Exposure in film photography

So here's what I mean: although motion picture film advances at a rate of 24 fps, each frame can't remain stationary in the gate for the full 1/24th of a second, as the mechanism must allow time between each exposure for advancement to the next frame; hence, a normal 180° angle of the rotary shutter results in an exposure of 1/48th of a second, with the film then advancing to the next frame (while the shutter is in the "closed" position) during the remaining 1/48th of a second.

Now, am I off-base on that, or is "2 frame pull down" merely a term economically-coined to describe that operation (rather than a literal one indicating that the sprockets actually advance the film 2 frames at a time)?


Yes, Doghouse, that is exactly right. No literal advancing of two frames at a time, but one pulled down, held, then moved on. Good for you for knowing that. Oh, what an interesting conversation all of us have had on this thread, thanks to Flynn! It's been great.