Butterfly lighting also known as Paramount or Dietrich lighting after Marlena Dietrich, who refused to have her picture taken with any other set up. It takes the name butterfly from the small shadow that is cast by the nose from the main light which is set at about 45 degrees above the subject.
The setup requires a main light mounted on a boom which should be above the model at about 45 degrees to their face. This is all that is mandatory for this setup but it is also convention to add two rear lights to define the shape of the model, and this makes a much more pleasing image.
The camera is set directly in front of the model and shoots under the main light. in most cases the main light is fitted with a beauty dish to give a smooth light that flattens the imperfections in the skin, a soft box can also be used, if shooting a young person with good skin the beauty dish can be used on its own or with a honeycomb to straighten the light, for older people and people with less perfect skin it is a good idea to cover the dish with a difuser or to use a soft box instead. A beauty dish with a difuser acts very much like a soft box.
This is the basic set up:
In this diagram the key light is the Beauty dish set above the model, the two back lights are not essential but they create a rim light around the model that removes her from the background. One of the nice features of Set A Light is the ability to move around the 3D studio and produce a picture to remind you when you get to the real studio. One thing to mention about Set A Light is that there are no booms in the equipment list, the way they suggest adding a boom is to turn off the stand so that the light looks like it is hovering and place it where the end of the boom would be. This makes sense when building a set up in Set A Light as it stops all the stands getting in the way:
I have been very lucky to be given the position of photographer in residence at the Chapel in Ash Vale which is giving me a lot of opportunity to test and lean all I can about studio photography. All that was left was to go to the studio and try this out, Here is a quick iPhone grab of the set up:
And the result: