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which methods are described of filming the buckle occurring during the time that the film is stationary in the gate.
It has been stated that 50% of light is lost at the gate of the projector, and that the screen distributes 80% of the light in directions in which there are no patrons ; what steps can be taken to reduce these losses ?
Mr. R. H. Cricks : The question emanated from me. These two points represent the most serious losses between the rectifier and the patron's eyes. If they can be obviated, either current can be saved, or the picture made brighter.
Mr. R. Pueman : The efficiency of the screen might be much improved upon by the adoption of the lenticular principle.
Mr. A. Kingsmiel : Does not the rear shutter involve greater loss than the front shutter ?
Mr. R. Pulman : To a slight extent this is so, but the loss is well justified by the reduction of gate heat.
Mr. S. T. Perry : I attribute the introduction of the rear shutter to the use of the 6in. condensers for the Hall and Connolly arc, and the 14in. mirror of the Magnarc.
Mr. R. H. Cricks : On the contrary, twenty-five years ago, a certain exhibitor was dissatisfied with the high gate heat produced by his 5 J in. mirror arcs ; he extended the shutter shafts of his Pathe projectors and fitted a second shutter — the predecessor of the modern twin shutter.
What precautions are taken in earthing sound systems in kinemas, and why ?
Mr. W. F. Garbing : Precautions are taken in earthing sound systems mainly for three reasons : namely, safety, prevention of extraneous noise from the speaker system, and to provide stability of the amplifier system.
When installing sound equipment, it is essential that screwed steel conduit be used to ensure good electrical continuity. The sound-heads, amplifier racks, and any other cabinets containing equipment should be connected to a common earth by means of separate conductors, which should have a current carrying capacity of not less than the largest size of cable used in the installation, usually 3/.036.
In what way does a deteriorated or resurfaced screen, impair sound reproduction and picture quality ?
Mr. F. H. Sheridan-Shaw : Every time a screen is re-surfaced, the perforations become more clogged, eventually leading to a loss, particularly in the high frequencies, of twenty per cent, each time. There will be no deterioration in picture brightness. Generally speaking, the deterioration of a screen depends upon the atmospheric conditions in the theatre, where the theatre is situated, whether it has a plenum plant, and whether it has tabs. Cleanliness behind the scieen cannot be over-emphasised.
In what manner can the presentation of lantern slides be improved ?
Mr. S. T. Perry : The lantern slide is woefully out of date. Most of them show a tendency to vibration ; the arc lamp should be H.I., to maintain the colour of light when changing over from film ; the lens should be of shorter focus to enable the slide to fill the screen, and most important of all, the slide carrier should accommodate the American oblong slides, and the condenser should be of 5in. diameter to cover them. Many slides are too dark. Bi-unial lanterns would be an advantage, permitting the change from one slide to another to be by iris diaphragm.