Lens review

Sigma C 35 mm f/2 DG DN

8 January 2021
Maciej Lata³³o

4. Image resolution

The resolution test (resolution meaning the MTF50 function values) of the Sigma C 35 mm f/2 DG DN Macro was based on RAW files from the Sony A7R II and Sony A7R III cameras. In the case of this kind of detector the decency level we set about 39-41 lpmm and the best fixed focal length lenses have been able to exceed 70 lpmm. So far, two Voigtlander lenses have fared the best: the Apo-Lanthar 65 mm f/2 Aspherical 1:2 Macro (78.5 lpmm) and the Nokton 50 mm f/1.2 (78.6 lpmm). The Sigma A 105 mm f/2.8 DG DN Macro (80.4 lpmm) is very close behind them.

Let's check how the SigmaC 35 mm f/2 DG DN Macro compares – its results in the frame centre, on the edge of the APS-C sensor and on the edge of full frame presents a graph below.

Sigma C 35 mm f/2 DG DN - Image resolution

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In the frame centre the Sigma fares splendidly well. Already at the maximum relative aperture you get a result of almost 55 lpmm – it means images of good quality. Then the resolution improves very quickly on stopping down, by f/4.0 reaching a sensational level of 77.3 lpmm.

In case of wide angle lenses designed for mirrorless cameras you often see a situation when the edge of the frame is weaker and lags significantly behind the results in the centre. Sigma avoided that. On the edge of the APS-C sensor maximum its results reach a very good level of almost 66 lpmm and on the edge of full frame the lens is able to get to 55-56 lpmm.

The situation at the maximum relative aperture is very interesting. The curvature of the field graph looks quite complex – as a result resolution the edge of the APS-C sensor is a bit weaker than the result on the edge of full frame; still, in both cases you land safely above the decency level so you shouldn't complain. Especially that already by f/2.8 the situation returns to normal and the edge of the APS-C sensor becomes sharper.

As a kind of interesting experiment we compared the results of the Sigma in the centre and the results of its rivals - the Zeiss Batis 40 mm f/2 CE and the Sony FE 35 MM F/1.8. An appropriate graph can be found below.

Sigma C 35 mm f/2 DG DN - Image resolution

It is clear that near the maximum relative aperture the Sigma wins when it comes to the best image quality. By f/2.8 all three lenses fare almost identically well and by f/4.0 the Sigma and the Zeiss are a tad better than the Sony despite the fact that they are also slower aperture-wise. Out of these three lenses the Sigma presents itself the best.

At the end of this chapter, traditionally, we present crops taken from photos of our resolution testing chart saved in JPEG format alongside RAW files which we used for the analysis above.

A7R III, JPEG, 35 mm, f/2.0
Sigma C 35 mm f/2 DG DN - Image resolution
A7R III, JPEG, 35 mm, f/4.0
Sigma C 35 mm f/2 DG DN - Image resolution