Standards and Requirements of Projection for Visual Education<!--<xref ref-type="fn" rid="fn110.5594_J05471">*</xref>-->

Abstract

In the development of visual education the choice of material, planning of sequences, photography, laboratory work, and editing of the finished product receive the most careful attention, but the projection of the finished product is very much neglected. — The inevitable result is eye-strain, either severe or slight. the straining of eyes already taxed by constant study may easily lead to serious results. a slight strain may either induce drowsiness or otherwise retard the mental processes so that much of, if not all, the advantage of the visual method of presentation may be nullified. — The conditions for projection free from eye-strain are the same for educational as for theatrical projection, but conditions and limitations peculiar to the classroom, such as the shape and size of the rooms, lighting arrangements, lack of beam-power of the projectors necessitating the use of specular or semispecular screens, and the short projection and viewing distances frequently encountered assign a major importance to factors that are negligible in theatrical projection. — Particularly is this true of the projection of opaque objects where all these factors are evident simultaneously and all in large degree. two experimental opaque object projectors are described, one of moderately high power and the other of extremely high power. two opaque and five translucent screens are analyzed.