Nikon F2 in slow motion
Check out this really cool video that shows a Nikon F2 film camera taking a picture at 1/2000 second at F16. The film is at 5,000 frames per second. The horizonatlly-traveling curtain is just a slit at this speed. The fastest speed the F2 can completely open up for exposure is 1/80 second, which is the flash sync speed. Notice how much beating the mirror takes with each exposure.