I came across a terrific video today. It's hosted by photographer, Jay Morgan, and I think it's one of the best and most succinct and easy-to-digest videos I've seen regarding softbox selection.
Most glamour photographers often go with the largest softboxes they have, leastwise for their key or main light. Often, that's a great choice. Traditional softbox wisdom says size does matter and going big with softboxes often yields pleasing glamour results. The bigger the light source, after all, the softer the light. And soft light is something we generally prefer when shooting gorgeous models for glamour pics.
Soft light, however, isn't always our first choice. Sometimes, we want to cast shadows to play dramatic roles in our images. The best way to let shadow do its thing is to reduce the size of the light source (relative to the model) so there's less wrap-around and the shadows become more obvious and defined.
Glamour photographers are also interested in coverage, that is, how much area will my modified light cover? One would think the bigger the softbox, the more area it covers. Sounds like a reasonable assumption, no?
As you watch the video, you'll discover that various sizes of softboxes behave in almost identical ways in some ways, and very differently in other ways.
Here's Morgan's video:
The pretty girl at the top is Chayse. I was shooting in a warehouse in downtown Los Angeles. I used a Photoflex 5' Octo for my main and a couple of kickers from behind, either side, both modified with small, shoot-thru umbrellas. As always, you can click the pic to enlarge it.