Journal of the Society of Motion Picture and Television Engineers (1950-1954)

Fold Tests,* was negligible for all the films except the Super XX Panchromatic Negative. Overdrying this film increased the brittleness. However, when the film was properly dried, it was not brittle. An examination of the various films for distortion showed that nearly all of them were fluted. This fluting seemed to be more severe on the films which had been dried at temperatures above 180 F. Poor alignment in the experimental machine may have been responsible for the distortion. It also may have been caused by the softening of the hard rubber spools at these temperatures with the result that the films tended to climb the flanges rather than to be guided by them. It is possible that the distortion could be eliminated in a well-built machine. However, our experience illustrates how easily the film can be distorted at these temperatures, and, therefore, the necessity of extremely good film transport mechanism in machines of this type. Attempts to evaluate the tendency for the rapidly dried film to go "in-and-out of focus"6 have not been very successful to date. It can be said that none of the rapidly dried films equalled the performance of the best of the normally dried films with which they were compared. On the other hand, little difference could be found between the average performance of all of the rapidly dried * The Vise Brittleness Test consists of breaking a loop of film, emulsion side out, between the jaws of a vise closed at uniform speed. The distance between the jaws at the instant of film failure is the value given as vise brittleness. This is usually done in a room held at 70 F and 10% R.H. after the film has been equilibrated to these conditions. The Pfund Fold Test consists of the folding of a short free loop of film alternately emulsion in and out. A fold is considered as a complete cycle. This test is also run at 70 F and 10% R.H., with the film equilibrated to those conditions. films when compared with the average performance of all of the normally dried films used in the test. The "in-and-out of focus" test used is rather severe and does not simulate trade^ conditions. It consisted of the continuous projection of a 45-ft loop of film by an arc projector operated at a light intensity approximately equal to the maximum in present theaters. The arc was a condenser type, burning a 13.6-mm positive at 170 amp, and equipped with an //2.0 quartz condenser set to deliver a mean net radiant flux to the film of about 0.5 watts/sq m. The image is projected with an //2.0 projection lens, and an observer sets the focus each time the start of the loop passes through the projector and records the focus position as indicated by a dial indicator. He also records the appearance of the image. The test continues until the image is steady and the focus becomes constant or until the loop has made 25 cycles. Under these conditions film will almost always go "in-and-out of focus," but the more cycles a loop of film will travel before this occurs the less the chance that it would give trouble in actual theater use. High-intensity projection of a 1000-ft roll of rapidly dried film in a trade use test did not cause "in-and-out of focus." This roll was projected four times per day for forty projections at the end of which time the focus position had become constant. Further work is being done on this problem but at present it must be concluded that the "in-and-out of focus" tendency of rapidly dried film may be somewhat greater than with normally dried film. If commercial installations of this type of drier are made, the product should be carefully checked for this defect and procedures established which will minimize the tendency. Projection life of the Fine Grain Release Positive Film rapidly dried was the same as for conventionally dried product as were also the tear values. 100 February 1953 Journal of the SMPTE Vol.60