Lens review

Sigma 28 mm f/1.8 EX DG Aspherical Macro

8. Vignetting

At the maximum aperture this aberration will cause us some pain, though, because at this point we lose 39% of light (−1.43 EV). It’s a lot for such a small detector. Fortunately on stopping down we see the situation improving swiftly. By f/2.0 the brightness loss in the frame corners decreases to 33% and by f/2.8 – to a not very bothersome level of 14%. By f/4.0 and f/5.6 this aberration stop being a nuisance because it reaches 10-11% there.

Now let’s assess the situation on full frame.

Wide angle, good fastness and a big detector – those are factors that favour the vignetting. This time we see the same story. At the maximum relative aperture in the frame corners we lose as much as 59% of light (−2.57 EV). This result is high but we’ve already been accustomed to it on full frame.

On stopping down to f/2.0 the vignetting decreases to 54% and by f/2.8 it amounts to 34%. Moderately bothersome or not bothersome results we see only by f/4.0 and f/5.6 where the vignetting is 25% and 19% respectively. On further stopping down we see the vignetting changing only slightly.