International projectionist (Jan 1943-Dec 1944)

may increase the tendency of film to show in-and-out of focus effects, we have never found a single case of embossing that by itself gave focusing difficulties. One fact was observed, however, that fresh film, and especially film not thoroughly dried, tended to emboss more than well seasoned and dried film. Since it is also a fact that insufficient drying and seasoning tends to produce in-andout of focus troubles from other causes, we sometimes find that film that has been embossed has also shown in-and-out of focus troubles. Flute or Long Edges. — The fourth type of film distortion, flute or long edges, is now seen more often with safety film than with nitrate film. A typical example of flute or long edge film is shown in Figure 2. It is caused by shrinking the center of the film without shrinking the edges or, conversely, by stretching the edges. (a) Flute from shrinkage of the center of the film: When film, especially safety film, is projected repeatedly at high heat intensities, the center tends to shrink more than the edges, causing a particular type of flute often known as "twist," since a strip of film stretched between two points gives the appearance of being twisted. (b) Flute from stretching the edges of the film by means of recessed rolls: The edges of the film are often stretched in processing machines by pulling the film too tightly over recessed rolls while the film is wet or while it is hot. (c) Flute from stretching the edges of the film by the use of twisted strands: Occasionally processing machines are designed in which the film is turned between each pair of rollers so that the emulsion side will never be in contact with the rollers. If the distance between the rollers is too short this twist puts FIGURE 2. Flute, or long edge in cine film. I ill I 1 I ill an additional strain upon the edges of the film which often produces flutes. (d) Flute from stretching the edges of the film through sivelling ' of the edges: Flute is sometimes produced in raw film if a tightly wound roll is exposed to very high humidities. Moisture is absorbed by the edges of the film but does not travel far into the center. This means that the edges increase in thickness and each layer builds up on the one under it. Even though this thickening of a single layer of film may amount to only 0.00001 inch, there are, nevertheless, 650 layers in a 1.000-foot roll of film. The increased thickness of each layer builds up on those below it so that the edges of the roll will have a diameter 0.0065 inch greater than the center and this increased diameter can occur only by stretching the edges of the film. Buckle or Short Edges. — The kind of distortion that has caused by far the greatest amount of trouble with 35mm film is short edges. At the Eastman Company the term "buckle" is reserved entirely for this type of distortion, although in the trade almost any type of distortion is frequently referred to as "buckle." Figure 3 shows a typical example of , " FIGURE 3. Buckle, or short edge in cine film film. buckle produced by short edges. It is ordinarily produced whenever a film containing a sufficient amount of water or residual solvent is wound tightly and permitted to dry so rapidly that the moisture can not diffuse from the center toward the edges as rapidly as it is taken away from the edges. The edges shrink as_ they dry and may become permanently distorted. The effect is worse with film having a high potential shrinkage than with modern low shrink film, but even this film can be buckled due to moisture losses if conditions are right. (Continued on page 20) LIBRASCOPE, INC., AWARDED ARMY-NAVY "E" Librascope, Inc., Burbank, CaL, is another manufacturing subsidiary of the General Precision Equipment Corporation (formerly the General Theatres E q ui p ment Corporation), that has received the Army Navy "E" award for excellence in production of war material for the Navy. The announcement was made by Earle G. Hines, president of the General orHerbert Griffin ganization. Librascope, Inc., is managed by Herbert Griffin as president, who also is vice president of the International Projector Corporation, and is well known in the motion picture field. The concern produces a computer of unique design for use by the ordnance and aeronautical departments of the armed forces. It is the second subsidiary of General Precision Equipment Corporation to be awarded the "E" flag, the other being the Cine Simplex Corporation. Syracuse, N. Y., which in peacetime was engaged in the production of cameras for use in motion picture studios and for newsreel work. General Precision Equipment Corporation's six manufacturing plants at the present time are operating at capacity both in the manufacture of their regular motion picture equipment, most of which is for the government, and also in the manufacture of instruments of critical and urgently needed types. AUGUST 1943 13