I made some unscientific test shots in the pool the other day, to see how the Tokina 10-17 FE performs on a 24 mp full frame camera behind two different dome ports.
Camera: Nikon D600, Tokina on 15mm, ISO 6400 (ambient light), Aperture priority. Focus point was at the center. I ran the raw files through Lightroom to adjust white balance and lighting. No cropping, sharpening or noise reduction were applied. I sharpened for screen upon exporting to jpegs.
First three shots using the Tokina 10-17FE behind Subal 4" minidome (DP-54 B)
Last three shots same lens behind Subal 6" dome (DP-SW B). No extension rings.
I guess f11 is the limit. At 15mm behind the 6" port the dome shade is visible in the corners (slight vignetting), limiting it's use to the long end.