LensTip.com

Lens review

Sigma A 24 mm f/1.4 DG HSM

8 March 2015
Arkadiusz Olech

7. Coma, astigmatism and bokeh

The coma correction is the first serious slip-up of the Sigma 1.4/24. The slight influence of coma is visible even in the corners of the APS-C/DX sensor but the situation on full frame is simply outrageous. If by f/1.4 and f/2.0 the coma is corrected so badly it is difficult to get a good image resolution on the edge of a big detector.

In order to defend the Sigma a little you can say the Canon and the Nikkor in this category had equally pathetic results; the Samyang was definitely the best of all 1.4/24 class lenses although also in its case the coma correction still couldn’t be called good.

Center, f/1.4 Corner APS-C, f/1.4 Corner FF, f/1.4
Sigma A 24 mm f/1.4 DG HSM - Coma, astigmatism and bokeh Sigma A 24 mm f/1.4 DG HSM - Coma, astigmatism and bokeh Sigma A 24 mm f/1.4 DG HSM - Coma, astigmatism and bokeh
Center, f/2.0 Corner APS-C, f/2.0 Corner FF, f/2.0
Sigma A 24 mm f/1.4 DG HSM - Coma, astigmatism and bokeh Sigma A 24 mm f/1.4 DG HSM - Coma, astigmatism and bokeh Sigma A 24 mm f/1.4 DG HSM - Coma, astigmatism and bokeh


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The astigmatism, understood as an average difference between horizontal and vertical MTF50 values the Sigma manages much better than the coma. The value of that aberration measured by us amounted to 7% - it is the same result as that of the Nikkor 1.4/24G but noticeably higher than that of the Canon 1.4/24L which astigmatism level was just 2%.

It would be difficult to complain about the appearance of defocused light points. The light spread inside them is very even, without any noticeable local extremes. Still there are two things worth emphasizing. Firstly, the circles in the full frame corners by f/1.4 and f/2.0 are truncated which is a symptom of significant mechanical vignetting. Secondly, the exaggerations stemming from the wide angle of view make the images longer; as a result some photos with many lights in the blurry areas might seem less pleasing to the eye.

Center, f/1.4 Corner APS-C, f/1.4 Corner FF, f/1.4
Sigma A 24 mm f/1.4 DG HSM - Coma, astigmatism and bokeh Sigma A 24 mm f/1.4 DG HSM - Coma, astigmatism and bokeh Sigma A 24 mm f/1.4 DG HSM - Coma, astigmatism and bokeh
Center, f/2.0 Corner APS-C, f/2.0 Corner FF, f/2.0
Sigma A 24 mm f/1.4 DG HSM - Coma, astigmatism and bokeh Sigma A 24 mm f/1.4 DG HSM - Coma, astigmatism and bokeh Sigma A 24 mm f/1.4 DG HSM - Coma, astigmatism and bokeh
Center, f/2.8 Corner APS-C, f/2.8 Corner FF, f/2.8
Sigma A 24 mm f/1.4 DG HSM - Coma, astigmatism and bokeh Sigma A 24 mm f/1.4 DG HSM - Coma, astigmatism and bokeh Sigma A 24 mm f/1.4 DG HSM - Coma, astigmatism and bokeh