Hello, My daughter ended up getting a camera. I tried to persuade her to get something like an EM10-II but she ended up with a Nikon DX format system. I think she has an 18-55mm kit lens with it. I wanted to see if there are any primes that some Nikon shooter might recommend. Something small and fast and in that 40-50mm range. I assume about 27 - 30mm would be good. Is the Sigma 30/1.4 a nice lens for Nikon? Thanks for any help. I have zero Nikon exposure.