Transactions of the Society of Motion Picture Engineers (1916)

Record Details:

Something wrong or inaccurate about this page? Let us Know!

Thanks for helping us continually improve the quality of the Lantern search engine for all of our users! We have millions of scanned pages, so user reports are incredibly helpful for us to identify places where we can improve and update the metadata.

Please describe the issue below, and click "Submit" to send your comments to our team! If you'd prefer, you can also send us an email to mhdl@commarts.wisc.edu with your comments.




We use Optical Character Recognition (OCR) during our scanning and processing workflow to make the content of each page searchable. You can view the automatically generated text below as well as copy and paste individual pieces of text to quote in your own work.

Text recognition is never 100% accurate. Many parts of the scanned page may not be reflected in the OCR text output, including: images, page layout, certain fonts or handwriting.

from time to time due to atmospheric changes and moisture treatment it is not practicable to undertake to guide the film by having the teeth on both sides of the sprocket wheel the same length as the perforations in the film. Therefore, it seems necessary to make the teeth on one side of the sprocket wheel to fijt closely the length of the film perforation and then shorten the tooth on the opposite side sufficiently to allow ample freedom for expansion and contraction in the width of the film. At a recent meeting of the Society, the consideration that preceded the adoption of a standard for film perforation presented some complications because of the expected future relationship between the film perforation and the form and size of the sprocket tooth, and of finding a practical means for producing the film sprockets. It was the belief of some of those present that the use of a film perforation with circular ends would present complications in the forming of the sproc FlG. 1 Side and end view of sprocket tooth. ket teeth to fit the perforations that might be so great the plan would not be practical, and that teeth made to fit a rectangular perforation with rounded corners would eliminate the complications in manufacturing, make it possible to grind both the ends and the sides of the sprocket teeth, thus correcting both the alignment and the spacing of the teeth, and would make it possible to secure the greatest degree of accuracy in the projection of the picture on the screen. Mr. Bell of the Bell & Howell Company of Chicago, stated that for several years past they have been using on their film printers, sprocket wheels with teeth on one end made to fit the perforations in the film to prevent side movement, while the teeth on the other end of the sprocket wheel are made shorter. This plan has been possible with them because usually the film manufacturer who uses their goods adopts their equipment complete including film perforators, cameras.