Nissin Di-622 flash gun: Poor flash
I have the Nissin Di-622, the only problem is when the flash-head is at 90 degrees – that is to say when mounted on the camera (Nikon D90) the flash head is parallel with the lens, and set on TTL the flash is always poor and the picture badly underexposed, regardless of which lens, ISO, or shutter speed or distance from the subject.
I am very disappointed with it, and feel it's been a waste of money. I went back to the dealership from where I got it and all they said was thats how they are more or less. So it has laid in its box for the majority of the 15 months I've had it. The intention was to have it on TTL for quick shots and know they would be right.
Don't feel like forking out for a repair if that's needed. I think I'll just forget about it and put it down to bad luck, won't buy anything else Nissin.