Rather than use dark noise as a stimulus as in the preceding post, I have made a series of measurements of the histograms of the Nikon D4 and D800E, and the Sony RX-1 and NEX-7 when presented with a featureless surface eight or nine stops below clipping. I did not include the Leica M9 because… [Read More]

I started a thread on Luminous Landscape about computing unity gain ISO from a single exposure, and it’s gotten pretty interesting. There have been useful discussions about what good knowing the Unity Gain ISO is in picture-making. One of the discussion led me to make some test images and look closely at their histograms. In… [Read More]

There’s enough data in the test exposure that I talked about at the beginning of this series to calculate the full-well capacity of the photosites in each camera, if we make the reasonable assumption that the manufacturers of the cameras set the gain of the amplifier at base ISO so that the ADC clips at… [Read More]

As you might expect, there is a strong correlation between Unity Gain ISO and pixel pitch. The Leica M9, the only CCD (and, I think, the only non-Sony) sensor in the bunch , is an outlier.

A Nikon D800E produces these results at a count of around 500: The Sony RX-1 at a count of around 4000 looks like this: And at a count of 500, it’s a little different: The Leica M9 at Zone VI has a pronounced hump: The Sony NEX-7 had anomalous behavior at ISO 6400: We saw… [Read More]