The resolution test (resolution meaning here the MTF50 function values) of the Sigma A 135 mm f/1.8 DG HSM was based on RAW files from the Canon EOS 5D Mark III. In the case of that reflex camera the decency level is situated near 30-32 lpmm and the best fixe-focal lenses can reach as high as 45-48 lpmm. You should also add that the resolution record on that sensor not so long ago belonged to the Zeiss Otus 1.4/28 (49.2 lpmm), but then was beaten by the Sigma A 85 mm f/1.4 DG HSM and currently amounts to 49.7 lpmm just a tad higher.

Let’s compare to that the result of another fixed-focal Sigma prime; the values we got in the frame centre, on the edge of the APS-C/DX and on the edge of the full frame presents a graph below.



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Honestly, what I am supposed to write here? My admiration scale ended with the Sigma A 1.4/85 and the results of this lens are even better…Let me word it this way: if the Sigma in the frame centre performed as well as on the edge of full frame I would still enthuse about what a brilliant lens fell into my hands. Mind you in the centre the Sigma is noticeably sharper than on the edge.

Out of chronicle’s duty I add that the new record reached by the tested lens by f/2.8 amounts to 51.6 lpmm. The introduction to this chapter is going to be modified again.

At the end of this chapter traditionally we present crops taken from photos of our resolution testing scene saved as JPEG files.