Subscriber and Workshop Member
Sigh. I made high-speed (slow motion) videos to go with that waveform. And I WILL spare you those. Slowed down 50 times, it sounds like the hold of the Nostromo, full of spooky echoes. Noises A and B remain unidentified. But the leaf snaps shut at C. Then the aperture blades simply crawl. That entire 1/10 second from C to D is the aperture closing down to f/11. I can't tell exactly when the focal plane shutter opens, because there is a closed leaf shutter in the way! The leaf snaps open at E - it's faster than my frame rate, which it better be if you're able to shoot 1/800 second with it. At F, the end of the exposure, the leaf snaps closed. What's amazing is that the leaf snaps open again at H, making that last big noise. So at F or H, or possibly G, the focal plane shutter must have closed. After that, the aperture blades crawl open for the rest of that time slice, and the mirror comes down.
I suspect I've gone OT here. If I do more shutter analysis, it will be in a different thread.