As any regular reader knows, I purchased a movie camera last year, which allows me to film movies in slow motion, covering actions with frequencies out to perhaps several hundred hertz — normally film at 420 fps, but can go to 1000 fps. This year, I went in the other direction. I bought an attachment for my DSLR that allows me to take time-lapse sequences, which I can then stitch together.

Here’s an example from last night. The weather forecast was for late-afternoon thunderstorms, but unfortunately for this demonstration they passed to the west of me on their way into Pennsylvania. We did get some rain just after dark, and this is the development of that storm system, shot at 30-second intervals over the course of about three hours.

The attachment is called an intervalometer, which a pedant (who, me?) will note is incorrect. It’s not a meter of any sort — it’s not measuring anything. It merely sends a trigger signal to the camera at a programmable interval.