To answer the OP. In terms of recommendations, the three outstanding performers are the Nikon 14-24f2.8 and 16-35f4 plus the Tokina 16-28f2.8. Please feel free to regard this as biased opinion since I am going all-crop I have a Tokina 16-28 up for sale here on TP. The unbiased opinion, however, is that the Tokina is very close to the 14-24 in most respects but at a fraction of the price and it is well worth checking out. A quick google will confirm the above. Good luck with your search.