I have got the new Tamron 15-30/2.8. However, it does NOT work properly on my D800, i.e. the AF mostly does not work at 15mm focal lenghth, at other lengths it works, but it fails to produce sharp images on the entire frame (about 10 % of the photo are sharp, rest is not). On the D600 it is a little better, estimated 70 % sharp images, on the D750 about 80-90%. Focusing with Liveview does not help either