Camera-gear YouTuber Kobie M-C tested the K-3 and K-3 III side by side and here is his report:
https://www.youtube.com/watch?v=pH2eQD6fpA0
And, his quick textual comment follows, quoted:
"Some interesting things occurred during the shooting for this test. It seems the K-3 Mark III sensor out resolves some lenses including the DA 50 1.8 which surprised me. It's a good lens, nice and sharp, but just not on the K-3 Mark III. I tried live view, electronic shutter, Focus fine adjustments from -10 to +10 and it was still soft. F/1.8, 2.8, 4 (when the lens is sharpest) and still the same result. This might be what some professional reviewers are experiencing when they mention soft images."
The below quick snapshot refers for easy reference:
(Click to Enlarge)
As the increase in the total number of pixels of the K-3 III against the K-3 and KP is really marginal, I think there exists another factor to cause the decrease in resolution in image corners for images produced by the K-3 III, even for the same old lenses, which used to be optically good.
I suspect the (different) design of the micro-lenses and (different) assumed incident angle of light should come into play. Indeed, the
new 26MP Sony sensor was first used in the
Fujifilm X-T4 which has a much short
back focal distance. Later on, Ricoh got this sensor and put it into the K-3 III. However, the new sensor is not that highly compatible with many of the old glass in optical sense, especially at the image corners and edges, and that wide angle lenses suffer more than standard and tele ones.
I have verified this with the latest glass marketed by Pentax, in particular, like the D-FA* 16-50 PLM, which shows a much lesser problem for the aforesaid issue and phenomenon.
Related Article:
When the Sensor Outresolves the Lens
