Get the Sigma 24mm f/1.4 DG HSM Art at B&H Photo.
For anyone looking for a 24mm autofocus lens for Nikon, this is a must-read. In DAP:
Presented with HD and UltraHD images up to actual pixels for the DX frame area from f/1.4 through f/13, along with a large crop at those apertures also. Assesses focus shift, color aberrations and overall performance at a reproduction ratio of about 1:11.