15 perfs is the loop size. The camera needs a very specific loop size to ensure the film runs smoothly and silently through the movement, where the pull down claw is. too small a loop will create too much tension in the movement, and too large will create slack. 15 perfs ensures there is enough slack above the movement for the claw to pull down.
why we need to leave 15 perforation holes outside the magazine when doing the Takeup side?
15 perfs is the loop size.
The camera needs a very specific loop size to ensure the film runs smoothly and silently through the movement, where the pull down claw is.
too small a loop will create too much tension in the movement, and too large will create slack.
15 perfs ensures there is enough slack above the movement for the claw to pull down.