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Lens review

Sigma A 28 mm f/1.4 DG HSM

21 January 2019
Maciej Lata││o

8. Vignetting

First let’s check how the Sigma A 1.4/28 performs in this category on the smaller sensor of the Canon 50D – appropriate thumbnails you can find below.

Canoná50D, f/1.4 Canoná50D, f/2.0
Sigma A 28 mm f/1.4 DG HSM - Vignetting Sigma A 28 mm f/1.4 DG HSM - Vignetting


No reasons to worry– at the maximum relative aperture the vignetting amounts to 27% (−0.89 EV), and by f/2.0 and f/2.8 it decreases to an imperceptible value, 9% (−0.28 EV) and 7% (−0.22 EV) respectively.

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Now let’s check how the situation changes when you progress to full frame – below you can find images produced with the help of the Canon EOS 5D Mark III.

Canon 5DáIII, f/1.4 Canon 5DáIII, f/2.0
Sigma A 28 mm f/1.4 DG HSM - Vignetting Sigma A 28 mm f/1.4 DG HSM - Vignetting
Canon 5DáIII, f/2.8 Canon 5DáIII, f/4.0
Sigma A 28 mm f/1.4 DG HSM - Vignetting Sigma A 28 mm f/1.4 DG HSM - Vignetting


In this case vignetting is, unfortunately, huge. At the maximum relative aperture you lose as much as 64% of light (−2.94 EV) in frame corners. What’s interesting, it is a result better than 68% achieved by the bigger Otus. Both the Sigma and the Otus are weaker in this category than the Nikkor AF-S 1.4/28 as its result was 53%.

Fortunately the vignetting of the Sigma decreases swiftly on stopping down. By f/2.0 its value is 40% (−1.49 EV), and by f/2.8 it reaches 21% (−0.68 EV). By f/4.0 the light fall-off drops to an almost imperceptible value of 12% (−0.38 EV) and then it stops reacting to further stopping down of the aperture.

Canon 5DáIII, JPEG, f/1.4
Sigma A 28 mm f/1.4 DG HSM - Vignetting