I'm using the most recent version of the LucAdapters Magic Booster specifically designed for the URSA 12K. It effectively turns this camera into a 'cheap' ALEXA 65, adds a stop of light and flares more organically and preserves contrast more compared to the previous generation. You can also get away with opening the iris to about f1.8 and still maintain sharpness. Video was made entirely with available light which definitely shows how great the URSA 12K is at recreating what your eye sees.

Lenses:
Sigma ART 24-70mm
Helios 50mm

Primary colour in AutoKroma. Secondaries in Film Convert.