Camera Mounting Arrangement

The present invention relates to an arrangement for displacing a camera along a track, the camera being mounted on a carriage movable along the track.

The prior art includes two main types of such arrangements. The one type, widely used within the movie production industry, has a rail track resting on the ground or on some other stationary surface. According to the second type the track consists of a beam supported at its both ends.

This invention starts from devices of the last-mentioned type and has as its main purpose to increase the usefulness of such devices by making the track movable in two dimensions, rotatable and tiltable. A second object of the invention is to provide an arrangement of the type mentioned where the beam does not require any end supports. The result of the beam ends being free is that the possibilities to position the camera relatively the subject are considerably increased. Those and other objects of the invention as well as advantages accompanying it have, according to its main characteristic, been achieved in the following way. The camera carriage is in such a way connected to a counterweight, also displaceable along the track, that upon a change of the camera position relatively the center of the beam, as counted in its longitudinal direction, the counterweight is displaced in the opposite direction. The result of this arrangement is that the camera carriage and the counterweight are kept statically balanced relatively the center where the beam is mounted on a support.

One embodiment of the invention will now be described, reference being made to the accompanying drawing.

FIG. 1 does diagrammatically illustrate the principle of the invention.

FIG. 2 is a partial perspective view showing a track in the form of a box beam and illustrating one way of designing the counterweight.

FIG. 3 shows a camera carriage with rollers cooperating with flanges of the girder beam.

Reference numeral 1 designates a track in the shape of a box beam or hollow box girder housing a counterweight 6 supported by a camera stand, a so-called tripod. The beam is supported at its center, counted in the longitudinal direction. A camera 3 mounted on a carriage 4 can travel along the track 1 through cooperation between rollers 10 at flanges of the beam. The camera carriage is, by means of an endless wire 5 or the like running over pulleys 7, 8 at each of the track ends, in such a way connected with the counterweight 6 that, upon displacement of the carriage 4 in either direction, the counterweight 6 will be displaced in the opposite direction. In the embodiment shown the counterweight is likewise mounted on a carriage. The arrangement is such that in any position of the camera along the beam its distance from the beam center will be the same as that of the counterweight carriage 6. Also, the mass of the counterweight should correspond to the combined mass of the camera and the camera carriage. This arrangement means that the beam and its loads will always be maintained statically balanced independently of the position of the camera. This has in turn made it possible to replace the prior art beam end supports with a single, centrally located standard type stand, a tripod. The structure described offers great advantages in terms of the possibilities of bringing the camera in an optimum position close to the subject. The track 1 is movable in two dimensions, it can be turned around the stand 2 in a horizontal plane and it can be tilted in the vertical plane. As is understood, these two movements can be carried out simultaneously. Another important advantage is that, thanks to the fact that both ends of the beam are free, it becomes possible to put the camera in a position much closer the subject than what could be achieved according to the prior art. By way of example, a free beam end can be protruded over e.g. a table or inserted through an opening, for example a window, making it possible to film subjects at the other side of the opening.

The counterweight may consist of two or more parts which may be held together by e.g. longitudinal bolts having nuts at their ends. The number and thickness of the counterweight parts may be varied for the purpose of matching the mass of the counterweight to the sum of the masses of the camera carriage and the camera used in any given situation.