Can the full exposure latitude of ALEXA be recorded as ProRes onto SxS PRO cards?
The short answer is: yes, the full exposure latitude of the ALEXA can be recorded as ProRes onto SxS cards. The long answer is this: The ALEXA sensor can capture 14 stops of exposure latitude. This image data is processed internally in a 16 bit format. Whenever this data is converted to an output, be it the 12 bit ARRIRAW, 10 bit HD-SDI, 12 bit ProRes 4444 or in any of the other 10 bit ProRes formats, the whole exposure range of the captured image is mapped from the 16 bit range into the respective target output range (see graphic). So while the range from brightest to darkest image content remains the same, what changes is the number of different lightness levels in between. A 12 bit image has more steps between the brightest and the darkest parts than a 10 bit image. If there are not enough steps between the brightest and the darkest part of the image, you will see banding artifacts, where, rather than seeing a gradual change in lightness, you will see distinct bands of lightness. 10
