Sigma A 14 mm f/1.8 DG HSM
4. Image resolution
Let’s check how another prime produced by Sigma compares here – its result in the frame centre, on the edge of the APS-C/DX sensor and on the edge of full frame presents the graph below.
Please Support UsIf you enjoy our reviews and articles, and you want us to continue our work please, support our website by donating through PayPal. The funds are going to be used for paying our editorial team, renting servers, and equipping our testing studio; only that way we will be able to continue providing you interesting content for free. |
- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
The frame centre is similar to the results we have seen in tests of any other Art series prime devices. Already at the maximum relative aperture the MTFs reach 42 lpmm and on stopping down they even increase to a peak of over 47 lpmm by f/4.0. It is a level practically identical to those of other Art series lenses we praised so much (maximum results of 47 lpmm got also e.g. the 1.4/20, the 1.4/35 and the 1.4/50 models).
What’s interesting the best value the Sigma got in this category is just slightly higher than the result of the Samyang 14 mm f/2.8 ED AS IF UMC but noticeably better than the result of the Irix 15 mm f/2.4 Blackstone
The edge of the APS-C/DX sensor seems to be beyond reproach. With such extreme parameters the producers still managed to guarantee good image quality right from the maximum relative aperture. Mind you, the competition in that segment is fierce. Even though the Sigma fares the best near f/2.8 because it is the fastest and, on stopping down to f/1.8, its optical aberrations are noticeably limited, on further stopping down the Samyang 2.8/14 and the Irix 2.4/15 can actually reach higher resolution levels – the Samyang gets to 40 lpmm and the Irix can even exceed that value slightly. The maximum result of the Sigma is less than 39 lpmm. As you see the values differ just slightly, being almost on a borderline of measuring error levels but, officially, the Sigma is the weakest at that point.
The performance on the edge of full frame shows that the Samyang is really a very serious rival. The Irix fared the weakest here although, because of the narrowest angle of view, its task was also the easiest. The Samyang, though, already near its maximum relative aperture (f/2.8) brushed against the usefulness level. The faster Sigma has to be closed down to near f/4.0 in order to achieve that much. Instead that lens provides the best image quality in that part of the frame because on even more pronounced stopping down it reaches over 34 lpmm. The peaks of the Samyang and the Irix were by several lpmm lower.
It’s also worth mentioning that the Canon EF 14 mm f/2.8L USM II, even if the most expensive in this group, was the weakest on the edge of the frame even if it could defend itself well in the frame centre.
To sum up this chapter I can write without any hesitation that the Sigma A 14 mm f/1.8 confirmed the high quality of Art line lenses. It was very difficult, to guarantee a sensational image quality in the frame centre up from the maximum relative aperture, but the Sigma carried out its task to perfection. Of course you can wonder whether the performance on the edge of full frame could have been a bit better but the lack of direct rivals and appropriate material for comparisons makes it difficult to draw any binding conclusions.
At the end of this chapter, traditionally, we present crops taken from photos of our resolution testing chart, saved as JPEG files.
| Canon 5D MkIII, JPEG, 14 mm, f/1.8 |
 |
| Canon 5D MkIII, JPEG, 14 mm, f/4.0 |
 |
