British Kinematography (1948)

that. We should be very pleased to see theatres which had balconies coming out to, say, 50 feet from the screen. That would be the ideal position for the projector, hut lew existing theatres satisfy that condition. Mosl of them are 70 or perhaps 90 feel hack. My. Schlanger : In contemplation of building a new theatre, might that be the course to follow ? Mr. WEST : Yes, sir. Obviously it would be preferable to have the projector back in the box which is the right place for it, but in determining the best position for the projector in the auditorium we are subservient to the economic cost. I believe (hat we could produce a large projector with a 40-inch mirror which could be put in the projection box, and would provide sufficient brightness, but it would be very expensive. The glasswork alone might cost about $16,000 and furthermore the production output would be very slow. I believe it is the same over here. It might take two years to produce one only. It, therefore, appears to be neither an economic nor a practical proposition. We. therefore, have to compromise with a, smaller mirror, smaller dimensions of projector, and a smaller throw distance to secure the brightness for a given size screen. If theatres are to be designed for the purpose of large-screen television, then the balcony should be designed so that the projector can be mounted on the front of it at a distance not more than 50 feet from the screen. Mr. Paul J. Larsen : 1 agree that the front of the balcony is a very nice position for the projector, but there is, in my opinion, a very much better place where the projector can be placed in theatres without disturbing the seating arrangements or anything else, and that is by hanging it from the ceiling. It can be supported there very rigidly and solidly, and projecting downward to the screen. In that way you could have your control box located in the projection room or in the balcony, and that would not be taking up any space in the orchestra stalls. Mr. West : That is an interesting point of view. I think that we are rather afraid that our roofs are not strong enough to support the equipment. There is the question of servicing the projector also. Mr. Larsen : It could hang from the ceiling most of the time just like a chandelier, and it could be lowered to the floor by pulley rope when servicing is required. Mr. West : Would not roof vibration cause trouble ? Mr. Larsen : I do not believe that it would be serious. I do recall some tests made some time ago in projecting still pictures that way. Naturally you would not depend on a single rope but you may use a triangular rope arrangement which would hold it quite steady. .\ii. Schlanger : Would not that be in the line of the film projection in the projection room ? Mr. Larsen : You would place it at an angle so that it would not be. Mr. Schlanger : That might require quite a steep angle from the television projector to the screen in order to get above the regular beam of the motion picture projector. Mr. Larsen : It would not be any worse than trying to have it down in the orchestra and trying to project it up on to the screen. Mr. Schlanger : That position in front of the balcony that I saw in Mr. West's diagram was practically a straight throw. REFERENCES The original paper embraced material included in earlier papers, as follows : 1. /. Brit. Kine. Sue., Vol. 2, No. 1, 1939, p. 18. 2. J. Brit. Kine. Soc, Vol. 2, No. 2, 1939, p. 11 1. 3. /. Brit. Kine. Soc, Vol. 2, No. 2, 1939, p. 113. 4. Proc. tt.K.S. Theatre Div., 1945/6, p. 22. 5. /. Brit. Kine: Soc., Vol. 9, No. 1, 1946, p. 13. ADDENDUM A paper was delivered by Mr. A. 0. I). West at a meeting of the International Television Conference, held at Zurich on September 9th, 1948, which contained similar material to Parts III. IV. and V of the above paper. Mr. West was however able to report an increased light output of the projector (see 189) which enabled a screen measuring 16 ft. X 12 ft. to be illuminated to a highlight brightness of 8 foot-lamberts, with a contrast ratio of 50 : 1. At 30 degrees off the centre line t he highlight bright ness was 5 foot-lamberts. The total output of light (calculated both from brightness measurements and from data concerning the luminous efficiency of the equipment) was estimated at 800 to 1,000 lumens. The gamma was almost constant throughout the range. The colour approached closely to a true black-and-white picture.