Does anybody know how to change the aspect ratio in-camera? I recognize that we are "forced" into 2.39:1 in order to achieve high frame rates, but I'd like to be able to shoot a project natively at 2.39:1. DJI's spec sheet implies this is possible and has even published bitrate data associated with that aspect ratio at various resolutions. Any ideas here, outside of dealing with it in post?

Do you use anamorphic lenses?

I do not, but most cinema cameras (DJI even suggested it for this camera) have the ability to change the aspect ratio as a menu selection.

I am looking at the same as above, i am shooting and i get forced anything above 30fps at 4k into (2.39) 4096x1716 when the website states it can do up to 120fps i only get a max of 50fps?

CFexpress 2.0 Type B Recording Format [5]
ProRes 422 HQ/LT:
6K: 23.976/24/25/29.97/30fps
C4K: 23.976/24/25/29.97/30/48/50/59.94/60/72/96/100/120fps
2K: 23.976/24/25/29.97/30/48/50/59.94/60/72/96/100/120fps

Shoot in 4K with Frame Guide set to 2,39:1 is one way to do it, of course it'll still be 4K and not 4096x1716 - but the Frame Guide Transparency % can help with the output on your 4D monitor.