"There's always one moment when the light's at its best, so I would get to my location and have it all scouted and know what I was doing," he says. "Then, when the light started getting good, I'd begin working on my sequences, using manual mode and keeping the exposure the same across the frame. I would do quite a few sequences as the light evolved, to make sure I had captured it when the light was at its best."
As well as choosing the best time to shoot, David had to tackle the variation in light across the whole of the frame. "Getting the exposure right is really difficult and you have to meter from the middle of the scene," David says. "But it does help if you've got a camera such as the EOS R that offers good shadow and highlight retention. Then, in post-production, you can bring out detail in the darkest shadows or brightest highlights in the frame."
Variation in light was less of a problem on the night shoot, but photographing in those conditions was even more time-consuming. "The trouble with the night shoot was that the actual exposures were something like 30 seconds each," he says. "So if you're doing 21 frames at 30 seconds each, taking into account the time you're spending re-composing, it takes around 20 minutes for each sequence."