Sigma C 28-70 mm f/2.8 DG DN review

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Sigma C 28-70 mm f/2.8 DG DN

24 March 2025

Maciej Latałło

5. Chromatic and spherical aberration

Chromatic aberration

The optical construction of the Sigma C 28-70 mm f/2.8 DG DN features as many as four elements made of low dispersion glass of different degrees so we assumed it would deal with correction of the longitudinal chromatic aberration well. It is indeed the case – you don't notice any symptoms of this aberration either at 50 mm or at 70 mm, its influence on the image quality is slight, visible only by f/2.8.

Sigma C 28-70 mm f/2.8 DG DN - Chromatic and spherical aberration

What about the lateral chromatic aberration? The appropriate graphs showing the edge of the APS-C sensor and the edge of full frame we present below.

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It's clear that the tested lens doesn't experience any serious problems here. In the majority of different combinations of focal lengths and apertures the results are positioned below 0.04% so they belong to very low values. What's more, they never exceed 0.06% so chromatic aberraion doesn't even approach medium values. In this category the Sigma performs much better than the Tamron that featured many problems in this area, especially at the maximum focal length.

A7R IIIa, RAW, 28 mm, f/2.8	A7R IIIa, RAW, 70 mm, f/16.0

Spherical aberration

First photos of this chapter show a slight focus shift effect. Problems with spherical aberration are additionally confirmed by the appearance of out-of-focus circles of light. At both focal lengths there are some differences when you compare images reached before and behind the focus. It's true that these differences aren't very conspicuous but they confirm the fact that the tested Sigma doesn't correct spherical aberration in a perfect way.