I have noticed that Nikon does not have a ring flash that is i-TTL, am I over looking something? What are others out there doing for macro flash photography? I know sigma has one available. Any comments, suggestions?
You may want to post this question in the macro forum.
Flash for macro is a challenge. I like to use as much natural light as possible with maybe a little fill flash. I also like to use a reflector to get more even illumination and to reduce shadows. For shots that need a lot of flash I may use two flashes with some testing to figure out positioning. It's often not easy.
I've wondered about a ring flash as well, but I suspect that the very direct flash would yield harsh shadows.
I've been meaning to try the plastic bowl technique. The idea is to cut a round hole in the bottom of a white plastic tupperware/rubbermaid/etc. - this allows your lens to stick through or see through the bowl. Put foil along the inside on one side of the bowl and illuminate the other side with your flash. I'm sure you can find pictures on the web if you look around. I think I first read about this in a John Shaw book.
It basically works like an omnidirectional diffusor around your lens. Not sure how to get it attached to the lens though.
I asked a similar question a number of months ago in the macro forum. The answer was that the Sigma ring flash was usable but not the Nikon...
(I never tested this). I finally decided to use two wireless flashes on a special bracket and I am pretty happy with that setup.