We use Optical Character Recognition (OCR) during our scanning and processing workflow to make the content of each page searchable. You can view the automatically generated text below as well as copy and paste individual pieces of text to quote in your own work.
Text recognition is never 100% accurate. Many parts of the scanned page may not be reflected in the OCR text output, including: images, page layout, certain fonts or handwriting.
296 HANDBOOK OF PROJECTION FOR
not possibly be what it should and must be for best results, hence the result will inevitably suffer at least to some extent, insofar as concerns sharpness of focus. Of course as the distance increases the view of the screen from the projection room will become less distinct.
But this element interlocks with another to the extent that any distance sufficiently short to require a projection lens of very short focal length — say less than 4 inch E-F, is highly objectionable, because very short focal length lenses do not give sharpness of definition all over the field.
The whole subject of projection room location is full of complications, but it may be set down as fact that, except in those few cases where extraordinary sacrifice would have to be made to do it, it will be a paying proposition to so locate the projection room that the picture height will not be increased by more than 5 per cent, through distortion due to angle of projection, and the projection distance (throw) such that not less than a 4-inch E-F projection lens will be required and as little more than seventy-five feet from lens to screen as can be accomplished.
FRONT OF BALCONY LOCATION.— The location which promises best results in large theatres is in the body of the balcony. This location is a recognized possibility by some architects now, and will, we have faith to believe, become increasingly popular when theatres are planned in which there is to be a balcony, and in which other available locations would either give a too steep projection pitch, or else a too great distance of projection.
In Fig. 81 we see the diagrammatic representation of the possibility of such a location. The possible objections are: (a) Cost of installation. (b) That the balcony will sag somewhat under stress of load, (c) That proper ventilation will be difficult, (d) That in case of fire there would be danger of panic by reason of smoke coming out in the midst of the audience.
These objections are, except for the first named, capable of being reduced to practically nothing at all. The balcony will settle somewhat, yes, but it is a simple matter to construct a compensating projector table which will take care of this and keep the picture automatically centered on the screen. See Fig. 81 A. Such a room may be ventilated as much as may be desired. It is merely a matter of cost of necessary vent ducts, and their installation ; also ducts may be easily provided which will carry away every particle of