I've heard of Clamshell Lighting. What is it, and when should it be used?
Clamshell lighting is a common way to photograph a head shot, often used in the fashion world. The general idea is you take 2 light sources, or a light source and a reflector. Both of them are roughly on-axis with the center of the person's face. You put one of them above pointed down, and the other lower pointed up. The end effect is that there are reduced shadows from any imperfections in a person's face. See this site for an example setup picture.
The reference I originally heard comes from PhotoFocus as a method of reducing wrinkles, scars, etc in a person's face.
Well, I'm afraid I don't have a snazzy diagram or picture for Clamshell Lighting... Because Clamshell Lighting = Butterfly Lighting, and thus the diagram is over on my Butterfly Lighting question/answer. :-)
Now I will say this, there are some who argue passionately that Clamshell Lighting and Butterfly Lighting are different because (so the argument goes) "Clamshell Lighting MUST use two lights! One above the head pointing down at 45 degrees and the other below the head pointing up at 45 degrees. Clearly this is COMPLETELY different from Butterfly Lighting which uses a light above the head pointing down at 45 degrees and a reflector down below pointing up at 45 degrees."
Personally that's too much stuff for my little head to contend with, so for me (and for a great many) photographers, since the setup is exactly the same for Clamshell and Butterfly lighting, and the outcome is the same as well... Clamshell Lighting = Butterfly Lighting.
In fact, I'll go one step further to alleviate (hopefully) all the synonyms... Clamshell Lighting = Butterfly Lighting = Paramount Lighting = Beauty Lighting = Glamor Lighting
I've updated the Butterfly Lighting article to reflect all the synonyms.
It’s called clam shell simply because you rig two softboxes as a giant gaping clam shell.
A common setup is to build your clam shell with a larger upper softbox and then a lower smaller stripbox. The upper softbox is about one stop higher than the stripbox. Using two softboxes gives you good control of the light.
Here is a link to the full article on clam shell lighting.