>Meryem--wheels appear to spin backwards when photographed if they >are spinning at less than 24 times a second (or a multiple of that). >They would have to spin at exactly 24 times a second to appear to >be stationary and faster to appear to go forward. As for "persistence >of vision," it is rather embarrassing to admit as a co-editor of a >journal of that name, that that theory ofperception has been disproved as >an adequate explanation of why we see film as moving, as has the psi >phenomenon. When we watch TV Persistence of vision comes in to play, but also the phosphor on the picture tube has a persistence as that little beam sweeps back and forth turning on and off at various spots of the screen. That's why I would rather have light letters on a dark background, cheaper electricity over the years and holds those little accelerated electrons that fly out of the tubes into my upper organs to a minimun. Your CRT should last longer too. 73, Uncle Art NE Pa. ---- To signoff SCREEN-L, e-mail [log in to unmask] and put SIGNOFF SCREEN-L in the message. Problems? Contact [log in to unmask]