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.

ture. To illustrate this the authors' took a motion picture lamp, focused it in a moving picture machine and measured the screen illumination. The lamp was then moved to one side in steps of i-io" at a time. The following results were obtained: Filament Centered lO lo' lo' off center Relative light on Screen (Lumens) loo 88.5 77.0 66.0 38.0 28.0 Similar results maintain if the filament is too high or too low. Proper centering of the light source is therefore essential to efficient projection. Very material losses also occur if the light source is placed too far ahead or too far behind its proper location with respect to the condenser. A test showed these losses to be as follows: Relative Light on Screen (Lumens) 100 (c a a i( ic 00 72.5 63 54 44 Filament in Focus on Shutter " I 10" ahead of proper location " 2/10" " " " " 3/10" " " " 4/10" " " " " 5/10" " " " No spherical mirror was used in this test. If the lamp filament is moved back of this position, an increase in screen illumination is obtained up to the point where the filament images are focused sharply on the aperture plate. Here, however, the unevenness of the screen is so great as to be objectionable. Probably a compromise between maximum evenness and maximum illumination is acceptable. Such a compromise will result if the filament is moved back about }i'' from the point where it focuses most sharply on the shutter. The following method may be used to locate the lamp filament: Light the lamp and set it approximately in its operating position. That is 2" in back of the edge of the 3>^" diameter prismatic condenser or 2^" in back of the edge of the 4}^" prismatic condenser. Place the lamp so that the plane or broad face of the filament is parallel to the front face of the condenser.* Center the lamp with respect to both sides and up and down by adjustments provided on the machine for that purpose. When the filament is properly located in the horizontal «(C K Fig. 5 * Scale drawings of this set-up are furnished by the manufacturers with instruction sheets accompanying motion picture equipment. 52