This Sigma 50mm f/1.4 DG HSM Art lens ($949) review is written by Marc Rogoff (www.marcrogoff.com):
I recently purchased the new Sigma 50mm 1.4 DG Art lens intended to replace my Nikon 50mm 1.4G. Whilst the Nikon is a perfectly good lens it tends to be a bit slow focussing and it was always a bit soft towards the edges of the frame (not ideal for portraits as eyes end up out of focus if you are shooting quite open). I wanted a lens that could support the kind of work I do which tends to be either very tight depth of field or lots of depth of field. It needed to be sharp from edge to edge at all apertures ideally – a difficult remit for any lens.
