You'll have to forgive me if someone has shared an experiment like this before on the Forum, but it was a lot of fun for me and I'm happy to share it with you all. I've been fascinated by the discernible Start/Stop motion of the sweep second hand on my Cal. 8500 Aqua Terra ever since I put the watch on for the first time. During moments of quiet contemplation, while staring contentedly at my watch, I've tried counting how many Starts/Stops the second hand makes between each minute marker on the dial. But it happens so quickly -- certainly quicker than my aged eyes [and brain] can discriminate, and I have to give up on getting a reliable count. Then I had a "brilliant" idea: use the high speed video mode on my cell phone to record the second hand's motion, then try counting the individual Start/Stops when the video is played back in Slo-Mo. It was like magic -- the individual Start/Stop movements were so easy to see! Seven starts and stops between each minute marker, every time. But this should not be a surprising result. I've read somewhere out there on the Internets that the 8500's nominal beat rate is 25,200 beats per hour. If you do a little arithmetic, that comes out to exactly 7 beats per second. I'm seeing the actual beat rate on my watch face! Eureka!
You can accomplish the same thing with a long exposure. I took this one a few years ago of my Blancpain Leman: Watch is gone now...miss it sometimes... Large date was okay, but the 100 hour power reserve was very handy. For a long time it was my most accurate watch. Cheers, Al
@Archer -- I love that approach. It's Ultra-Visual! Ah...Blancpain. The Fifty Fathoms is yet another dream watch of mine. Sigh...
I do have a follow-up question for those who are knowledgeable about such things: Is a single "beat" one change in the direction of rotation of the balance wheel?