Lens review

Pentax smc FA 35 mm f/2 AL

20 July 2010
Arkadiusz Olech

4. Image resolution

The resolution test of the Pentax 2/35 was based on the strength of RAW files from a Pentax K20D. It’s worth noticing here than the 14-megapixel sensor of that camera works similarly as 10-megapixel CCD sensors from such bodies as the Pentax K10D, the Nikon D200 or the Sony A100 and it allows us to compare intersystem results. You just have to remember that the results from an 8-megapixel Canon 20D sensor must be increased by less than 10%.

It is also worth mentioning that the measurement errors of the points, presented on the graph below, ranged from 0.4 to 1.2 lpmm.

Pentax smc FA 35 mm f/2 AL - Image resolution

When you look at the performance in the frame centre there’s almost nothing to complain about. Even at the maximum relative aperture the results are useful - at the level of 30 lpmm. The Nikkor seems to fare a tiny bit better there but by f/2.8 and f/4.0 it is worse so we can announce a draw with a clear conscience. Especially that the differences were so small that most of them could stem from measurement errors. The weakest performance here presents the Canon which, at the maximum relative aperture, even after scaling by these 10%, reaches merely 25 lpmm and also by f/2.8 it lags behind the rest.

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When we get to the frame edge performance the situation becomes a bit more complicated. Maximum aperture seems to be the Pentax’s domain. Here, the frame edge results differ just slightly from those in the frame centre which is praise-worthy in itself as the results are also significantly higher than those of the rest of competitors. By f/2.8 and f/4.0 the Pentax still prevails over the Canon and the Nikkor but on further stopping down it can’t reach its rivals’ level. The increasing chromatic aberration is partially the reason but we are going to deal with it in more detail in the next chapter.

If we want to be honest, though, we must stress here that the MTF50 values reaching 30-35 lpmm, like those of the Pentax at the frame edge, are good and allow to generate sharp photos. Perhaps those photos won’t be outstandingly sharp but they will be sharp enough for most uses.

To sum up the resolution of the Pentax 2/35 didn’t make us worry at practically any moment and in this category the lens deserves to be praised. At the end, traditionally, we present our test chart crops which we got by saving JPEG files along with RAW files.

Pentax smc FA 35 mm f/2 AL - Image resolution