For the life of me, I can't work out which one to get. Predominantly for star trails and landscapes. I know the Tokina DX II's main improvement is the autofocus motor in the lens, but I've got a D7100, so it doesn't really matter.
The Sigma is cheaper and has a bigger range than the Tokina, but I like the speed of the Tokina, especially for star trails.
I'm also eyeballing the Rokinon / Samyang 14mm f/2.8, but it's fixed to 14mm, and you can't use a screw on filter - the lens bulges out like a squeezed cane toad's.
Any suggestions most welcome.