Sigma A 17-40 mm f/1.8 DC review - Summary

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Sigma A 17-40 mm f/1.8 DC

25 August 2025

Maciej Latałło

10. Summary

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Pros:

unique parameters,
solid casing,
sensational image quality in the frame centre across the whole focal range,
very good image quality on the edge of the frame,
moderate longitudinal chromatic aberration,
sensible correction of lateral chromatic aberration,
low astigmatism,
sensible performance against bright light,
silent, quick, and accurate autofocus,
slight focus breathing,
sensible appearance of out-of-focus areas,
very good price/performance and price/quality ratio.

Cons:

significant vignetting,
distinct distortion on both ends of the focal range for RAW files.

It seems that we are in the middle of a series of lenses that very narrowly miss the 'Editors' Choice' badge. The Sigma A 17-40 mm f/1.8 DC is another one. It is an excellent lens, with unique parameters and a sensational image resolution across the frame and for all apertures. Taking into account its brilliant performance and great parameters the Sigma is really sensibly priced, as it can be bought for around $920.

Still, I couldn't ignore high distortion which correction was completely abandoned at both ends of the focal range. After all you deal here with a top-of-the-range Art series instrument with a zoom ratio amounting to just 2.35 x. In this situation I feel the optics constructors could have tried a little harder. The combination of high distortion level and significant vignetting, quite understandable with such parameters, made the Sigma lose its chance for our distinction badge.

Of course it doesn't change the fact that you deal here with an excellent lens and its launch I greeted with real joy. Our faithful Readers know very well that I like APS-C/DX-based system and I truly lament the fact that one part of manufacturers neglect them. In this situation I am happy that independent producers are able to save the situation and launch such gems as the Sigma, tested here.