Originally posted by Adam The k3 has more noise, that should help explain it.
Adam,
In IR's own write-up, the K-3 does worse with the red cloth than the NEX 7 and the D7100, which have similar sensors, so I don't think that it is simply a matter of more noise. The editors pointedly comment on Pentax's history of poor rendering of detail in reds.
I have done some more experimenting with my raw convertor, and I believe that the problem lies with the color noise reduction. Noise Ninja 4 (inside Photo Ninja) has the default color NR set at a value of 50. If I set it to 0, some detail in the cloth is restored, along with tons of chroma noise. If I set it to 18, I lose more detail,and almost all of the chroma noise vanishes. ACR seems to handle the red chroma noise a bit better. This is one of the few cases in which ACR outperforms Photo Ninja, although I have not seen the same advantage with my K-5 or K-5II.
Below are the IR samples from Photo Ninja/Noise Ninja 4 with color noise at 0 and 18.
Edit: I forgot that luminance NR was turned off in ACR. If I add luminance NR equal to that in Noise Ninja, there is only minimal difference in the red cloth and less detail everywhere else. On balance, Photo Ninja/Noise Ninja is definitely superior.
Rob