Accurately pulling focus is hard enough at 24fps—imagine having to do it for a high-speed video shoot without the aid of expensive gear. Well, cinematographer Matthew Rosen did it for a detergent commercial shot with the Phantom Miro. In this video, he shows you how he pulled it off using nothing more than a length of tape, precise timing, and his cat-like reflexes.
This particular shot was particularly challenging because the ad's director wanted a very shallow depth of field, meaning the margin of error was virtually non-existent. So, Rosen had to carefully find his plane of focus by using a paintbrush as a stand-in for the grains of detergent, then using a piece of masking tape to mark the closest and furthest focus points.
After that, it was a matter of timing his focus pull with the cascading detergent—a shot that only lasted half a second, mandating a focus pull of a quarter of a second.
With some practice and a little luck, this no-budget, high-speed focus pulling technique could really help you capture some amazing, super slow motion shots.