Sigma C 24 mm f/2 DG DN – first impressions and sample images

9 September 2021
Maciej Latałło

3. Autofocus and several words about optical properties

Sample shots, presented in the last chapter of this article, don't leave any doubts about optics quality you deal with. In the frame centre images seem to be very sharp already from the maximum relative aperture. The new Sigma seems to continue the excellent streak of its 35 and 65 mm brothers. Believe me, I can hardly wait for the test of a final specimen which will allow us to check on the real possibilities of this new Sigma lens.

The autofocus of the Sigma C 2/24 mm combined with the Sony A7R III is completely noiseless and quite quick. Running through its distance range and confirming the right position takes about 0.5-0.6 of a second. This time doesn't depend on what side you start from or whether you work in good or poor lighting conditions. Its performance might be called quite comfortable but don't forget constructors usually work hard till the very end to improve the efficiency of autofocus so we hope the final version will fare even better.

In a case of a lens with such an angle of view and a significant depth of field we didn't expect any slip-ups concerning the accuracy of the focusing mechanism and we were right – the lens performed equally well in studio conditions and outside.

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Performance against bright light is another thing easy to correct even in the last production stages – you can always modify slightly the coatings, blacken the interior better, add apertures and internal baffles. Such treatment would be highly advisable in case of the Sigma C 2/24 because you can catch some flares with it, especially when the sun is positioned inside the frame and the aperture – stopped down more significantly.

Sigma C 24 mm f/2 DG DN – first impressions and sample images - Autofocus and several words about optical properties

Sample shots show clearly that the constructors didn't bother with vignetting correction and it might exceed even 3 EV. Still, we must emphasize the fact that in the case of the Contemporary series instruments Sigma optics specialists have a clear list of priorities and they follow them to the dot. First come image quality, sensible dimensions, and a moderate price tag – these three things have to be achieved even if they have to pay for them with higher vignetting and distortion. After all, these two aberrations are the easiest to correct with camera's software.

As we've already mentioned distorion – you can notice distinct barrel variant of this aberraion in sample shorts. It seems the Sigma is close to the performance of the Tamron 24 mm f/2.8 Di III OSD M 1:2 which distortion was on a level of -5%. It seems the correction of that aberration really wasn't a priority for Sigma specialists.