I am getting set up to shoot flash for fill with my 500mm. I will be using a 550ex flash for now. I made a flash bracket just fine but I need some information for the final dimensions. I am curious how far off the center axis of the lens the head of the flash needs to be to eliminate the red eye / steel eye situation. The commercial brackets do not seem to have much adjustment to them but it seems to me the farther the subject the higher the flash needs to be. I know the flash will only work to a certain distance but just curious if making my flash height adjustable is really needed or if a fixed height serves well enough. I will be using a Better Beamer if that makes any difference. Thanks for the help and thoughts.