How to use your new digital camera
The Sigma 50mm f/1.4 costs more than the equivalent Canon and Nikon lenses. It's a big and heavy lens, having a 77mm filter thread and weighing in at 505g. That's getting on for twice the weight of the Canon and Nikon lenses, but it's certainly not uncomfortably heavy, and build quality feels particularly strong.
The ring-type ultrasonic autofocus system is ultra-quiet and impressively fast, with similar performance to the Canon 85mm lens in the group. Full-time manual focus override is silky-smooth. The inner lens barrel extends at shorter focus distances, putting the front element almost flush with the front of the lens at the closest focus distance.
However, the lens comes with a good quality petal-shaped lens hood plus a padded carry pouch. Matched only by the Nikon 50mm lens on test, the Sigma has nine diaphragm blades that produce a very well-rounded aperture.
The Sigma retains sharpness at f/1.4 slightly better than the Canon and Nikon 50mm lenses. However there's a blip at f/2.8 where sharpness drops to the same level as the Canon, and the Nikon runs it close at f/11.
Apart from at f/2.8, sharpness is consistent throughout the aperture range and across the whole frame, from the centre to the corners of the image. Helped by the oversized front element, vignetting is negligible. For a prime 50mm lens, pincushion distortion is a bit on the high side.
There's a dip in sharpness at f/2.8, but the Sigma acquits itself very well at f/1.4-1.8 and at medium to small apertures.
Colour fringing is extremely low at either end of the aperture range, and the only real peak is at f/2.8, where it's still minimal.
As with the other 50mm lenses on test here distortion is low, but slight pincushioning can be apparent in some images.
Image test verdict
Apart from at f/2.8 where there's a dip in sharpness and a peak in colour fringing, this Sigma lens delivers very good image quality indeed.