Can anyone explain how the NR settings is affected, according to Camera Setting?
There are (at least) two components of noise reduction:
1 Noise reduction on the sensor raw data +
2 noise reduction SETTINGS (besides the sensor raw data)
in the raw files which keep information for DPP etc.
What I deduced from my cameras (40D, S95):
Long exposure noise reduction exposures a dark frame (shutter closed) with the
same exposure time as the image exposure (e.g. 15 sec exp time means 30 sec
for one exposure process!). The dark frame image is subtracted from
the image frame to remove noise, especially hot pixels (which show signals without
getting light). This affects the sensor raw data.
Noise reduction settings are stored according to the chosen ISO (and exposure time?)
in the "settings section" of the raw file. These do not affect the sensor raw data but
the development in DPP (etc.).
I haven't found a menu setting to suppress the noise reduction settings for DPP
in my camera.
Edit one image to set the noise reduction to zero (NR is usually
applied at base ISO and degrades percepted sharpness!).
Copy the recipe to the other images of that series.
Best - Michael