The model Cristian brought was in great shape but had very little experience (a challenge to be addressed in another entry)
So despite what the data says lights did go off you will also notice the shutter speed was 1/800 .
Most of you know that your "normal sync speed" on a DSLR is 1/200 1/250.
Any faster you will start seeing that black band somewhere on the image. One solution is lights that use HSS (high speed sync) another is strobbing your flash at the right frequency, or shooting a Medium format like a Hasselblad. Because the shutters are actually little blades in the lens. (referred to as leaf shutter)
I am normally not a technical shooter but this was one of those moments where because I was getting these results on the Nikon I was going to have to geek it out a little.
so it was a questing of stopping the lights down .
If any of this was unclear? or you want more detail just leave a comment and I can do my best to address that, or cover it next time.
Until then... Keep shooting!