If you want a 14mm lens for your full-frame mirrorless camera, with autofocus and a maximum aperture of f/1.4, the Sigma 14mm F1.4 DG DN Art is the only game in town. No one else makes anything quite like it, with the closest alternative being the Sony FE 14mm F1.8 GM. Yet despite its large aperture, it’s not wildly expensive: it costs £1,400, compared to £1,300 for the Sony f/1.8 lens.
There are a couple of reasons other brands don’t make a lens this wide with such a fast maximum aperture. Firstly, they are hard to make well. Secondly, with the sort of depth-of-field you get with a 14mm lens, f/2.8 has usually been seen as a large enough opening. Sigma though is aiming this ultra-wideangle optic at night-sky shooters who need to carefully balance their shutter speeds with their ISO settings, so a super-fast maximum aperture makes life very much easier. Indeed, the firm has gone to quite some lengths with its other features
