I've made 11 pictures of a Voyage and an Oasis 2 in a dark room at brightness levels 0, 1, 2, 3, 6, 9, 12, 15, 18, 21, and 24.
The Voyage is from a few weeks after initial release and it is running firmware 5.6.1 which is neither the initial nor the current version. I am not yet aware of Voyage firmware affecting screen brightness or light distribution. It may be that newer Voyage hardware has less blue in the front light, so these images may be most useful for owners of older Voyages considering an Oasis 2.
The Oasis 2 is from release day. It was immediately put in airplane mode and has not been updated from the initial firmware version 5.9.0.6
Post #19 in this thread shows the 5 darkest settings for the Oasis 2 in inverted black and white mode next to a Voyage set at brightness 3.
Post #41 in this thread has a video of the Oasis 2 flashing in inverted black and white mode.
Code:
File name Exposure Time F-Number
voyage_oasis_dark_b00.jpg 1 sec. f/2.8
voyage_oasis_dark_b01.jpg 1 sec. f/2.8
voyage_oasis_dark_b02.jpg 1 sec. f/2.8
voyage_oasis_dark_b03.jpg 1 sec. f/2.8