Cinema News and Property Gazette Technical Supplement (1924-1925, 1943, 1946)

Supplement to THE CINEMA NEWS AND PROPERTY GAZETTE. July 31, 1924, NEW PRINCIPLE IN PROJECTION. OPTICAL v. MECHANICAL " INTERMITTENT. CONTINUOUS FILM TRAVEL. It is claimed by many of the leading experts in cinematography that not until the intermittent stopping and starting of the film in its travel is replaced by continuous travel will perfect projection be achieved, li that be so, then a new projector yclept the Arcadia, now being demonstrated at 27, Soho Square, W. , can be said to have solved the problem of perfect projection. The Arcadia dispenses with the Maltese cross or other intermittent movement of the film, as well as the necessity for a shutter to mask such motion. The intermittent action — as we may call it for convenience, although it is not actually so — is optical instead of mechanical. A revolving mirror receives the image from the gate aperture lenses, and projects it through a prism and through projection lenses to the top section of the mirror, where it is in turn passed on through a tele-objective lens to a projection mirror and out to the screen. As the image of one picture reaches its maximum a second is superimposed, and as the first dissolves out the second builds to maximum, and so on; so that the usual periods of intermittent dark and light give place to a natural flickerless fading in and out of the projected image. That is the revolutionary principle of the machine. There are many other interesting features. The lamp is of the mirror-arc type, but a clever clock-feed arrangement ensures automatic continuance of a perfect arc. The condenser is a pair of glass lenses forming a jacket for a water-bath, which cools the heat rays of the light so that a film may be slowed down or even arrested for 30 seconds without the least risk'bf firing the celluloid base. Ancnt this slowing down, one may remark that as there is no shutter there is no flicker, and the result is a " slow motion " effect that could be used with excruciatingly comic results in some comedy films. The water-condenser serves another very useful purpose. A plunging mirror instantly diverts the lightbeam in an upward direction, where it is picked up by a mirror and passed on through the lantern-slide carrier and lenses to the screen. Thus a slide can be instantly projected even without stopping the running of the film. It is obvious, therefore, that a special message, a miss ing title, or an explanatory note can be thrown on the screen instantly and in full synchronisation with the position of the film. Let us imagine that an essential sub-title is missing. The operator would prepare a slide and drop it into the slide carrier. On arriving at the part of the film at which the sub-title had to be inserted he would just drop the plunger mirror and stop the film travel. A reversal of this process would cause The new Projector ready for showing. the film to again proceed in its travel — and, so far as the audience is concerned, nobody would be aware that the sub-title was other than part of the film. There are other features of this new projector; such, for instance, as the automatic stopping and starting, the take up, the spool-boxes, which accommodate 3,000 feet of film at a run, the simple threading, and the economy in current, which I propose to deal with more fully in the next issue.