GB2523063A

GB2523063A - Camera matte box

Info

Publication number: GB2523063A
Application number: GB1206587.6A
Authority: GB
Inventors: Andrew Subratie
Original assignee: Individual
Current assignee: Individual
Priority date: 2012-04-13
Filing date: 2012-04-13
Publication date: 2015-08-19
Anticipated expiration: 2032-04-13
Also published as: GB201206587D0; GB2523063B

Abstract

A matte box 20 for a camera, for holding a plurality of filters, includes a front element such as a sunshade 10, a side wall element or elements, and a back element 4, the front element, side means and back element together defining a volume suitable for housing one or more filters. The back element slidably engages with the side wall element or elements, so that the volume suitable for the filters may be extended.

Description

CAMERA MATTE BOX

The present specification relates to a camera matte box, that is, an assembly for shie'ding the front lens from unwanted ghre and also for holding one or more filters in front of a camera, particularly though not exclusively a motion picture camera.

Originally developed to hold mattes' to block out areas of an image, matte boxes are now more usually used to hold fillers in front of a camera tens.

They also typically incorporate a sunshade or lens hood to exclude light not from the scene being filmed. Particularly when shooting motion pictures or videos, a camera man may wish to use severa' fillers, such as colour tints, is gradated filters, uv filters or polarising filters, at the same time. The matte box is attached to or held in front of the camera's lens assembly A known type of matte box provides two side walls extending back from the sunshade, these side walls including guides for the filters to be slid into.

Filters are often provided in a standard rectangular tray for this purpose.

Since the side walls and sunshade are forward of the camera lens, the angle of view may be reduced (known as vignetting), depending on the distance from the lens and the internal diameter of the parts. Side walls having guides for three or more filter stages are used when the camera man wishes to use this many filters at once, but side walls having only two stages are also used, since they are not as long and give a wider angle of view. Although the filter trays may be removed from the side walls with comparative ease, when a camera man wishes to switch from two stage filter assembly to a three stage so that he may use more than two filters simultaneously, or wishes to switch from a three stage filter assembly to a two stage assembly so that he can achieve a wider viewing angle, disassembly of the matte box is necessary. Each side walls is typically attached to the sunshade using a pair of captive bolts that extends through the sidewall, and engages with a thread in the rear face of the sunshade. The bolt may have a head suitable for a screwdriver or an Allen key to turn. To switch filter assemblies, the two side walls of one filter assembly must be removed, each requiring the loosening of the two bolts, before the two side walls of the other filter assembly are positioned against the sunshade and each side walls pair of bolts are engaged and tightened to secure the side walls to the sunshade. The matte box is then repositioned in front of the camera lens is and filming may resume. The camera man must ensure that the different side walls are kept to hand, and the correct corresponding pairs are selected and fitted. On a movie set, the time such assembly and disassembly takes can be very costly.

The present invention aims to provide a matte box that reduces the time and complexity of switching between different numbers of filter stages. Another aim of the invention is to provide a matte box having a wide angle of view.

According to the present invention, there is provided q matte box system for a camera, for hoMing a pthrality of filters, including a front element such as a sunshade, a side wall element or elements, and a back element, the front element, side means and back element together defining a volume suitable for housing one or more filters, wherein the back element slidably engages with the side wall element or elements, so that the volume suitable for the filters may be extended.

D

The invention will now he described, by way of example, with reference to the drawings, of which Figure 1 is a side elevation of a matte box in a first position Figure 2 is a perspective view of the matte box in the first position Figure 3 is a side elevation of the matte box in a second position Figure 4 is a perspective view of the matte box in the second position Figure 5 is an exploded perspective view of the matte box in the second position.

References to forward and cognate terms such as front, are used herein to designate the direction that the camera lens receives light from and the opposite direction, and references to backward and rear designate the opposite directi on.

Referring to figures 1 and 2, the matte box 20 comprises a sunshade ID, a pair of filter holder guides 2, and a backplate 4. The back plate 4 includes a split ring clamp which is attached to the camera's lens assembly in a known manner. The filter guides 2 are attached to the sunshade, and the backplate 4 is in turn attached to the filter guides 2. The sunshade, the two filter holder guides 2 and the backplate together define a volume that is sufficient for two filter trays 12 to removably inserted, the filter holder guides including guide surfaces, and if necessary bearing means, to allow the filter trays to be smoothly slid into place, as is known in the art. Apart from this movement, the filter trays are constrained relative to the matte box. Threaded thumbwheels 7 extend through one of the filter holder guides 2, to engage against the filter trays when inserted and releasably secure them. For convenience, these thumbwheels may be vertically offset.

Referring now also to figures 3 and 4, the backplate 4 is secured to the filter holder guides 2 by screws I, each filter holder guide 2 having two such screws.

When the user of the matte box wishes to add a third filter tray, screws I are loosened to release the back plate 4, and the back plate slid backwards to create a larger volume between the sunshade, the two filter holder guides and the backplate. For this purpose, the filter holder guides feature a pair of elongate is slots 8 having rounded ends, so that the screw head can engage with the filter holder, but when loosened the shaft of the screw can move parallel to the optical axis. The ends of the slots define the extent of travel of the backplate 4 relative to the sunshade and filter holder guides. When the backplate has been pulled back as far as permitted by the screws I engagement with the slots 8, the screws are tightened to secure the new position of the backplate.

The additional volume so provided allows a third filter tray 5 to be introduced to the matte box. The back plate 4 includes threaded thumbwheels 6 which the user can tighten to engage with the side of the third filter tray 5 and secure its position.

The translation of the backplate 5 to accommodate the third filter tray increases the distance between the camera's lens assemhiy and the first filter tray and the sunshade. Depending on the inner diameters of the components, it will be seen that this may reduce the viewing angle somewhat. If the camera operator wishes to remove the third filter tray and to increase viewing angle, the operation previous'y described may be reversed, that is, the thumbwheels 6 may be loosened to allow the third filter tray to be removed, the screws 1 and loosened and the backplate moved forwards towards the sunshade, and the screws I re-tightened to secure this configuration.

Referring to figure 5, the backplate includes two male dovetail parts 3 that extend forwards towards the sunscreen. These male dovetail pans fit into slots 9 in the filter holder guides 2, these slots 9 having a corresponding female profile to the male dovetail part 3. The male dovetail parts allow translation of is the backplate back and forth along the optical axis, but constrain may other movement relative to the filter holder guides and sunshade. The screws I of the filter holder guide engage with sides of the male dovetail parts, and holes or depressions may be provided on the male dovetail parts for the screws to engage with. The thumbwheels 6 are mounted on, and extend through, the male dovetail parts. It will be seen that other interlocking profiles besides a dovetail may he provided which allow the hackplate to slide relative to the filter holder guides, though not al shapes will constrain lateral, radial or rotational movement so effectively.

It will be seen that such a system allows a very convenient and quick conversation of a two stage filter assembly to a three stage filer assembly and vice versa. Additionally, all the necessary parts are present in the assembly, so there are fewer parts to carry, and the possibility of parts getting mislaid or mixed up is obviated.

The system here describes an assembly that may be converted from two stages to three and vice versa, but the principle may be extended to other numbers of stages, depending on the depth (when considered along the optical axis) of the filter holder guides and the male dovetail parts. Also, the backplate could be moved to different discrete positions. In this manner, it would be possible to have an assembly that could expand to define volumes suitable for one, two and three filter stages. A greater depth could be provided to provide a matte box that variously provided three, four or five filter stages. Additionally, the depth of the male dovetail pans and the filter gwde holder does not have to be the same.

Although the above system includes a split donut ring that clamps to a camera lens assembly, the principles may be applied to systems that are mounted in other ways, for example on iris rods.

Claims

Claims 1. A matte box system for a camera, for holding a plurality of filters, including a front element such as a sunshade, a side wall element or elements, and a back element, the front element, side means and back element together defining a volume suitable for housing one or more filters, wherein the back &ement slidably engages with the side wall element or elements, so that the volume suitable for the filters may be extended.
2. A matte box according to claim I, wherein the side wall element or elements comprise two side walls situated either side of the optical axis.
3. A matte box according to Jaim 2 wherein the side wall elements include a female dovetail s'ot and the back dement includes two corresponding male is dovetails.
4. A matte box according to any previous claim wherein the side wall &ement or elements include engagement means that releasably secure the position of the back element relative to the side wall dement or elements.