Camera · Framing
Shoot 16:9, frame for 2.39 — you keep the extra image to reposition in the edit.
Frame for a 2.39:1 film on a 16:9 iPhone recording UHD (3840×2160). How many vertical pixels do you keep?
Assumptions: the delivery frame is centered and keeps the full width (letterbox) or full height (pillarbox) of the recording, rounded to the nearest pixel. Safe areas follow the modern 93% action / 90% title convention. Some cameras crop the sensor for 4K or stabilization, so "recorded frame" means the file, not always the whole sensor.