The 50mm F1.4 is a member of Sigma's premium 'EX' lens line, and build quality feels genuinely excellent, at least on a par with any of the other 50mm F1.4s currently available. The lens mount is metal, and the body apparently constructed of high-quality plastics, with Sigma's familiar textured EX finish. The body design is unique in this class, and similar to Sigma's 30mm F1.4; the optical assembly is entirely enclosed within the outer lens barrel which includes the filter ring, and moves backwards and forwards as a unit by about 8mm for focusing. This means that the front element is quite deeply recessed at longer focus distances, offering a degree of shielding from stray light even when the hood is not mounted.
On the camera
There's no getting away from the fact that the Sigma is simply huge for a 50mm F1.4, even managing to look large on the chunky Canon EOS 5D body (above left), and positively dwarfing smaller cameras such as the EOS 450D (above right). Despite this it handles well, with the focusing ring well-positioned towards the front of the barrel, and falling naturally to hand.
This lens uses Sigma's 'HyperSonic Motor' (HSM) variant of ultrasonic focusing for fast, accurate and near-silent operation. The good news is that this will be provided for users of all lens mounts, and (for the first time on a 50mm lens) offers AF with Nikon's D40(x)/D60 bodies. Unfortunately it also means that users of older Pentax DSLRs which don't support SDM lenses will lose out, and only be able to focus manually; in other words, the lens is effectively of KAF-3 mount specification.
In real life use, our Canon-mount sample performed well, with AF positive and reasonably fast under all but the most difficult conditions, using a variety of bodies from the 450D to the 5D (although as always, it must be noted that focus speed and accuracy is dependent upon a number of variables, including the camera body used, subject contrast, and light levels). However focusing was noticeably slower than Canon's own EF 50mm F1.4 USM and EF 50mm F1.8 II lenses, so this is still an area in which Sigma can improve. Focus accuracy was generally impressive, although with a certain tendency towards slight front-focus at close distances and F1.4, especially with low-contrast subjects. The lens also shows some evidence of a slight focus shift to the rear on stopping down, which meant our sample focused correctly when set to F2.
Lens body elements
Reported aperture vs focal length
This lens allows an aperture range from F1.4 to F16 to be selected.