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Saturday, June 12, 2021

Image Corner Blur Issue with K-3 III (Head-to-head Comparison with KP)

Have had my K-3 III for over one month now and tested it with my various DA/FA/DFA lenses (mostly primes) but there is a strange issue discovered.

It is all about the unexplainable corner (or simple off-centre) softness in the images taken with the K-3 III. To illustrate the problem, here we go with the sample set below, with a pair of images taken using my K-3 III and KP with the same lens (which is a HD-DA 40mm Limited), at almost the same time and with the same exposure parameters.

Let's see the 100% centre crops of the pair of images, which are perfect in focus. I captured also the EXIF data on screen for our easy reference (Click pictures to Enlarge):

Then, here are the left side of the images in 100% crops:

And then, here are the right side of the images in 100% crops:

This problem really drives me nuts. I really didn't expect the new flagship camera would produce much lower resolution at off-centre in images than its predecessor model of 2017. It's really much frustrating after all.

It seems that the new sensor of the K-3 III has some kinds of incompatibility with the existing Pentax lens lineup optically, which is a hardware issue but not a software one, I believe. Note that I had already turned off all the lens correction functions as well as the AA filter simulator to rule out the possibility of the issue is being caused by software or other factors.