Lens review

Pentax smc D FA 100 mm f/2.8 Macro WR

18 March 2011
Arkadiusz Olech

4. Image resolution

As we already mentioned in the introduction, the resolution test of the Pentax smc D FA 100 mm f/2.8 Macro WR was based on RAW (PEF) files from the Pentax K-5 camera. It can provide, approximately, the same MTFs as the Canon 50D or the Olympus E-3 so we can say the decency level will be situated at 34-35 lpmm here and the best lenses will reach results on the level of 51-52 lpmm.

The graph below shows the performance of the tested lens in the frame centre and on the edge of the APS-C sensor.

Pentax smc D FA 100 mm f/2.8 Macro WR - Image resolution

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When it comes to the frame centre, the lens deserves nothing but praise. Already at the maximum relative aperture it reaches the result of almost 43 lpmm which means it is able to generate fully sharp images. On stopping down to f/4.0 we enter the level a tad over 50 lpmm.. The peak of its possibilities (52.4 lpmm) the Pentax reaches by f/5.6. So praised by us and noticeably more expensive Canon 2.8/100L fared a bit better at the maximum relative aperture, where it had almost 46 lpmm. From f/4.0, though, the results of both lenses are, within the margin of error, the same, remaining of course excellent all the time.

The performance on the edge of the frame can be described in similar terms. Even at the maximum relative aperture we get the value of about 36 lpmm so a bit over the decency level. Here also the Pentax gives in to a bit more expensive Canon which, by f/2.8, had the result of 41 lpmm. The situation is reversed, though, by f/4.0 and f/5.6 - the Pentax is a bit sharper than the Canon there.

It’s also worth noticing that the resolution of the Pentax 2.8/100 WR was tested on three charts of different sizes so the lens was positioned in three different distances from the target. We didn’t observe any differences in results got on particular charts.

To sum up the results the Pentax smc D FA 100 mm f/2.8 Macro WR in the resolution category are excellent. It would be difficult to expect anything else, though. In this class of lenses there are no weaklings. Practically all macro devices with f/2.8 aperture and focal lengths ranging from 90 to 105 mm reached in our tests good or simply splendid results. The Pentax couldn’t have afforded a slip-up here and fortunately there wasn’t one.

The photos below show crops from the centre of our testing charts; they were saved as unsharpened JPEG files along RAW files.

Pentax smc D FA 100 mm f/2.8 Macro WR - Image resolution