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Lens review

Sigma C 56 mm f/1.4 DC DN

22 December 2018
Maciej Latałło

11. Summary


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Pros:

  • good quality casing,
  • sensational image quality in the frame centre,
  • decent resolution on the edge of the frame,
  • low longitudinal chromatic aberration,
  • slight lateral chromatic aberration,
  • lack of problems with spherical aberration,
  • moderate astigmatism,
  • good price/performance ratio.

Cons:

  • untypical performance on the edge of the frame,
  • high distortion,
  • huge vignetting.
Two Sigma models I’ve tested lately, the A 40 mm f/1.4 DG HSM and the smaller C 56 mm f/1.4 DC DN can be positioned on two polar opposites. The first one is a physically huge instrument, constructed without any compromises, with fantastic optics but also a high price tag. The second one is a lightweight, handy optical device, aimed at amateur photographers; its price reflects well their average budget. Small wonder such a lens features many compromises. I could accept the weaker distortion and vignetting performance without a murmur because a fast lens in a small casing has to have a significant brightness loss. Also I am able to understand lack of optics distortion correction in this class of focal lengths; after all camera software can correct that aberration easily and, with such an angle of view, cropped images are hardly an issue.

Still weak image quality on the edge is a drag. There is a big discrepancy between resolution results in the centre and on the edge: while in the frame centre you see resolution records putting to shame the performance of lenses produced by the biggest players of photographic market, on the edge you experience a slump as the lens never reaches 60 lpmm. Perhaps it is not a significant problem for an instrument which is going to be used to take portraits or a shallow depth of field shots; still there are uses where even performance across the frame is more than advisable, even for such a focal range as this one.

All the remarks, presented above, don’t change my very positive assessment of the tested Sigma. It is another excellent optical instrument, offered at a sensible price; it shows that pricing of other producers of mirrorless devices is really over the top.