It is not possible to make direct comparisons between the Nikon, Sony and Canon lenses because a different camera system has been used for each to record our resolution charts.
However, as close a comparison as possible has been used, with the 24-million-pixel Nikon D600 being used for the Sigma and Nikon lenses, the 24-million-pixel Alpha 99 for the Sony lens and the 22.3-million-pixel Canon EOS 5D Mark III for the Canon and Tamron lenses.
Our resolution charts indicate centre sharpness for each of the lenses at the optimum f/5.6 and f/11 settings, and it is difficult to note any differences between them at all.
The brand lenses show slightly better contrast, with the Sigma lens a tad softer, but all five models are able to resolve up to 30 marker on our charts. This is close to the performance of the Sigma 105mm f/2.8 macro lens that we use to record the charts in our camera tests, so these are impressive results all round.
The f/2.8 and f/22 apertures provide a greater test for each lens, being the ‘softest’ settings. Again, resolved detail is similar, but there are more noticeable differences. For example, the Sigma lens is the softest at f/2.8, showing less contrast and a sort of ‘glow’ around object edges.
The Tamron lens is able to match the brand lenses, which are impressively crisp given that f/2.8 is the fastest aperture available.
A big test of the quality of a lens is at the edges of the frame, with poor-quality lenses usually having soft and distorted detail. Having recorded the same scenes with all five lenses, each model puts in an impressive performance.
There is a slight difference in edge sharpness, which is consistent with the differences in centre sharpness – that is, the Sigma lens is a little softer.
Put simply, each lens is able to carry its solid centre performance to its edges.
Image: All five portraits have been recorded using the 135mm and f/8 settings on each lens, to achieve the best and sharpest quality. At this setting, any differences in sharpness between the lenses is so minimal that it is difficult to tell the lenses apart. The impressive centre sharpness is taken to the edges, too, with detail in the shirt cuff being crisp right to the edge of the frame. When pushed to the wide f/2.8 setting, the differences are more obvious – the Sigma lens has less contrast and is sightly softer than all the other lenses
