thw2 wrote:
Without ACR's dabbling (i.e., when EXIF ISO values are edited to appear as 100), the noise characteristics look grainy and pleasant looking. This is why ACR treated high ISO images always appear soft even when NR settings for both luminance and color are reduced to zero.
This series of photos is akin to comparing ACR against DPP, all with NR = 0.
A 'neutral' program like DCRAW is probably more suitable when comparing camera RAW output.
I wonder if it is really NR at play here, or whether ACR is instead toning down its internal sharpening algorithm for the high ISO files, in order not to amplify the noise footprint? I'm just speculating, because I haven't done the testing others have done, but from the comparison posted it seems like different sharpening might explain the results too?
In either case, it's useful information to be aware of.