A large format camera

Abstract

The application discloses a large-format camera, which comprises a base, a front lens assembly arranged at the front of the base, a connecting bridge connected at the back of the base and suspended above the base, and a back viewfinder assembly detachably connected to the connecting bridge through a threaded fastener; the connecting bridge has a support surface for supporting the back viewfinder assembly and a vertically-through lower threaded hole, and the bottom of the back viewfinder assembly has an upper threaded hole; the threaded fastener is in threaded engagement with the upper threaded hole and the lower threaded hole, the bottom end of the threaded fastener is provided with a nut, and the nut is loosened to make the threaded fastener descend and be separated from the upper threaded hole; the suspended height of the connecting bridge is suitable for enabling the threaded fastener to be partially located in the lower threaded hole when the nut is supported on the base; and the base is provided with a vertically-through guide hole corresponding to the position of the threaded fastener to allow a rotating rod for loosening the nut to slide upwardly through. The application has the beneficial effect that the back viewfinder assembly can be quickly disassembled and replaced.

Description

Technical Field

[0001] This invention relates to a large format camera, belonging to the field of professional photographic imaging equipment. Background Technology

[0002] Large format cameras, due to their high image quality and modular design, are widely used in professional photography, especially in landscape and architectural scenes that require precise composition and flexible adjustments. Different viewfinder backs (such as digital backs and film backs) are often needed to adapt to shooting requirements. However, the longer the time between viewfinder back replacements, the greater the risk of missing the best shooting opportunity, such as in scenes with rapidly changing light (such as dusk or fleeting weather). Summary of the Invention

[0003] The purpose of this invention is to provide a large format camera that allows for quick disassembly and replacement of the rear viewfinder assembly.

[0004] The present invention is achieved through the following technical solution.

[0005] A large format camera includes a base, a front lens assembly disposed at the front of the base and adjustable in position, a connecting bridge connected to the rear of the base and suspended above the base, a rear viewfinder assembly detachably connected to the connecting bridge by threaded fasteners, and a bellows detachably connecting the front lens assembly and the rear viewfinder assembly.

[0006] The connecting bridge has a support surface for supporting the rear viewfinder assembly and a vertically penetrating lower threaded hole. The bottom of the rear viewfinder assembly has an upper threaded hole corresponding to the lower threaded hole and is a blind hole. The threaded fastener is threadedly engaged with the upper and lower threaded holes. The bottom end of the threaded fastener has a nut. When the nut is turned, the threaded fastener descends and disengages from the upper threaded hole. The suspension height of the connecting bridge is suitable so that when the nut is supported on the base, part of the threaded fastener is located in the lower threaded hole. The base has a vertically penetrating guide hole corresponding to the portion of the threaded fastener to allow a screw for turning the nut to slide upward through it.

[0007] As a further improvement of the present invention, the supporting surface of the connecting bridge is provided with at least one vertically protruding locking post on each side of the lower threaded hole, and the bottom of the rear viewfinder assembly has a locking hole at the position corresponding to the locking post, and the locking post and the locking hole are inserted into each other.

[0008] As a further improvement of the present invention, the connecting bridge has a protruding positioning wall at the front of its support surface and extending in the left-right direction. The positioning wall has an abutting wall surface that abuts against the front of the rear viewfinder assembly, for positioning the rear viewfinder assembly at the front-rear position on the support surface.

[0009] As a further improvement of the present invention, the positioning wall has at least one interrupted portion and forms a positioning slot; the front of the rear viewfinder assembly corresponding to the positioning slot has a forward-protruding protrusion structure, and the positioning slot and the protrusion structure are inserted and engaged to position the rear viewfinder assembly on the support surface.

[0010] As a further improvement of the present invention, the supporting surface has a recessed hole for setting the locking post, and an elastic element is provided in the recessed hole to support the bottom of the locking post and the bottom of the recessed hole; the locking post can retract into the recessed hole and be hidden under the supporting surface when under pressure, and the elastic element is used to provide elastic force so that the locking post pops out and protrudes from the supporting surface when not under pressure.

[0011] As a further improvement of the present invention, magnetic components that attract each other are respectively provided inside the positioning wall and the rear viewfinder assembly.

[0012] As a further improvement of the invention, the swivel is provided by a threaded screwdriver that matches the nut.

[0013] As a further improvement of the present invention, the bottom of the base is provided with a positioning cylinder surrounding the lower threaded hole, and a cap is slidably sleeved on the outside of the positioning cylinder. The bottom of the cap is provided with a rotating rod passing through a guide hole. The cap and the rotating rod are defined by a lowest horizontal position. When the rotating rod turns the nut to lower the threaded fastener and disengage it from the upper threaded hole, the cap and the rotating rod reach their lowest horizontal position.

[0014] As a further improvement of the present invention, the positioning cylinder has a limiting plate that allows the rotating rod to pass through, and the portion of the rotating rod located between the base and the limiting plate is provided with a limiting member that can abut against the limiting plate, and when the limiting member abuts against the limiting plate, the cap and the rotating rod are in the lowest horizontal position.

[0015] As a further improvement of the present invention, the base is provided with a slide rail extending forward and backward, and a sliding bracket with an adjustable position is provided on the slide rail, and the front lens assembly is mounted on the sliding bracket.

[0016] The beneficial effects of this invention are:

[0017] By incorporating a detachable connection structure between the connecting bridge and the rear viewfinder assembly, this large-format camera can flexibly adapt to various functional or sized rear viewfinder assemblies. This solution simplifies structural complexity through a single threaded fastener connection, allowing users to quickly switch between different rear viewfinder assemblies according to shooting scene requirements. For example, in rapidly changing lighting conditions like sunset, users do not need to spend significant time adjusting or re-fixing the rear viewfinder assembly; they can complete the replacement simply by operating a single connection point. This significantly shortens the time interval between switching between different viewfinder modules, preventing missed shooting opportunities due to time delays.

[0018] The guide hole design on the base allows 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 process. In traditional disassembly, users need to repeatedly adjust the alignment of the rotating rod and the nut. This solution, however, uses the guide hole to axially limit the rotating rod, directly guiding it to contact the nut and eliminating the possibility of alignment deviation. Simultaneously, the threaded fastener remains partially retained in the lower threaded hole of the connecting bridge during disassembly, avoiding the tedious steps of reinstallation or recalibration after the threads have disengaged. This design ensures instantaneous response during disassembly and preserves a preset thread engagement starting point for subsequent installation, further reducing overall replacement time.

[0019] The double-threaded engagement of a single threaded fastener with both upper and lower threaded holes simplifies the connection structure while enhancing connection strength through the dual friction of the upper and lower threaded meshing surfaces, compensating for the potential instability of single-point fixing. Although the double-threaded engagement increases the rotational resistance of the threaded fastener, the rigid constraint of the guide hole on the rotating rod ensures that the rod always applies force in a vertical direction during operation, avoiding thread misalignment or jamming caused by axial deviation of the rotating rod. This precise guiding mechanism effectively offsets the impact of double-threaded friction on operational efficiency, allowing users to maintain a stable force direction during rapid assembly and disassembly, avoiding additional time loss due to sudden changes in resistance or operational errors, ultimately achieving a balanced optimization of connection strength and operational efficiency. Attached Figure Description

[0020] The preferred embodiments of the present invention will now be described in detail with reference to the accompanying drawings to aid in understanding the objectives and advantages of the present invention, wherein:

[0021] Figure 1 A schematic diagram of a large format camera;

[0022] Figure 2 A schematic diagram of the connecting bridge and the rear viewfinder assembly from one perspective;

[0023] Figure 3 A schematic diagram of the connecting bridge and the rear viewfinder assembly from another perspective;

[0024] Figure 4 This is a schematic diagram of the connecting bridge structure;

[0025] Figure 5 A schematic diagram of the rear viewfinder assembly;

[0026] Figure 6 This is a cross-sectional view of the locking post;

[0027] Figure 7 This is a cross-sectional view of the base of the rotating rod in the second embodiment. Detailed Implementation

[0028] The present invention will now be described in further detail with reference to the accompanying drawings and embodiments.

[0029] The directional terms such as up, down, left, right, front, back, front, back, top, and bottom mentioned or possibly used in this specification are defined relative to the construction shown in the accompanying drawings. The terms "inner" and "outer" refer to directions toward or away from the geometric center of a specific component, respectively. These are relative concepts and may therefore vary depending on their location and usage. Therefore, these or other directional terms should not be interpreted as restrictive.

[0030] A large format camera, reference Figures 1-7 It includes a base 1, a front lens assembly 2 located at the front of the base 1 and adjustable in position, a connecting bridge 3 connected to the rear of the base 1 and suspended above the base 1, a rear viewfinder assembly 4 detachably connected to the connecting bridge 3 by threaded fasteners 5, and a bellows (not shown in the figure) detachably connecting the front lens assembly 2 and the rear viewfinder assembly 4.

[0031] The connecting bridge 3 is connected to the left and right sides of the rear of the base 1, respectively, so that its body is suspended above the base 1 in a horizontal position. 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 lower threaded hole h2 is located in the middle 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 is a blind hole. The threaded fastener 5 is threadedly engaged with both the upper threaded hole h1 and the lower threaded hole h2 to realize the connection 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 so that the threaded fastener 5 can fall down and disengage from the upper threaded hole h1, thus realizing the removal of the rear viewfinder assembly 4 from the connecting bridge 3. The suspension height of the connecting bridge 3 is suitable so that when the nut 51 is supported on the base 1, part of the threaded fastener 5 is located inside the lower threaded hole h2, ensuring that the threaded fastener 5 will never disengage from the lower threaded hole h2 when the rear viewfinder assembly 4 is removed. The base 1 has a vertically penetrating guide hole h3 corresponding to the portion of the threaded fastener 5, allowing the screw rod 63 used to tighten the nut 51 to slide upward through it, and due to the sliding passage, the axial direction of the screw rod 63 will never deviate during the tightening of the nut 51.

[0032] By incorporating a detachable connection structure between the connecting bridge 3 and the rear viewfinder assembly 4, this large format camera can flexibly adapt to various functions or specifications of the rear viewfinder assembly 4. In traditional designs, the rear viewfinder assembly 4 typically requires complex fixing structures or tools for assembly and disassembly. This solution simplifies the structural complexity through a single threaded fastener 5, allowing users to quickly switch between different rear viewfinder assemblies according to shooting scene requirements. For example, in a rapidly changing sunset scene, users do not need to spend a lot of time adjusting or re-fixing the rear viewfinder assembly; they only need to operate a single connection point to complete the replacement, significantly shortening the interval between switching between different viewfinder modules and avoiding missing the best shooting opportunity due to time delays.

[0033] The guide hole h3 on the base 1 allows the rotating rod 63 to quickly penetrate the base 1 along a fixed path and align with the nut 51 of the threaded fastener 5, achieving precise guidance for the disassembly process. In traditional disassembly, users need to repeatedly adjust the alignment of the rotating rod 63 and the nut 51. This solution, however, uses the guide hole h3 to axially limit the rotating rod 63, directly guiding it to contact the nut 51, eliminating the possibility of alignment deviation. Simultaneously, the threaded fastener 5 remains partially retained in the lower threaded hole h2 of the connecting bridge 3 during disassembly, avoiding the tedious steps of reinstallation or recalibration after thread disengagement. This design ensures instantaneous response during disassembly and preserves a preset thread engagement starting point for subsequent installation, further reducing overall replacement time.

[0034] The double-threaded engagement of a single threaded fastener 5 with the upper threaded hole h1 and the lower threaded hole h2 simplifies the connection structure while enhancing the connection strength through the dual friction of the upper and lower thread meshing surfaces, thus compensating for the potential instability of single-point fixing. Although the double-threaded engagement 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 axial deviation of the rotating rod 63. This precise guiding mechanism effectively offsets the impact of double-threaded friction on operating efficiency, allowing users to maintain a stable force direction during rapid assembly and disassembly, avoiding additional time loss due to sudden changes in resistance or operational errors, ultimately achieving a balanced optimization of connection strength and operating efficiency.

[0035] In this embodiment, at least one locking post 32 is provided on each side of the support surface 31 of the connecting bridge 3, located on the lower threaded hole h2. 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 location of the locking post 32, and the locking post 32 and the locking hole h4 are inserted into each other. The insertion and engagement of the locking post 32 and the locking hole h4, through physical locking, forcibly constrains the relative position of the rear viewfinder assembly 4 and the connecting 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 makes the upper threaded hole h1 and the lower threaded hole h2 precisely aligned, avoiding the risk of repeated tightening or thread damage caused by thread misalignment, allowing the threaded fastener 5 to be screwed into the upper threaded hole h1 quickly and smoothly, further reducing the replacement time of the rear viewfinder assembly 4. Furthermore, the insertion and engagement of the locking pin 32 with the locking hole h4, based on the single-threaded fastener 5 connection, forms an additional mechanical support structure. This effectively disperses the lateral or rotational forces experienced by the rear viewfinder assembly 4 during use. Since the connecting bridge 3 and the rear viewfinder assembly 4 are fixed only by a single threaded fastener 5, their torsional resistance may be limited by the friction of the threaded meshing surface. After the locking pin 32 is inserted into the locking hole h4, the contact between the side wall of the pin and the hole wall allows it to directly withstand the lateral load caused by external forces, reducing the risk of the threaded fastener 5 loosening due to uneven stress during dynamic use. This dual connection mechanism maintains the convenience of quick assembly and disassembly while distributing the load of the threaded connection through the insertion structure, making the overall connection more stable. It avoids the need for repeated adjustments due to component wobbling caused by insufficient connection strength, thereby indirectly shortening the additional operation time caused by stability issues.

[0036] In this embodiment, the connecting bridge 3 has a protruding positioning wall 33 extending in the left-right direction at the front of its supporting surface 31. The positioning wall 33 has an abutting wall surface 331 that abuts against the front of the rear viewfinder assembly 4, used to position 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. The front of the rear viewfinder assembly 4 has a forward-protruding protrusion 41 corresponding to the positioning slot 34. The positioning slot 34 and the protrusion 41 are inserted into each other to position the rear viewfinder assembly 4 on the supporting surface 31.

[0037] The positioning wall 33's abutting surface 331 physically blocks the front of the rear viewfinder assembly 4, forcibly constraining its front-to-back position on the support surface 31. In traditional installation, the user needs to manually adjust the front-to-back alignment of the rear viewfinder assembly 4 to ensure the threaded holes are aligned. The abutting action of the positioning wall 33 causes the rear assembly to automatically conform to the preset front-to-back reference position during placement. This eliminates the need for manual fine-tuning in the front-to-back direction during installation and avoids situations where threaded holes cannot mesh due to front-to-back deviation. The insertion and engagement of the positioning slot 34 and the protruding structure 41 precisely constrains the left-to-right position of the rear viewfinder assembly 4 through lateral limiting. The slot formed by the interrupted portion of the positioning wall 33 and the protrusion on the assembly form a "mortise and tenon" fit, forcibly guiding the rear viewfinder assembly 4 to the preset lateral reference point when moving left and right. This mechanical insertion ensures that the alignment tolerance of the threaded holes in the left-to-right direction approaches zero.

[0038] The synergistic effect of the positioning wall 33 and the slot creates dual physical constraints in both front-to-back and left-to-right dimensions, working in conjunction with the vertical insertion of the original locking post 32 to construct a three-dimensional positioning system. This system allows the rear assembly to quickly and accurately reach the preset three-dimensional spatial coordinates during installation, ensuring complete alignment of the upper and lower threaded holes h2. Simultaneously, the multi-dimensional mechanical constraints disperse the force direction of the rear assembly during use. For example, the contact wall 331 resists the forward and backward thrust during shooting operations, while the slot and protrusion suppress lateral torsional forces, thereby reducing the risk of loosening due to external forces. This design shortens installation time through precise positioning and reduces the need for secondary adjustments due to insufficient stability during use through multi-dimensional reinforcement, ultimately achieving simultaneous optimization of replacement efficiency and connection reliability.

[0039] In this embodiment, the support surface 31 has a recessed hole h5 for setting the locking post 32. An elastic element 321 is provided within the recessed hole h5 to support the bottom of the locking post 32 and the bottom of the hole h5. Under pressure, the locking post 32 can retract into the recessed hole h5 and be concealed beneath the support surface 31. The elastic element 321 provides elastic force so that the locking post 32 protrudes from the support surface 31 under non-pressure conditions. More specifically, a vertical guide post 322 is provided within the recessed hole h5. The locking post 32 is inserted into the guide post 322 and can slide up and down. The elastic element 321 is a spring and is arranged around the guide post 322.

[0040] The retractable and pop-out locking post 32 allows the rear viewfinder assembly 4 to be temporarily pressed into the recessed hole h5 during initial placement, eliminating the physical obstruction of the assembly's movement caused by its protrusion. Otherwise, the assembly's movement would be blocked by the locking post 32, preventing the adjustment of its position. The retractable and pop-out locking post 32 allows the user to press the assembly directly onto the support surface 31 without precise pre-positioning, and then freely adjust it to the preset position against the wall surface 331 and the positioning slot 34. This process greatly reduces the precision requirements for initial placement and simplifies the operation steps. The automatic reset feature of the elastic element 321 ensures that after the rear viewfinder assembly 4 is adjusted into place, the locking post 32 immediately pops out and precisely engages with the locking hole h4. When the rear viewfinder assembly 4 completes its 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 post 32. At this point, the elastic force of the elastic element 321 pushes the locking post 32 up to a non-pressurized state, achieving "passive locking." This mechanism requires no additional operation, avoiding interruptions to the installation process due to distraction while operating the locking post 32, and ensuring connection stability through physical self-locking characteristics. Furthermore, the "avoid first, lock later" feature of the elastic locking post 32, in collaboration with the positioning wall 33 and the slot, breaks down the installation process into three efficient steps: "rough placement → fine-tuning positioning → automatic locking." This phased operation mode significantly simplifies the user's operational complexity through physical guidance.

[0041] In this embodiment, the positioning wall 33 and the rear viewfinder assembly 4 are respectively provided with mutually magnetic components (not shown in the figure); more specifically, the positioning wall 33 located on both sides of the positioning slot 34 and the left and right parts of the rear viewfinder assembly 4 are provided with mutually magnetic components.

[0042] When the rear viewfinder component 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 need for manual coarse adjustment in the front and back directions. The magnetic attraction effect allows the component to be attracted to a position close to the target position the moment it contacts the support surface 31, and only slight pressure or release is needed to complete the front and back bonding.

[0043] The symmetrical distribution of the magnetic components on the left and right sides forms a horizontal magnetic balance, guiding the rear viewfinder component to automatically converge towards the center of the positioning slot 34 when moving left and right. When the component is magnetically attracted to the wall 331, the left and right magnetic forces form a "centripetal force", allowing the user to feel the magnetic guidance when finely adjusting the rear viewfinder component 4 left and right. The user can feel the alignment trend between the protruding structure 41 and the slot by simply pushing the component. When the user slides the component left and right, the magnetic force will naturally reduce the resistance when it deviates from the center, and enhance the attraction when it is close to the slot, just like physical tactile feedback, which helps to quickly position and reduce the trial and error cost of left and right calibration.

[0044] The synergistic effect of magnetic attraction and mechanical positioning structures forms a two-stage, highly efficient mode of "magnetic pre-positioning + mechanical precision positioning." After the magnetic attraction completes the large-scale spatial guidance of the component, the rigid structure of the positioning wall 33 and the slot is responsible for the final precise positioning, with a clear division of labor between the two. For example, when the component is magnetically attracted to the vicinity of the contact wall 331, there may still be millimeter-level deviations. At this time, the user only needs to slide slightly left or right along the magnetic guide, and the protruding structure 41 will be guided to the fully inserted state by both magnetic force and the physical positioning of the slot. This mechanism utilizes the rapid response characteristics of magnetic attraction to cover the coarse adjustment stage, while retaining the mechanical structure's control capability for micron-level precision, thus shortening the overall process time from placement to locking.

[0045] In the first implementation, the screw rod 63 is provided by a threaded screwdriver that matches the nut 51. The threaded screwdriver is an external tool, such as a screwdriver or a hex wrench. Since the threaded screwdriver is an external tool, the user can choose a suitable model based on existing equipment, reducing design complexity and manufacturing costs. However, in actual rapid disassembly scenarios, the operator needs to carry additional tools and complete a multi-step process of "taking the tool → aligning the guide hole h3 → inserting the screw rod 63 → tightening the nut 51".

[0046] In the second embodiment, the bottom of the base 1 is provided with a positioning cylinder 61 surrounding the lower threaded hole h2. A cap 62 is slidably sleeved on the outside of the positioning cylinder 61. The bottom of the cap 62 is provided with a rotating rod 63 passing through the guide hole h3. The cap 62 and the rotating rod 63 are defined by the lowest horizontal position. When the rotating rod 63 turns the nut 51 to make the threaded fastener 5 descend and disengage from the upper threaded hole h1, the cap 62 and the rotating rod 63 reach their lowest horizontal position.

[0047] By integrating the cap 62, the lever 63, and the base 1 into a linked structure, tool-free, integrated, and rapid operation is achieved. The cap 62 and lever 63, as inherent components of the base 1, maintain a spatial connection with the nut 51. During disassembly, the user only needs to push the cap 62 upwards with one hand, and the lever 63 automatically aligns with the nut 51 through the axial constraint of the guide hole h3, eliminating the need for external tool alignment and insertion. The sliding fit between the cap 62 and the positioning cylinder 61 limits the lowest horizontal position of the lever 63. When the cap 62 is rotated to the lowest horizontal position, the threaded fastener 5 is completely disengaged from the upper threaded hole h1, and the rear viewfinder assembly 4 is instantly unlocked. This setting replaces the traditional manual judgment of tightness with a physical limit, avoiding thread wear or incomplete disassembly caused by excessive tightening. The user only needs to rotate the cap 62 to a position where it cannot be pressed down further to ensure that the threaded fastener 5 is completely disengaged, eliminating redundant steps of repeatedly verifying the disassembly status. In addition, the pushing and rotating action of the cap 62 is a continuous one-way operation. When the user pushes the cap 62 upward, the top of the lever 63 automatically tightens the nut 51; then, rotating the cap 62 clockwise will simultaneously complete the tightening of the nut 51 and the lowering of the threaded fastener 5. The whole process does not require switching gestures or adjusting the direction of force, and the smoothness of operation is significantly better than the step-by-step operation of external tools.

[0048] In this embodiment, the positioning cylinder 61 has a limiting plate 611 that allows the rotating rod 63 to pass through. The portion of the rotating rod located between the base 1 and the limiting plate 611 is provided with a limiting member 631 that can abut against the limiting plate 611. When the limiting member 631 abuts against the limiting plate 611, the cap 62 and the rotating rod 63 are in the lowest horizontal position.

[0049] In this embodiment, the base 1 is provided with a slide rail 11 extending forward and backward, and a sliding bracket 12 with an adjustable position is provided on the slide rail 11. The front lens assembly 2 is mounted on the sliding bracket 12. A knob is provided on the side of the base 1 to control the forward and backward position of the sliding bracket 12. The user can adjust the forward and backward position of the front lens assembly 2 by rotating the knob.

[0050] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A large format camera, characterized in that, Suitable for scenes with rapidly changing light, it includes a base (1), a front lens assembly (2) located at the front of the base (1) and adjustable in position, a connecting bridge (3) connected to the rear of the base (1) and 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 detachably connected to 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 is 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). When the nut (51) is turned, the threaded fastener (5) can descend and disengage from the upper threaded hole (h1). The suspension height of the connecting bridge (3) is suitable so that when the nut (51) is supported on the base (1), part of the threaded fastener (5) is located in the lower threaded hole (h2). The base (1) has a vertically penetrating guide hole (h3) at the part corresponding to the threaded fastener (5) to allow the screw rod (63) used to turn the nut (51) to slide upward through. The connecting bridge (3) has a protruding positioning wall (33) on the front of its support surface (31) that extends in the left and right direction. The positioning wall (33) has an abutting wall (331) that abuts against the front of the rear viewfinder assembly (4) for positioning the rear viewfinder assembly (4) on the support surface (31). The positioning wall (33) and the rear viewfinder assembly (4) are respectively provided with magnetic components that attract each other. The positioning wall (33) has at least one interrupted part and forms a positioning slot (34). The front of the rear viewfinder assembly (4) corresponding to the positioning slot (34) has a forward-protruding protrusion structure (41). The positioning slot (34) and the protrusion structure (41) are inserted and fitted together for positioning the left and right position of the rear viewfinder assembly (4) on the support surface (31). The supporting surface (31) of the connecting bridge (3) is provided with at least one recess (h5) on both sides of the lower threaded hole (h2). A locking post (32) is provided in the recess (h5). The bottom of the rear viewfinder assembly (4) has a locking hole (h4) at the position corresponding to the locking post (32). An elastic element (321) is provided in the recess (h5) to support the bottom of the locking post (32) and the bottom of the recess (h5). The locking post (32) can be retracted into the recess (h5) and hidden under the supporting surface (31) when under pressure. The elastic element (321) is used to provide elastic force so that the locking post (32) pops out when not under pressure and is protruded from the supporting surface (31) and inserted into the locking hole (h4).

2. The large format camera according to claim 1, characterized in that, The swivel (63) is provided by a threaded screwdriver that matches the nut (51).

3. The large format camera according to claim 1, characterized in that, The base (1) has a positioning cylinder (61) surrounding the lower threaded hole (h2) at its bottom. A cap (62) is slidably sleeved on the positioning cylinder (61). The bottom of the cap (62) has a rotating rod (63) passing through the guide hole (h3). The cap (62) and the rotating rod (63) define a minimum horizontal position. When the rotating rod (63) turns the nut (51) so that the threaded fastener (5) descends and disengages from the upper threaded hole (h1), the cap (62) and the rotating rod (63) reach their minimum horizontal position.

4. The large format camera according to claim 3, characterized in that, The positioning cylinder (61) has a limiting plate (611) that allows the rotating rod (63) to pass through. The portion of the rotating rod (63) located between the base (1) and the limiting plate (611) is provided with a limiting member (631) that can abut against the limiting plate (611). When the limiting member (631) abuts against the limiting plate (611), the cap (62) and the rotating rod (63) are in the lowest horizontal position.

5. The large format camera according to any one of claims 1-4, characterized in that, The base (1) is provided with a slide rail (11) extending forward and backward, and a sliding frame (12) with adjustable position is provided on the slide rail (11). The front lens assembly (2) is mounted on the sliding frame (12).

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