A competitively priced, digitally optimised lens......
The DG moniker indicates that this is a full-frame compatible lens, while EX indicates that it is one of Sigma’s top marque lenses. The lens has an impressive maximum aperture of f/2.8, dropping to f/45 minimum (f/32 on Nikon or Pentax cameras). This is worth considering if you need maximum depth of field, because the closer you are to a subject, the shallower the depth of field. This is even more true with macro lens, so focus can fall off pretty quickly.
The lens is constructed from 10 elements in 9 groups, and offers a close focus distance of 18.9cm, with a true 1:1 magnification. The lens is digitally optimised with special coatings that are designed to reduce flare and ghosting as well as lateral chromatic aberrations.
The Sigma impresses with a very small minimum aperture, allowing plenty of depth of field, but test charts show it to not be the sharpest lens in comparison with some of its peers. Performance is adequate, with best results at f/11, before the mean MTF results begin to dip. Chromatic aberration results are very good at the centre of the frame with moderate fringing occurring at the corner of the frame.
A good budget lens with reasonable if not stunning performance