I have two TTL converters for the Nauticam D850 and they are horrible. 90 percent are way under exposed. I am shooting all manual now on my macro work. They are essentially costly, useless electronics. In the most basic, close up, nudibranch simple shots one can do, the TTL fails miserably, significantly under exposes. Someone has to call out Nauticam for this. In my opinion they are selling an inferior product. When you compare the converter to my old system, a Nauticam D7100 system with fiber optic, nearly 90 percent accurate exposure. Granted the D7100 is using the cameras TTL system, but you would think that the engineers at Nauticam, who I consider very good at what they do, would have done more field testing before launching the board. Where I bought my housing, they could not get the first circuit board to function with TTL. They had to order another one, which worked topside. But until you actually put this in the field, underwater, will you recognize its inferiority for such a high end system.
Really disappointed.
Here is one image where TTL would not properly light the subject. Simple, easy. Ended up using manual. Strobes pointed close within 8-12 inches and directly at the subject. Could not have had easier situations for the TTL to function properly.
Will post some additional examples in a bit after my dive of images that the ttl would not work...well not in any case has the ttl actually worked.
Joe