Sigma 150 mm f/2.8 APO EX DG OS HSM Macro review - Image resolution

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Sigma 150 mm f/2.8 APO EX DG OS HSM Macro

24 August 2011

Arkadiusz Olech

4. Image resolution

The resolution test of the Sigma 150 mm f/2.8 APO EX DG OS HSM Macro was based on RAW files from the Nikon D3x full frame reflex camera. The measurement errors ranged from 0.2 to 1.0 lpmm. It’s worth remembering here that the decency level in the case of tests performed on the D3x is situated near 30-31 lpmm and the best fixed-focal lenses can reach results near 46-47 lpmm. It should be also mentioned here that the decency level, chosen by us here, is really only a conventional value. We set it assuming that the level reached near f/16 aperture would be a good resolution indicator. If you close down the aperture more the diffraction will degrade the image to such an extend that it will seem rather fuzzy. Of course you should remember that every user has his/her own image resolution requirements so for some people these 30-31 lpmm will be fully acceptable and for others – not quite.

Let’s check how the tested lens fares in the frame centre, on the edge of the APS-C sensor and on the edge of full frame.

Sigma 150 mm f/2.8 APO EX DG OS HSM Macro - Image resolution

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It can be noticed at once that even at the maximum relative aperture the lens doesn’t have any problems with generating images of good quality. On stopping down the situation becomes even better and by f/5.6 the Sigma reaches the level of 44 lpmm. On the one hand you can be a bit disappointed because macro lenses often dazzle with record-breaking results. On the other hand you really shouldn’t carp about the performance here. The quality of the image is very good, momentarily even splendid, and these values are still better than those of the predecessor, so praised by us before.

The question why there are no record-breaking results in the frame centre is answered by the performance on the edge of the frame of the smaller and the bigger sensor. The values we see there are really excellent. The image is useful already at the maximum relative aperture and on stopping down it is hardly worse than that in the centre. By f/5.6, on the edge of the full frame sensor we get as high as over 40 lpmm; such results are so good that I really can’t remind myself of any other lens which has performed better on full frame. Even the Canon 100L Macro, so praised by us, on the edge of full frame got to maximum 38 lpmm and that result was, after all, reached on the EOS 1 Ds MkIII, which, with good lenses attached, can produce MTFs higher by 1-2 lpmm than the Nikon D3x. We can state that the results of the Sigma on the edge of the frame are about 10% better than those of the splendid Canon.

Apparently Sigma knew what it was doing. There are no records in the frame centre but the level still remains high. There are records on the edge, though, so the image is of very good quality across the frame which is important if you e.g. photograph the reproductions.

The crops below were taken from the frame centre of our test chart.