There's a real trick to getting ring flash correct. We had a little play-day here with the two Elinchrom units (the cheap one and the expensive one) and also with the bolt on extra bits... I want to say they were from Hensel but I don't rememver.
As you might expect, the cheap one (much smaller ring) and I believe the same unit pretty much as the Lencarta unit, is OK. The expensive one (much bigger) is quite nice. The bolt on reflector is gorgeous and the extra grid for that reflector is stunning.
You gets what you pays for!
But in the experiments, we found there was a real optimum position for the photographer, versus the model versus the background. From memory keeping the model around a metre or so from the Colorama backgrounds produced the best "readybrek" halo effect around the model. Also keep an eye on your position to the model, if you're shooting low and upwards, the shadow will be above the model. You need to keep it around chin height to get that glow effect.
But I have to stress, I am no expert on ring flash, I have literally spent a few hours playing with a few different units.
Saying that, I think I may have just picked up a
second hand Lencarta unit from one of my customers, so I will be finding out a lot more about it soon.