Originally posted by HoundFrog Why?.
When color sensor can produce moiré / false colors, such is the case with the K1 (given suitable subject), meaning the lens out-resolves pixel pitch, the monochrome sensor remove artifacts and improve details.
On the K3 III , from color to monochrome the difference isn't as significant because the 26Mp color sensor already sample all the detail lenses can give.
Now, removing the color filter array on a K5 16Mpixels camera, you get a lot more details out of the monochrome sensor, plus less and refined noise, but that is the same for the K3 III.
To see the difference in detail between K3III color and K3III mono, you'd need to use a very sharp lens, e.g DA 35 macro, DFA100 macro, and not stop it down further than about f/5.6. At f8 the difference will be washed out already.