Best lenses for the 24-MPix Pentax K-3: Recommended primes and zoomsBy Kevin Carter - Monday January 06 2014 Lens Recommendations
Although a full-frame lens and the equivalent to a 50mm on the Pentax-K-3, the Sigma 35mm f/1.4 DG HSM A is the best performing prime overall in our database (on the K-3). It’s a big heavy lens on the Pentax-K-3 but the build and image quality is very high. Peak sharpness is measured at 16P-Mpix, 3P-Mpix higher than the next measured model (the DA Limited 35mm f2.8 Macro –either the new HD model or earlier smc version).
With the same DxOMark score of 27 points and technically occupying joint first place, albeit with a lower peak sharpness score is the Pentax smc DA* 55mm f1.4 SDM. As the equivalent to a 85mm on the K-3 it’s well corrected optically, and an excellent performer, though at $249 the more modestly priced APS-C only DA 50mm f1.8 isn’t quite as good a performer though with marginally higher peak sharpness it may appear to skew the ranking slightly when measured on the Pentax K-3.
Although we’ve not had the opportunity to analyze either the 16-Mpix K-5 II or the K-5 IIs (sans OLPF), we can compare the K-3 with the earlier K-5 (from 2010), which had related sensor. Although the overall pixel count increased 50% from 16.3-Mpix to 24.3-Mpix, the linear increase is much lower at around 22% - however, bearing in mind the Pentax K-3 has no OLPF increases in sharpness should be significant, especially with the right lenses.