Slowing Down the Film

To the Editors:

I would like to thank Professor Vernon Shetley for pointing out that in my article “ANew Vision of Vision” [NYR, September 21] I incorrectly stated that films projected at less than twenty-four frames per second are seen as a succession of static images. The lower limit is indeed, as he notes, about ten frames per second. My purpose, however, was to give an example of how the brain creates the illusion of motion from a sequence of static images, and this is true of motion pictures if the projection speed is approximately ten frames per second or more. Of course, at lower speeds we see a sequence of still images.

Israel Rosenfield
New York City