Sigma have been a very well known name in the photography world for many years. The range of focal lengths and camera mounts available is only matched by the number of different opinions there are about their quality. It's not unfair to say that what has let Sigma down in the past is the enormous variation there can be between two lenses that are seemingly identical.
With the introduction of their ART series of lenses this has all changed. This new range has turned the phot