I am looking for an ultra wide for a Nikon D750 and being just a hobby photog and no longer working, can't justify the price of the Nikon 14-24 and even the Tamron 15-30, although it is quite tempting. Has anyone had any experience with the Tokina AT-X 16-28 f2.8 pro fx? I do want a fast lens to use for star photography. We do have the Tokina 11-16 f2.8 which is a good lens. I have read it is usable on FF at 15 an 16 without too much loss in IQ on the edges and not too much vignetting. But, if shooting stars, one of us will still have the D7100 and need the 11-16.