Page:Popular Science Monthly Volume 92.djvu/242

 Mixing Colors on the Screen

A new way of obtaining motion pictures in natural colors By Max Fleischer

��Unexposed film

���EVERYBODY knows fhat motion pictures appear to be alive because the eye is not able to tell when one picture is flashed on the screen and anoth- er takes its place. The phenomenon is known as "retinal persistence." In the Kinemacolor process of reproducing scenes by motion picture photography in actu- al colors, retinal per- sistence is relied upon to secure the color effect as well as the effect of motion. In the Kine macolor process an exposure is made to rays that have passed through a blue filter, and then another exposure to rays that have passed through a red filter. Thus, blue and red exposures alternate throughout the entire picture. In order to obtain the effect of natural colors on the screen, it is obvious that the film must be projected at double the usual speed, simply because it has been made in the first place at double the usual speed. As the eye views the pro- jected picture it is bom- barded by red and blue images which succeed each other so rapidly that the colors are combined. A mixture of red and blue is the result. In other words, the screen receives two entirely separate colors in rapid succession and the eye is forced to mix them. Our eyes are fooled be- cause they are slower than the projector.

This explanation is nec- essary in order to under-

��Film receiving re-' filtered image

��'.flectors".

Ray-spirtting plane

Single lens

-Shutter Reflector' Film receiv-

��stand the basic principle of the new Technicolor process. Here two sets of photographs are also made, not at suc- ceeding intervals, but simultan.eously. These pictures are separated the dis- tance of two pictures on the film, to allow room for double lens- es used in projection. The registration of the colors is accurate, and the eye is not fatigued.

Double photog- raphy is made possi- ble by an ingenious light-splitting device which is located in back of the lens. The accompanying dia- gram explains the principle clearly. The light-splitting device is nothing more than a prism, the face of which has been coated with silver in numerous squares comprising exactly one-half of the total surface area. The balance of the surface remains transparent. One set of rays is

��Ing blue filt- ered image

CiaW advances filnn double lenqtn at each exposure.

Exposed film.

��The motion - picture camera which takes two pictures simultaneously at the usual rate of sixteen per second.

��Red filter

��lilter

��Ray to film

��Camera lenics

���Ray to dim

How it works.

��«y marks are ctedw;«h the tcenes and Bdjuitedon the screen

��Above: The rays of liRht coming through the lenses are spht into two parts by a novel form of reflector; part of the UkIU passes throUKh a red filler and part through a blue filter.

To the right: How the blue and red exposures appear on the strip of film for projection.

���First red A and blu« A photographed ani projected uUsneously

��Second red B arid blue B together

��Third redCsr>d blu« C together

��Fourth ted D and blue D to9eth«r

��220

�� �