One thing that has been brought up is a key issue- cameras in the digital world are electronic beasts, with different sensors and electronic designs. Things were test-simpler in the film era, for more true results. I have noticed a trend among Pentax DSLR bodies being tested by various labs. That is a consistently-mentioned characteristic of the native sharpness before any is added, being more conservative (lower) with the Pentax than with other brands. That is, more post process being needed. Such is the reason OpticalLimits warns about comparing the same lens between systems.
Also notice, as to actual lines measured, upon looking at the same lens results within the Pentax system, take a look at the numbers of lines with the same lens on the K10D vs the 16mp K-5 and you will see a major difference.
But as to JPEGs out of the camera, Pentax has more in-camera adjustability for the setup- the Custom Image menus to set up sharpening, contrast, color palette, etc.
---------- Post added 03-30-20 at 03:33 PM ----------
Originally posted by Kunzite See ephotozine's latest Pentax reviews, those for which they're giving numbers rather than "excellent/good/etc" - no lens will get close to 3500lw/ph.
Yet Nikon's best lenses can approach 4000lw/ph, on a D810. Even a zoom like the 70-300 will reach 3500 (@f11)...
Does the above shed light on this issue?
Now getting down to the ephotozine's reviews of the two lenses in question. Taking into consideration of being tested on two different camera systems, it is best to ignore actual lines-count differences, and just look at how well the lens does. Even with the different systems, a rational evaluation emerges. RE: the 50mm f/1.4 comparison.
I am seeing the Tokina Opera version reaches a very high standard of excellence at f/2.8 on the Nkon camera in the central area. The Pentax DFA* version is still excellent in the central area, though not reaching as high in lines-count on the Pentax camera. However, within its own system, edge performance from f/1.4 through f/4 is in the excellent range as is the central area! Not so with the Tokina Opera on the Nikon system. The most difficult to accomplish for lens design in a 50mm f/1.4 lens has always been to achieve sharpness at large apertures, including wide open. Amazingly, the Pentax DFA* accomplishes this beyond any expectation! Razor sharp at f/1.4!! Edge-to-edge sharpness!
The two lenses appear to be of similar performance at f/5.6, with the Tokina Opera a bit better at smaller apertures, which is easier to accomplish, so I would take that trade-off to get the near-impossible delivered by the Pentax DFA*! No question as to which one I would buy!
As to CAs, although the Tokina Opera on the Nikon camera shows better than the Pentax DFA*, what does that matter when both lenses are well within the excellent performance range as stated by the review?
As to the DFA 70-210mm f/4 lens, it is quite common for even top-notch zoom lenses to dip somewhat in quality level at the longest FL setting. Sometimes, even this is improved quite a bit by zooming just short of the longest FL- in this case zoom just to 200mm to see if performance comes up to excellent again- or at least very good.
I have no interest in either of these two lenses for my own usage, but these would be my observations in terms of making recommendations.