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. (We knew that when we named the journal, but have you ever tried to name a film journal?) If this is unclear, try me privately for an explanation when it is not 1 a.m. liz weis cuny ---- To signoff SCREEN-L, e-mail [log in to unmask] and put SIGNOFF SCREEN-L in the message. Problems? Contact [log in to unmask]