Sigma 20mm f/1.4 DG HS M I A £630/$900
This Sigma goes extra-wide in every way
A world first for SLR lenses, this Sigma Art lens combines an ultra-wide viewing angle with a wide aperture rating of f/1.4. This is made possible by a highly complex, large-diameter double aspherical element, which is a challenge to manufacture.
Considering this, the purchase price is very reasonable, but you do pay for it in size and weight. It’s the biggest lens in the group by quite a margin and, at 950g, nearly three times the weight of the Nikon 20mm f/1.8 lens.
Like the Samyang 14mm lens, the Sigma 20mm has a built-in lens hood that protects the bulbous front element from physical knocks, as well as helping to reduce ghosting and flare. Again, fitting filters isn’t straightforward, but Lee Filters makes an adaptor for both lenses, to enable use of its SW150 Mk II filter system. Performance Given the extreme viewing angle, image quality is excellent, with superb sharpness right into the corners of the frame, negligible colour fringing and fairly modest vignetting despite the fast f/1.4 aperture rating.