Yesterday we saw that the Leica M240 is “ISO-less” five stops from full scale — moderate shadows in a normal outdoor scene. Today, I repeated yesterday’s testing, but two stops from full scale — the brighter parts of a normal outdoor scene, but short of the highlights. Actually, the blue channel is two stops from full scale. The red channel is slightly lower, and the two green channels are slightly higher.
Here are the SNR results with varying ISO setttings:
And here’s what you get when you subtract out the half-stop-per-stop photon noise contribution to the SNR.
We see a slight improvement in corrected SNR at the higher ISOs, indicating that, if you can’t shoot at base ISO, you’re slightly better off in the brighter parts of the scene increasing the ISO setting in the camera that underexposing and pushing in post. But, remember from yesterday that you’re worse off in the shadows, at least at ISO 3200.