Response to IMAGE SPILLING OUT INTO FILM EDGE

The film actually act like an optical waveguide, just like the fibres used in medical endoskopes. When a light ray passing through the film hits the film/air interface, a little light bounces back into the film following the rule angle incident = angle reflected. Film manufacturers provide their films with anti-halation backings to keep the amount of light reflected back small, because the reflected light impairs the image sharpness. (You can study the effect with Kodaks IR film. This one has no such backing, and the effect is so strong - and the film so sensitive - that you must not even put it in your camera w/o a changing bag, because the film acts like a waveguide to an extent that several negatives may be fogged.)

[ Previous | Next ]