Hi Willie
Hi Willie
I understand what you are saying, and I only have some experience with the M8, and some info. that I am not sure of (would love to be corrected) on the D7000 (IMX701 sensor).
The M8's gain increases up to 2500 shows the noise over lower settings, that can display the noise associated with gain. Plus there's the issue that with some that had vertical lines or uneven exposures between parts of the image, that the fix was actual capacitors in the L or R image side, etc.
re: the D7000 sensor, I think the on-chip IMX701 Prog. Gain Amp. (PGA) is always on up to 800 or 1600. Whether it can or vendor firmware ever has bypassed it, is not likely, since vendors like Pentax who use the same sensor, but not the Nikon expeed, etc. firmware show the same e noise levels. My guess is that the basic gain balance per color channel are needed to some point. But would be curious if anyone had other info. I hope to get a refurb D5100 at some point for my daughter, to replace her broken D40x.
I can understand how a pro raw only (remember a NEF isn't raw sensor data, it has sensor data + expeed info/fixes added) system can use the sensor's optimal base gain for low noise, and then let a full pc do the developing.
But a dslr, or even high-end RF that does JPGS/DNGs, needs to have something with semi-decent images (e.g. the black images of the older CCD Nikons (D100?), that could actually be recovered if shot RAW, aren't likely coming back...) coming out of the camera media. The PGAs gains have been increasing from 24 to 36ish db (from 4 to 6 stops), but consumer expectations of low-noise high iso, plays a part on where a manufacturer will place that gain, and how much, if any, control they can give the user.
Some cameras only amplify the signal at a single gain value inbetween the the sensor and the analog to digital converter. With these cameras it is impossible to increase the electronic gain. Until recently the only cameras with CCD sensors worked this way. Recently SONY has developed a CMOS sensor has a single gain.
In these designs the integer values produced by the ADC are increased to simulate values that would have been obtained if electronic amplification had been used. I was curious if the M8 and M9 use this method. The Phase One digital backs use this design and they produce excellent results. In fact increasing the camera's ISO value only tells the software what multiplication factor to use.
I would be interested in hearing how you would decscribe what happens to the signal inbetween the time it leaves the sensor and the data is finally written to the in-camera raw file. For instance cameras that increase the electronic gain between the sensor and the ADC also amplify the signal and the noise. Or perhaps you can explain how only the signal is amplified without amplifying the noise?