Some Phases of the Optical System of the Projector
F. H. Richardson · Transactions of the Society of Motion Picture Engineers · 1919
For the past twelve years we have been engaged in the study of the practical optics as applied to the motion picture projector. Through observation, we discovered that the projection lens of our projector did not pick up the entire light beam, whereas others that had lenses of equal diameter did pick up the entire light beam.