user only needs to push the screw cap 62 upward with one hand, and the screw rod 63 will automatically align with the nut 51 through the axial constraint of the guide hole h3, saving the time for alignment and insertion of external tools. The sliding fit between the screw cap 62 and the positioning cylinder 61 defines the lowest horizontal position of the screw rod 63. When the screw cap 62 rotates to the lowest horizontal position, the threaded fastener 5 has completely disengaged from the upper threaded hole h1, and the rear viewfinder assembly 4 is immediately unlocked. This setting replaces the traditional manual operation of judging the tightness degree through physical limitation, avoiding problems such as thread wear or incomplete disassembly caused by excessive screwing. The user only needs to rotate the screw cap 62 to the position where it cannot be pressed down further to ensure that the threaded fastener 5 is in a completely disengaged state, eliminating the redundant steps of repeatedly verifying the disassembly state. In addition, the pushing and rotating actions of the screw cap 62 are continuous one-way operations. When the user pushes the screw cap 62 upward, the top of the screw rod 63 automatically presses against the nut 51; then, rotating the screw cap 62 clockwise can synchronously complete the screwing of the nut 51 and the lowering of the threaded fastener 5. The whole process does not require switching gestures or adjusting the force application direction, and the operation fluency is significantly better than the step-by-step operation of external tools.

[0039] In this embodiment, the positioning cylinder 61 has a limiting plate 611 that allows the screw rod 63 to pass through. A limiting member 631 that can abut against the limiting plate 611 is provided on the part of the screw rod located between the base 1 and the limiting plate 611, and when the limiting member 631 abuts against the limiting plate 611, the screw cap 62 and the screw rod 63 are in the lowest horizontal position.

[0040] In this embodiment, a sliding rail 11 extending forward and backward is provided on the base 1. A sliding frame 12 with an adjustable front and rear position is arranged on the sliding rail 11, and the front lens assembly 2 is installed on the sliding frame 12. A knob for controlling the front and rear position of the sliding frame 12 is provided on the side of the base 1, and the user can adjust the front and rear position of the front lens assembly 2 by rotating the knob.

[0041] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those of ordinary skill in the art should understand that they can still modify the technical solutions recorded in the foregoing embodiments, or perform equivalent replacements on some of the technical features; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A large-format camera, characterized in that, It includes a base (1), a front lens assembly (2) disposed at the front of the base (1) and capable of adjusting its position back and forth, a connecting bridge (3) connected to the rear of the base (1) with its bridge body suspended above the base (1), a rear viewfinder assembly (4) detachably connected to the back of the connecting bridge (3) by a threaded fastener (5), and a bellows detachably connecting the front lens assembly (2) and the rear viewfinder assembly (4). The bridge body of the connecting bridge (3) has a support surface (31) for supporting the rear viewfinder assembly (4) and a vertically penetrating lower threaded hole (h2). The bottom of the rear viewfinder assembly (4) has an upper threaded hole (h1) corresponding to the lower threaded hole (h2) and being a blind hole. The threaded fastener (5) is threadedly engaged with the upper threaded hole (h1) and the lower threaded hole (h2). The bottom end of the threaded fastener (5) has a nut (51). By screwing the nut (51), the threaded fastener (5) can be lowered to disengage from the upper threaded hole (h1). The suspended height of the connecting bridge (3) is such that when the nut (51) supports on the base (1), a part of the threaded fastener (5) is located within the lower threaded hole (h2). The base (1) has a vertically penetrating guide hole (h3) at a position corresponding to the threaded fastener (5) to allow a lever (63) for screwing the nut (51) to slide upward through it.

2. The large-format camera according to claim 1, characterized in that, On both sides of the lower threaded hole (h2) of the support surface (31) of the connecting bridge (3), there are at least one vertically protruding locking post (32) respectively. The bottom of the rear viewfinder assembly (4) has a locking hole (h4) corresponding to the locking post (32), and the locking post (32) and the locking hole (h4) are in plug-in fit.

3. The large-format camera according to claim 2, wherein At the front of the support surface (31) of the connecting bridge (3), there is a positioning wall (33) formed by a protrusion and extending in the left-right direction. The positioning wall (33) has an abutting wall surface (331) that abuts against the front of the rear viewfinder assembly (4) for positioning the front-rear position of the rear viewfinder assembly (4) on the support surface (31).

4. The large-format camera according to claim 3, characterized in that, The positioning wall (33) has at least one interrupted part and forms a positioning slot (34). At a position corresponding to the positioning slot (34) on the front of the rear viewfinder assembly (4), there is a protruding structure (41) protruding forward. The positioning slot (34) and the protruding structure (41) are in plug-in fit for positioning the left-right position of the rear viewfinder assembly (4) on the support surface (31).

5. The large-format camera according to claim 4, wherein The support surface (31) has a concave hole (h5) for setting the locking post (32). An elastic member (321) for supporting the bottom of the locking post (32) and the bottom of the concave hole (h5) is provided in the concave hole (h5). The locking post (32) can be retracted into the concave hole (h5) and hidden under the support surface (31) in a compressed state, and the elastic member (321) is used to provide elastic force to make the locking post (32) pop out and protrude from the support surface (31) in a non-compressed state.

6. The large-format camera according to claim 5, characterized in that, A magnetic component that magnetically attracts each other is provided inside the positioning wall (33) and inside the rear viewfinder assembly (4).

7. The large-format camera according to claim 1, characterized in that, The rotating rod (63) is provided by a screwdriver that matches the thread of the nut (51).

8. The large-format camera according to claim 1, wherein A positioning cylinder (61) surrounding the lower threaded hole (h2) is provided at the bottom of the base (1). A rotating cover (62) is slidably sleeved outside the positioning cylinder (61). The bottom of the rotating cover (62) is provided with the rotating rod (63) passing through the guiding hole (h3). The rotating cover (62) and the rotating rod (63) define a lowest horizontal position. When the rotating rod (63) screws the nut (51) to make the threaded fastener (5) descend and disengage from the upper threaded hole (h1), the rotating cover (62) and the rotating rod (63) reach their lowest horizontal position.

9. The large-format camera according to claim 8, wherein, The positioning cylinder (61) has a limiting plate (611) that allows the rotating rod (63) to pass through. A limiting member (631) that can abut against the limiting plate (611) is provided on the part of the rotating rod (63) between the base (1) and the limiting plate (611). When the limiting member (631) abuts against the limiting plate (611), the rotating cover (62) and the rotating rod (63) are in the lowest horizontal position.

10. The large-format camera according to any one of claims 1-9, characterized in that, A sliding rail (11) extending forward and backward is provided on the base (1). A sliding bracket (12) whose position can be adjusted forward and backward is arranged on the sliding rail (11). The front lens assembly (2) is installed on the sliding bracket (12).

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