Sigma C 12 mm f/1.4 DC review - Vignetting

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Sigma C 12 mm f/1.4 DC

28 October 2025

Maciej Latałło

8. Vignetting

When it comes to lenses designed to cooperate with smaller APS-C/DX sensors we often are asked whether or not they can cover full frame. Photos below prove that the Sigma 1.4/12 won't be able to be used with bigger detectors but nobody could have expected it.

A7R IIIa, FF, f/1.4	A7R IIIa, FF, f/8.0

Now let's check how the Sigma C 12 mm f/1.4 DC deals with correction of vignetting on the APS-C/DX sensor; appropriate thumbnails you can find below.

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A7R IIIa, APS-C, f/1.4	A7R IIIa, APS-C, f/2.0

A7R IIIa, APS-C, f/2.8	A7R IIIa, APS-C, f/4.0

At the maximum relative aperture vignetting is very high, reaching a level of 67% (-3.19 EV). Here the Sigma fares weaker than its rivals: the Viltrox 1.4/13, on uncorrected files showed a level of 55%, and the result of the Sony 1.8/11 amounted to 62%. In order to defend the Sigma a bit you can say that its field of view is wider than that of the Viltrox and its aperture a bit faster than that of the Sony.

Stopping down the aperture to f/2.0 decreases vignetting to a still high level, that of 51% (-2.06 EV). You also won't get any problems to notice it by f/2.8, where it amounts to 35% (-1.25 EV). More or less sensible values start from f/4.0, where our measurements provided a result of 25% (-0.85 EV). By f/5.6 and f/8.0 we got, respectively, 22% (-0.73 EV) and 21% (-0.70 EV). Further stopping down of the aperture doesn't provide any measureable effects.

Sony A7R IIIa, APS-C, JPEG, f/1.4

It's also worth checking how vignetting looks on corrected JPEG files, after all you deal with a field of view slightly exceeding 100 degrees and it is completely devoid of distortion. Appropriate thumbnails you can find below.

A7R IIIa, APS-C, f/1.4	A7R IIIa, APS-C, f/2.0

A7R IIIa, APS-C, f/2.8	A7R IIIa, APS-C, f/4.0

This time at the maximum relative aperture this aberration reaches 61% (-2.69 EV). Once again in this place the Sigma has to admit defeat. The Viltrox showed a level of 37% and the Sony – 57%.

By f/2.0 vignetting decreases to 42% (-1.60 EV), by f/2.8 to 28% (-0.93 EV), and by f/4.0 it drops to a moderate level of 21% (-0.68 EV). Further stopping down of the aperture doesn't provide any measureable effects.