D200 NEF Files Can Be Affected by Noise Reduction
Prepared 2008-03-07 (149/117846) by Bill Claff
I had previously researched this for the D70 but never
published those results.
Due to some renewed debate on the subject for the D300 and D3; I retested the D300 and D200.
(I no longer have the D70 and expect D3 results with the assistance of a collaborator.)
The test procedure is quite simple.
I took a pair of "lens cap" shots at every shutter speed at the lowest ISO setting.
With all noise reduction turned off.
The expectation would be that the noise would be level or rise slightly with longer exposures due to Dark Current.
(FWIW, the test shots were taken in order of longest to shortest duration.)
However, with both cameras there is an abrupt drop in the noise (and signal) at a particular shutter speed.
(I'm certain this will be true for the D3 as well, I simply don't have complete data yet. When I do I'll post in that forum.)
For the D200 the threshold is 1s and for the D300 it is 1/4s.
Here are charts of the results showing noise (signal is quite similar):