When you have tried to twist and turn your main light in every possible angle shooting studio portrait to create something new, you can always put something between the model and the light. That will instantly give you a million new combinations.
This is a portrait of a Swedish guy wanting a couple of headshots for his portfolio and profiles. No retouch, just creative lighting. And this is from the last setup after we had finished the more ordinary ones.
Flagged main light setup diagram
As I said, we had already gone through the usual setups when I wanted to reduce the amount of light hitting his face, to define the shape in a new way. Just a grid on the beauty dish (a white Profoto Softlight Reflector with a Profoto D1 250 Air) was not really enough as is still sends out a large beam of light.
Flags and strange light
What I did was to clamp a large piece of black foam core on a stand, somewhere between the beauty dish and his head.
It blocked about half the size of the gridded reflector which created a light that looked a lot different than with just the grid.
The strange this is when trying to block light, it is interesting to see how light can reach places you would have thought were blocked with your flag. Just the smallest adjustment of the flag will get you a whole new light. Very fun, but also very frustrating sometimes.
In the catchlight, you can see that more or less exactly half of the beauty dish is visible as a reflection. The small light beam makes it very unforgiving to skin imperfections, so using this light without no retouch after or professional make-up before might not be optimal. With a skin that can handle harder light (i.e. drier or with make-up) would have produced a more polished result from the start.
Next time I try this kind of studio lighting, I think I will use a harder light. That might be easier to control as the light is more straight, but there will still be a lot of work to place the flag right to get the result I want to achieve.
To make it even more interesting, instead of just flagging the light, some kind of pattern from a gobo can modify the light even more. The possibilities are endless.
For this portrait, I used a Nikon D700 and a 85mm/1.4 lens. Smaller adjustment were made in Lightroom 4 to enhance the effect of the very local lighting and sharpening was made in Photoshop, but no real retouch.
I would highly recommend you to place something between your light and your model, it is a fantastic way of throwing in an element of chance in your lighting. In a good, but sometimes frustrating way.