GB2580020A

GB2580020A - A camera assembly and a kit of parts therefor

Info

Publication number: GB2580020A
Application number: GB1819423.3A
Authority: GB
Inventors: James Coughlan Benjamin
Original assignee: Individual
Current assignee: Individual
Priority date: 2018-11-29
Filing date: 2018-11-29
Publication date: 2020-07-15
Anticipated expiration: 2038-11-29
Also published as: GB2580020B; DE112019005960T5; GB201819423D0; WO2020109809A1

Abstract

A camera assembly includes a camera body 1 and a lens 2 which has a proximal portion 10 fixed to the camera body and a distal portion 11 that rotates with respect to the proximal portion to change the focus of the lens. A matte box 3 is attached at a distal end of the distal portion of the lens so that the matte box moves axially and also rotates with respect to the distal portion. An anti-rotation device 4 & 7, figure 4 bridges the matte box 3 and the camera body 1 and/or the proximal portion of the lens so as to allow the distal portion of the lens to rotate without rotating the matte box. A kit of parts attaches to a matte box and a camera body and/or a camera lens. The kit has a rotary bearing with two rotating parts one attaching to the matte box the other attaching to a second portion of a camera lens. The kit also includes an anti-rotation device mounted to the matte box and the camera body and/or a first portion of the camera lens and a bridging portion connecting two mounting brackets to prevent their relative rotation.

Description

A CAMERA ASSEMBLY AND A KIT OF PARTS THEREFOR

The present invention relates to a camera assembly and a kit of parts therefor.

In particular, it relates to a camera assembly comprising a camera body; a lens having a proximal portion fixed to the camera body and a distal portion rotatable with respect to the camera body to change the focus or focal length of the lens; and a matte box attached to the distal portion of the lens.

Matte boxes are well-known in the art of photography and video. Their main purpose is to prevent lens flare and glare on the camera lens. The matte box is typically adjustable either via a bellows arrangement or by a number of pivotal flaps which can be adjusted to cater for the viewing angle of the lens and/or the nature of the incident light.

There is a problem within the film industry, particularly when using older lenses such as anamorphic lenses with a matte box. The matte box is clamped or 'clipped' onto the distal end of the lens. However, when the distal end of the lens is rotated with respect to the main body, the matte box will rotate with the lens meaning that such an arrangement is impractical as the camera is generally fixed and cannot therefore be rotated to compensate for the rotation of the matte box.

This problem is traditionally dealt with by mounting the matte box on rails which are attached to the camera body. The lens is then free to move axially with respect to the matte box. This creates a variable gap between the distal end of the lens and the matte box which can vary by as much as 5cm. In order to prevent light entering this gap, a flexible "donut" is mounted between the matte box and the lens. However, as this is required to flex to a considerable extent, it will often pop off in use. Further, as the lens is movable with respect to the matte box, it can come into contact with the filter held within the matte box thereby damaging the lens, filter or mounting.

The present invention is directed at solving this problem.

According to a first aspect of the present invention there is provided a camera assembly according to claim 1.

The combination of the rotatable mounting between the matte box and the distal portion of the lens together with the anti-rotation device prevents the matte box from being rotated when the distal end of the lens is rotated in order to focus the camera. The matte box will simply undergo an axial movement in commensurate with the axial translation of the distal portion of the lens with respect to the proximal end. This allows the use of a clamp-on, or clip on matte box with a camera in situations where this was previously impractical for the reasons set out above.

The rotatable mounting of the matte box to the distal portion of the lens could simply be a friction fit which allows relative rotation. However, preferably, a rotary bearing is provided, the rotary bearing comprises two parts rotatable with respect to one another, one part being attachable to the matte box and the other part being attachable to the distal portion of the lens. This provides a more reliable rotatory mounting between the matte box and the lens.

The anti-rotation device may take any form which will prevent the matte box from rotating as the distal portion of the lens is rotated. Preferably the anti-rotation device comprises a first mounting bracket for mounting to the matte box, a second mounting bracket for mounting to the camera body and/or a first portion of the camera lens, and a bridging portion connecting the two brackets.

The second mounting bracket may be configured to be attached to one side of the first portion of the camera lens. However, preferably, the second bracket comprises a plate with a central orifice to receive the first portion of the camera lens and/or the camera body, and an attachment for the bridging portion being radially offset from the central orifice.

The bridging portion may be any component which can link the two mounting brackets.

However, preferably, it is in the form of rod extending between the two brackets. The second mounting bracket can be mounted to the camera body and/or a first portion of the lens.

The rod will be axially moved upon relative axial displacement of the two parts of the lens. It is therefore preferably mounted such that there is adequate clearance for the full range of axial movement of a proximal end of the rod. Alternatively, the rod may be a telescopic rod, in which case it may be mounted at its distal end on the front face of the camera body. The camera may be any type of camera where the lens has proximal and distal portions which are rotatable with respect to one another to change the focus or focal length of the lens. However, preferably, the lens is an anamorphic lens.

The matte box is preferably a clamp-on matte box (also referred to as a clip-on matte box). This refers to a matte box which is mounted on the distal end of the lens, rather than being mounted to a support system consisting of two 15mm or 19mm rails that are mounted underneath the camera.

According to a second aspect of the present invention, there is provided a kit of parts according to claim 9.

The kit according to the second aspect of the present invention will incorporate one or more of the preferable features of the first aspect of the invention.

An example of a camera assembly and kit in accordance with the present invention will now be described with reference to the accompanying drawings. In which: Figs. 1 to 4 are perspective views of the camera, lens and matte box showing an assembly process in which the various components of the kit are progressively attached, culminating in Fig. 4 which is the completed assembly; and Fig. 5 is partial cross-section of a portion of the assembly taken in a plane passing through the bridging rod as shown in Fig. 4.

The assembly consists of three conventional components, namely a camera 1, lens 2 and matte box 3. To these are added a bearing assembly 4, front bracket 5, rear bracket 6 with a bridging rod 7 connecting a front 5 and rear 6 brackets. This assembly is described in greater detail below.

The camera 1, lens 2 and matte box 3 are conventional camera components. Indeed, the whole point of the present invention is that it can be applied to existing camera configurations. The lens 2 has a proximal portion 10 which attaches to the camera body 1 4 -via a conventional mounting and a distal portion 11 rotatable with respect to the proximal portion to change the focus or focal length of the lens.

The matte box 3 is a clip-on matte box which is traditionally clipped onto the end of the distal portion 11 of the camera lens 2 in order to reduce unwanted incident light on the lens.

The matte box 3 is provided with a number of adjustable removable components in order to meet the specific light requirements in any given situation. If the matte box 3 mounted directly to the lens 2, rotation of the distal portion 11 would cause rotation of the matte box which makes such a system impractical in use as the rotational angle of the matte box 3 with respect to the image needs to be preserved.

The present invention prevents this from occurring as described below.

A bearing 4 comprising a main bearing ring 12 and a clamping ring 13 these have approximately the same internal diameter as the external diameter of the distal portion 11 of the lens. These are fitted over the distal portion 11 of the lens as shown in Figs. 1, 2 and 5. Grub screws secure the bearing ring 12 in place and these bear against the clamping ring 13 to avoid damaging the lens casing. The bearing ring 12 has an outer portion 14 and an inner portion 15 which are rotationally supported with respect to one another via a plurality of ball bearings 16 in a manner well known in the art. The outer portion 14 has a thinned walled portion 17 which extends to the distal end of the lens 2 ending in a radially inwardly extending lip 18. The thinner wall portion 17 is the part engaged by the matte box 3 and, in view of its thin wall, it allows the matte box 3 to be fitted to the lens 2 without requiring additional modification of either component.

The above described bearing is particularly suited to an arrangement where the inner diameter of the mounting portion of the matte box 3 is very close to the outer diameter of the distal end of the lens 2. For example, a common lens size is one with a 141mm outer diameter, while the orifice on the matte box is 143mm. There is therefore only 1mm of clearance around the lens. Under these circumstances, the use of the thinner wall portion 17 which is axially offset with respect to the bearing is used. More commonly, lenses have an outer diameter of 110mm and the matte box has an inner diameter of 125mm. Under these circumstances, there is no need for the mounting portion to be axially offset with respect to the bearing as the matte box can simply be mounted to the outside of the bearing.

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It is currently our intention to sell a kit comprising a number of bearing rings, the majority of which are designed to fit with an outer diameter of 110mm on the lens 2. These do not have the bearing offset from the mounting portion. There will then be one which is designed to fit with a 141mm outer diameter lens which has the thinner wall portion 17 arrangement illustrated in Fig. 5. Typically a user will have four separate lenses and this allows them to attach one bearing to each of their lenses.

With the bearing 4 in place, the matte box 3 is now free to rotate with respect to the distal portion 11 of the lens, whereas before the two components were rotatable together.

The second new part comprises the anti-rotation mechanism in the form of the front bracket 5, rear bracket 6 and bridging rod 7. The front bracket 5 is a clip-on component as best shown in Figs. 3 to 5. This has a number of teeth 20 which engage in corresponding orifices 21 in the matte box 3. Other designs of matte box do not have orifices 21 such that the bracket 5 may be attached in some other way such as a screw on fitting. The front bracket 5 is also provided with a rearwardly extending boss 22 which has a screw thread to receive a distal end of the bridging rod 7. Towards the opposite end of the bridging rod 7 is the rear bracket 6. This has a central opening 25 which receives the proximal portion 10 of the lens 2 as best shown in Figs. 2 and 3. The rear bracket 6 has a split-ring configuration to reduce any internal stresses and it is a tight fit on the proximal portion 10 of the lens 2 as shown in Figs. 3 and 4. The friction between the rear bracket 6 and the proximal end 10 of the lens 2 prevent rotation of the bracket with respect to the lens. A more positive engagement to prevent this rotation can be provided if necessary, in the form of, for example, a clamping screw which tightens the bracket 6 onto the lens 2.

As mentioned above, a user will commonly have four lenses in a set. We therefore intend to supply a kit with four rear brackets 6 each of which has an opening 25 to fit with the proximal portion 10 of the lens body. This is typically standardised at 75mm, but different sizes and/or spacers can be provided if necessary.

The bracket 6 is also provided with a radially extending arm 26 which has a small opening 27 which receives a self-aligning bearing 28 in which the bridging rod 7 is slidably received. 6 -

In order to assemble the camera assembly, the bearing 4, front bracket 5 and rear bracket 6 are attached to the various positions as described above. The bridging rod 7 is then screwed into the boss 22 and inserted into the bearing 28.

Now, when the distal portion 11 of the lens 2 is rotated to alter the focus or focal length of the lens, the bearing 4 allows this rotation while the matte box 3 is prevented from rotating by the fact that the bracket 5 is attached to the rod 7 which passes through the bearing 28. Because the rear bracket 6 cannot rotate, the bridging rod 7 cannot move in a circumferential sense about the main axis of the lens. As the distal portion 11 of the lens is rotated with respect to the proximal portion, it moves with respect to the proximal portion in an axial as well as a radial direction. This axial movement is transmitted to the matte box and hence to the bridging rod 7 which is free to move axially with respect to the rear bracket 6 by sliding through the self-aligning bearing 28. As can be seen in Fig. 4, the bridging rod 7 is offset with respect to the camera body 1 such that it is free to move axially.

It could alternatively be in alignment with the main camera body provided that sufficient room is allowed for the end of the rod to move axially without interfering with the camera body. As a further alternative the bridging rod 7 may be telescopic. 7 -

Claims

CLAIMS: 1. A camera assembly comprising: a camera body; a lens having a proximal portion fixed to the camera body and a distal portion rotatable with respect to the proximal portion to change the focal length of lens; a matte box attached at a distal end of the distal portion of the lens so that the matte box is rotatable with respect to the distal portion; and an anti-rotation device bridging the matte box and the camera body and/or the proximal portion of the lens so as to allow the distal portion of the lens to rotate without rotating the matte box.
2. A camera assembly according to claim 1, further comprising a rotary bearing comprising two parts rotatable with respect to one another, one part being attachable to the matte box and the other part being attachable to the distal portion of the lens.
3. A camera assembly according to claim 2, wherein the rotary bearing comprises the bearing portion and a mounting portion, the mounting portion having a smaller outer diameter than the bearing portion and being offset in an axial direction from the bearing portion.
4. A camera assembly according to any preceding claim, wherein the anti-rotation device comprises a first mounting bracket for mounting to the matte box, a second mounting bracket for mounting to the camera body and/or a first portion of the camera lens, and a bridging portion connecting the two brackets.
5. A camera assembly according to claim 4, wherein the second bracket comprises a plate with a central orifice to receive the first portion of the camera lens and/or the camera body, and an attachment for the bridging portion being radially offset from the central orifice.
6. A camera assembly according to claim 4 or claim 5, wherein the bridging portion is a rod extending between the two brackets. 8 -
7. A camera assembly according to any preceding claim, wherein the lens is an anamorphic lens.
8. An assembly according to any one of preceding claims, wherein the matte box is a clamp-on matte box.
9. A kit of parts attachable to a matte box and a camera body and/or a camera lens, the kit comprising: a rotary bearing comprising two parts rotatable with respect to one another, one part being attachable to the matte box and the other part being attachable to a second portion of a camera lens, which is rotatable with respect to the first portion: and an anti-rotation device comprising a first mounting bracket for mounting to the matte box, a second mounting bracket for mounting to the camera body and/or a first portion of the camera lens and a bridging portion connecting the two brackets to prevent relative rotation of the two brackets about the main axis of the lens.