Conclusion

The Sigma 45mm F2.8 DG DN lens offers quite an unusual standard focal length of 45mm for full-frame mirrorless cameras from Sony, Panasonic, Leica and Sigma themselves.

It's small size and weight make it a perfect match to a small mirrorless camera like the Sony Alpha A7 III that we tested it with.

It offers good sharpness wide-open at f/2.8, excellent build quality and weather-proofing, nice bokeh and fast and quiet auto-focusing, all at a very affordable price.

The Sigma 45mm F2.8 DG DN is tack-sharp in the centre from f/4 onwards, although you need to stop down to f/5.6 to get acceptable results at the edges of the frame. Chromatic aberrations and vignetting are both very well controlled.

The auto-focusing system proved to be quick, reliable and virtually silent on the Sony A7R II that we tested the lens with, and manual focus over-ride at any time is a great feature.

It's shame that the very welcome aperture ring can't be de-clicked for video use, though, as otherwise this lens is well-suited to both shooting stills and movie-making.

Build quality is very good, with the brass lens mount, metal lens barrel, and the sober all-black design adding to the high-quality feel, and Sigma have even generously included a metal circular lens hood.

The modest asking price of the Sigma 45mm F2.8 DG DN is reasonable for such a compact, well-built, high-perfomance lens.

If you're in the market for a small, light standard lens that's perfect for travel and street photography, then the Sigma 45mm F2.8 DG DN should be high on your list of candidates.

Ratings (out of 5)
Design	5
Features	3.5
Ease-of-use	4.5
Image quality	4.5
Value for money	4.5