LensTip.com

Lens review

Sigma A 24-70 mm f/2.8 DG DN

22 January 2020
Arkadiusz Olech

8. Vignetting

First let's check how the Sigma A 24–70 mm f/2.8 DG DN fares on the smaller APS-C sensor – appropriate thumbnails you can find below.

A7R II, APS-C, 24 mm, f/2.8 A7R II, APS-C, 24 mm, f/4.0
Sigma A 24-70 mm f/2.8 DG DN - Vignetting Sigma A 24-70 mm f/2.8 DG DN - Vignetting
A7R II, APS-C, 45 mm, f/2.8 A7R II, APS-C, 45 mm, f/4.0
Sigma A 24-70 mm f/2.8 DG DN - Vignetting Sigma A 24-70 mm f/2.8 DG DN - Vignetting
A7R II, APS-C, 70 mm, f/2.8 A7R II, APS-C, 70 mm, f/4.0
Sigma A 24-70 mm f/2.8 DG DN - Vignetting Sigma A 24-70 mm f/2.8 DG DN - Vignetting


As you see there are no problems whatsoever at any focal length. Even employing the widest angle available and the f/2.8 aperture you have to take into account the loss of 16% (−0.50 EV) of light in frame corners. The problem disappears practically completely by f/4.0 where it reaches just 10% (−0.31 EV).


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The situation is even better in the middle of the focal range – by f/2.8 and f/4.0 we got the following values: 13% (−0.40 EV) and 7% (−0.20 EV) respectively.

At the maximum focal length and by the maximum relative aperture the vignetting amounts to 15% (−0.48 EV) and it drops to an imperceptible level of 6% (−0.18 EV) on stopping down the aperture to f/4.0.

Now it's time to check how the tested lens performs on full frame detector – appropriate photos you can find below.

A7R II, FF, 24 mm, f/2.8 A7R II, FF, 24 mm, f/4.0
Sigma A 24-70 mm f/2.8 DG DN - Vignetting Sigma A 24-70 mm f/2.8 DG DN - Vignetting
A7R II, FF, 45 mm, f/2.8 A7R II, FF, 45 mm, f/4.0
Sigma A 24-70 mm f/2.8 DG DN - Vignetting Sigma A 24-70 mm f/2.8 DG DN - Vignetting
A7R II, FF, 70 mm, f/2.8 A7R II, FF, 70 mm, f/4.0
Sigma A 24-70 mm f/2.8 DG DN - Vignetting Sigma A 24-70 mm f/2.8 DG DN - Vignetting


We don't hesitate to say the situation here is simply dramatic. Slimming down the lens by force, just so it appears more slender than the reflex camera version, makes itself felt here at every step. At the most difficult combination of 24 mm focal length and f/2.8 aperture you lose as much as 74% (−3.91 EV) of light in the frame corners.

I understand that vignetting is easy to correct but it is just going over the top. In this case, if you take a photo at ISO 200 and correct vignetting reaching almost 4 EV in the frame corners the image quality will become almost like at ISO 3200 so definitely not up to scratch. Everything comes at a price...

Let's remind here that the reflex camera Sigma 24-70 mm had a noticeably lower result in this category, amounting to 57%, and the vignetting of theTamron, a bit easier to correct, was still 66%.

Bad news don't end because vignetting decreases quite slowly on stopping down. By f/4.0 it is 62% (−2.78 EV), by f/5.6 it still reaches 47% (−1.83 EV), and by f/8.0 it gets to 34% (−1.22 EV). It remains noticeable even by f/11.0 and f/16.0, where we got the following results: 30% (−1.02 EV) and 29% (−0.99 EV).

The vignetting performance improves a bit in the middle of the focal range but still problems remain there and they are quite serious too, like the result of as much as 60% (−2.63 EV) by f/2.8. By f/4.0 vignetting decreases to 43% (−1.61 EV), a still noticeable level, and by f/5.6 it drops to 28% (−0.93 EV). With a moderate level of that aberration you deal only by f/8.0 and f/11.0 apertures, where it reaches, respectively, 21% (−0.69 EV) and18% (−0.58 EV).

The situation at 70 mm, when compared to that at 45 mm, doesn't improve significantly. By f/2.8 you still deal with 60% (−2.64 EV) of brightness loss in frame corners; that value decreases to 41% (−1.54 EV) on stopping down the aperture by 1 EV. By f/5.6 the vignetting is 26% (−0.87 EV), by f/8.0 it reaches 17% (−0.54 EV), and by f/11.0 it gets to 14% (−0.44 EV).

Sony A7R II, 24 mm, f/2.8
Sigma A 24-70 mm f/2.8 DG DN - Vignetting
Sony A7R II, 45 mm, f/2.8
Sigma A 24-70 mm f/2.8 DG DN - Vignetting
Sony A7R II, 70 mm, f/2.8
Sigma A 24-70 mm f/2.8 DG DN - Vignetting