Photographer Glyn Dewis shared this cool little technique that lets you work with a black background even if you don’t have an actual backdrop with you. It’s a fairly common trick that he refers to as “the invisible black background,” and it’s a nifty little tip that many photographers may want to keep up their sleeve.
The technique is pretty simple: all you need is your camera, an off camera flash, and an umbrella. In Dewis’ case, he’s using a Nikon D800, a Canon Speedlight (he dropped and broke his Nikon flash) and a Pocket Wizard so the two can communicate.
Taking into account a max flash sync speed (not hypersync) of 1/250 sec, Dewis sets his exposure there. He then drops his ISO to the lowest possible setting and stops down his aperture until the resulting test shot (without flash) comes out completely black.
Then he turns on the speedlight, closing down the umbrella so that it funnels the light only at his subject, and takes the same shot, now with flash. The background will still be as black as it was in the no flash test shot (assuming there’s no unchecked reflections), but his subject is lit. Voila: instant black background.
Obviously, you’ll have to play around with this until you get the light just right, and when you’re indoors you’ll have to deal with more reflection issues, but it’s a neat tip that’ll provide a dramatic-looking black background on the fly no matter where you are.
(via ISO 1200)