Black flag is an old idea. Here is a simple DIY twist on this idea for speedlights. The idea came from the New Jersey wedding photographer Neil van Neikerk
Simple, eh?
I tried this flag myself. It gives interesting light, but, as any other light source, it needs some getting used to. Here is a sample of a flash bounced of the celling with a foam thingy attached.
Example of light produced by the Foam Thingy
Black flag
The flash head was pointing up bouncing light off the celling. The flag was about 2 inch long fastened to the bottom of the flash head. The celling was low (about 9 feet) and the subject is very close (about four feet). As you can see that the majority of light on the face is ambient room light. There is some directional flash light coming from the top.
Here is another way how it could be done, but if the wall is not completely white, white balance would be very tricky
