Lens review

Sigma A 85 mm f/1.4 DG HSM

16 November 2016
Arkadiusz Olech

4. Image resolution

The resolution (in terms of the MTF50 function) test of the Sigma A 85 mm f/1.4 DG HSM was based on RAW files from the Canon EOS 5D Mk III. In the case of that reflex camera the decency level is situated near 30-32 lpmm and the best fixed focal length lenses can reach 45-48 lpmm. It’s worth adding that the resolution record for this sensor not so long ago belonged to the Canon EF 35 mm f/1.4 USM II and amounted to 48.0 lpmm but it was beaten by the Zeiss Otus 1.4/28 so now it amounts to 49.2 lpmm.

Let’s check how the tested Sigma compares here – its results in the frame centre, on the edge of the smaller APS-C/DX sensor and on the edge of full frame are presented below.

Sigma A 85 mm f/1.4 DG HSM - Image resolution

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There’s no need to beat about the bush: the results are simply brilliant, no matter where you look. In the centre of the frame, already at the maximum relative aperture, you get a sensational value exceeding 42 lpmm. What’s more, the previous resolution record belonging to the Otus 1.4/28 the Sigma managed to beat at three next apertures, examined by us so f/2.0, f/2.8 and f/4.0. Officially the highest result – that of 49.7 ±0.4 lpmm - was reached by f/2.8 and it becomes our official new record for the sensor of the EOS 5D Mark III.

The performance on the edge of the frame is equally sensational. It’s enough we say that on the very edge of the very demanding full frame the Sigma is sharper than many old system “primes” in the frame centre and such lenses were considered very good in their time.

Instead of a summary let’s show another graph, comparing the performance in the frame centre of the Sigma and other contemporary, fast 85 mm lenses tested on detectors with the same pixel density.

Sigma A 85 mm f/1.4 DG HSM - Image resolution

The graph leaves no doubts. It proves that currently Sigma is able to produce the sharpest optics on the market in this class of equipment.

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, 85 mm, f/1.4
Sigma A 85 mm f/1.4 DG HSM - Image resolution
Canon 5D MkIII, JPEG, 85 mm, f/2.8
Sigma A 85 mm f/1.4 DG HSM - Image resolution