RED ONE OPERATION GUIDE User Manual

Page 153

Build 31 v31.6.16

NOVEMBER 28, 2011

152

ISO 100 - no exposure adjustment

In these extreme examples it is clear that the RGB domain images are respectively very bright and very

dark. The histogram data reflects that, however you can also see that the sensor RAW meters are un-

changed. The exposure at the sensor at this point in time is the same. If you choose to close the iris to

reduce the brightness of the first image you will be reducing exposure at the sensor – this biases expo-

sure in favor of protecting the scene highlight. Alternatively if you choose to open the iris to increase the

brightness of the image of the second image you will be increasing exposure at the sensor – this biases

exposure in favor of minimizing noise in the scene shadows.
The technique is similar in principle to re-rating a film stock. With practice the ISO rating can be used as a

tool to assist ideal exposure based on the dynamic range identified within the scene.