Sony FX 6 Quick Start Manual page 100

Cine EI is for shooting Slog 3
Cine EI shooting mode is for exclusively shooting Slog 3.
Slog (pronounced "S Log") is Sony's LOG format which has (optimally) 15 stops of
dynamic luminance range, preserving detail in shadows and highlights.
Why shoot in Slog 3?
1. You have a subject that has very bright highlights and dark shadows and you
need details in both of those luminance areas.
2. You want video images that have a more natural, or low contrast look.
3. You want the maximum control over how the image looks in postproduction
and you have the time to spend on this task.
4. You are not shooting in a situation of consistent low light (no highlights at all).
In such a situation, Custom mode using the Standard and ITU 709 Scenes is
preferred.