Sony FX 6 Quick Start Manual page 51

Custom Shooting Mode: Main Settings
Scene File/ S-Cinetone. This is the best choice! More about this later.
Shutter: always set to twice the frame rate: 1/48 for 23.98p and 1/60
for 29.97p.
The ECS shutter speeds are for eliminating rolling lines when shooting
monitors, screens and projections.
Base ISO/ Sensitivity: there are two choices, Low or High
When shooting in Custom mode: the Low Base setting is: 320 ISO and
the High Base setting is 5000 ISO. The higher ISO number is more
sensitive to light. See next page for detail.