Ring flashes are great tools. They give you virtually shadowless illumination of your subject and hence provide a very particular look. Many fashion and portrait photographers use them, either as their main light, but often also for fill-in.
Over the last few months I have been trying a “budget” way to obtaining a ring flash that would normally cost you more than 1000 USD.
This budget solution is a ring flash adapter from Orbis.
The flash is an accessory to your normal TTL-flash and effectively modifies the emitted light. In conjunction with an Orbis arm,
and a flash cord I eventually pieced together the following portrait rig for my Sony A900 and the 70-200:
works really well. and it is compatible with flashes of any brand and make.
see also this video review:
and here are some links to other sites and articles:
and some sample photos: