A key point lost on those who treat \"shadow pushing\" as some marginal or outlier exercise is that High ISO is the exact same thing - post-capture gain applied to an image so that it has adequate output brightness. The only difference is that most CMOS sensors produce a better image if that gain is applied in the analog domain rather than digital. This applies to all Canon CMOS sensors and all non-Exmor Nikon sensors, such as those in the D3/D700/D3s. With the advent of the Sony Exmor sensor the difference in post-gain IQ between analog and digital gain becomes very small, to the point of almost being interchangeable on the D800. This is what facilitates the concept of \"ISOless\" shooting, where instead of having to shoot at a specific High ISO for acceptable IQ you can instead shoot at a low ISO and arbitrarily push the exposure digitally in post with nearly the same IQ, with the added benefit of maintaining the base ISO dynamic range since analog gain results in 1 stop loss of DR per ISO step.
Would anyone then claim that High ISO shooting is a marginal or outlier exercise?
Here\'s an example... a D800 image shot at ISO 100 but in lighting conditions roughly equivalent to ISO 3200. The exposure was pushed in ACR, allowing the full retention of ISO 100 dynamic range (note the TV screen) but without any IQ penalty associated with traditional sensors
