Review by Markus Stamm and Klaus Schroiff, published May 2011

Introduction

Unlike other full format 50mm f/1.4 lenses it features a massive front element (77mm filter thread) and it takes advantage of an aspherical element and both aspects are pretty unique design decisions for a 50mm f/1.4 lens. Sigma is obviously quite confident regarding their new baby because they are bold enough to ask a street price beyond the other 50mm f/1.4 AF lenses - around 400€/480US$.

Being a member of Sigma's professional grade "EX" (excellence) lineup, the build quality of the Sigma lens is excellent - the outer body is obviously made of some kind of metal on which our review unit featured the typical Sigma EX coating (crinkle finish).
However, current production units of the lens no longer feature the crinkle finish but a smooth rubber coating instead (also on top of a metal body). The new finish seems to be a better approach in our opinion - it doesn't collect as much dust for instance.

The focus ring is very smooth. Unlike most 50s it has a constant physical length regardless of the focus setting although the inner lens tube moves a little. The front element does not rotate, so using a polarizer is therefore no problem.

The HSM ("Hyper-Sonic-Motor") AF is very fast and virtually silent. AF accuracy is a difficult topic for the Sigma. It seems to suffer from pronounced focus shifts when stopping down ("Residual spherical aberrations", see next page) which is probably the reason why many users report back- or front-focusing issues.

The Sigma AF 50mm f/1.4 EX DG HSM is a G-type lens and thus does not offer an aperture ring.