. Motion picture electricity. perfect and practical direct current motion pictureprojection. The cut is intended to show the carbons inperfect alignment, when the lamp is tilted at an angle of30 to 450 back of the vertical position with a practicallyhorizontal machine table. The carbon setting in Fig. 65is thoroughly practical and as efficient as practical resultswill permit. With an arc drop of 50 to 55 volts, splendidresults are obtained, and by setting the lamp at the properangle an elliptical spot can be secured on the apertureplate, which is horizontally oblong, that is, wider than it 120
. Motion picture electricity. perfect and practical direct current motion pictureprojection. The cut is intended to show the carbons inperfect alignment, when the lamp is tilted at an angle of30 to 450 back of the vertical position with a practicallyhorizontal machine table. The carbon setting in Fig. 65is thoroughly practical and as efficient as practical resultswill permit. With an arc drop of 50 to 55 volts, splendidresults are obtained, and by setting the lamp at the properangle an elliptical spot can be secured on the apertureplate, which is horizontally oblong, that is, wider than it 120 MOTION PICTURE ELECTRICITY is high. This is an important point because the picture iswider than it is high, making it necessary to have, if pos-sible, a spot which is wider than high. One often hearsthe expression and I got a perfectly round light-spot.:This refers, of course, to the spot of light on the shutteror on a card held in front of the aperture. A round spotfor motion picture projection is not ideal. The spot which. Fig, 65 66 is wider than it is high is preferable and more efficient,and such a spot can be obtained by setting the carbons inpractically perfect alignment, as shown in Fig. 65, and canbe controlled by tilting the lamp, or backward and for-ward adjustment of the upper carbon. Over-prorninent Crater.—Fig. 66 illustrates whatmay be termed a common way of setting carbons for di-rect current motion picture projector lamps. In this case,the upper carbon is set quite a little back of the centerline of the lower carbon, and the purpose of this settingis to coax the arc forward so as to make a large and con-siderably slanting crater on the upper or positive carbon. MOTION PICTURE ELECTRICITY 121 In theory this method of setting may be correct, becausethe crater will be more nearly parallel to the condensinglens, but under this condition we are again confrontedwith the difficulty of magnetic and other forces actingupon the arc, causing it-to burn on the upper edg
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Keywords: ., bo, bookcentury1900, bookdecade1910, bookidmotionpictureele00hall
