It has 12 stops of dynamic range but I wondered if anyone accurately knew how this was distributed? Normally it's more stops to the shadows than the highlights
Basically, there is roughly 3 stops of DR above the metered 18% mid-tone. That would imply roughly 8 stops below it. The lowest few stops will be terribly noisy.
But the 18% grey card/light meter thing is only a guide in MFD, since it depends on how faithfully the manufacturers adhere to the saturation definition of base ISO (they tend to "overdeclare" it, which gives more highlights headroom than you'd expect; perhaps because they think that this is what photographers want; that or the faster shutter speeds indicated by a higher ISO). And since a source of illumination, or a scene area under stronger illumination than your surroundings, can saturate (and even worse, bloom into adjacent pixels in the same column), even when you meter everything else in the scene on the basis of its reflectivity or use a reflective grey card, you are not guaranteed success with that type of metering. As Torger and Yair suggest, doing it by the histogram is a better way to maximise signal to noise without either saturating or underexposing unnecessarily.
Ray
