Male
Sebastian,
using a adapter ring will move the front glass a bit (1-2 centimeters) more far as without.
This is generally spoken not a problem, BUT it may create issues with vignetting with 180° fisheye lenses,
especially the SIGMA 15mm DG FE due it extreme short lenght....
Ok, seems to be that I have to ask them to make one of their housings for the Nikon D800 with a Subal port mount - just for me. I guess they won't do that or it will be very expensive - making the Subal housing for the D800 attractive again for me... 
