I am currently photographing my watch collection, well actually trying to learn how to take better photographs of my watches or watches in general. One of the things I tried today was to see if I could capture the heart beat of the watch, i.e. bph (beats per hour).
Most watches today beats at one of the following bph (A/h):
18,000 A/h (2.5Hz)
21,600 A/h (3 Hz)
28,800 A/h (4 Hz)
and some, like the Zenith;
36,000 A/h (5 Hz)
So basically, if we were to break it down to beats per second (bps),
18,000 A/h = 5 bps (tick tock tick tock tick)
21,600 A/h = 6 bps (tick tock tick tock tick tock)
28,800 A/h = 8 bps and so on.
I was wondering if I could capture this with my camera. Set the camera to shutter priority and set it to 1 second. Mount it on a tripod and set the self-timer (to reduce vibrations).
The following is the results:
ETA 2801 - 28,800 A/h, so 8 bps. In the photograph below, you can see the sweep second hand moves 8 times in the 1 second block (as indicated by the two markers).
ETA 2750 - 21,600 A/h, so 6 half tick (a half tick is the first tick, the tock is the second half tick in a normal tick tock). You can see the sweep second move 6 times between the markers.
ETA2824 - 28,800A/h. Again 8 bps. The photograph below shows that the sweep second hand moves 8 times.
How cool is that. Now what can you use this information for? Well I can only think of the case where you want to buy the IWC Big Pilot 5002 and want to check if the watch is the 5002 with the 18,000 bph movement or the transitional pieces with the 5002 case and dial but with the newer 5004 movement that beats at 21,600. Of course the easier way is to bring it to a watchmaker and have it checked on a timing machine.
And there you have it, another piece of useful (or useless) information. :)