I've been messing about with the GoPro Hero8 Black for 2 days getting the settings right for night time under street lights.
First ride at night, I set it to what people recommend for night time under street lights (min 100 ISO, max 800 ISO) and the video came out too dark. It was also at 24 FPS and 1/48 shutter, which is what it needs to be set at for night time but at 24 FPS, car number plates are blurry when they are going past.
For the 2nd night ride, I set it at min & max 6400 ISO and that came out utilizing what little amount of light there was, I can make out clouds in the sky at 9:30 PM, 3 hours after sunset! The problem though was I again had it set to 24 FPS and number plates are blurry when a car is passing. Without movement it's fine, but at 24 FPS, no.
I'm setting it up again at 60 FPS, 1/120th shutter, with min ISO 100 and max ISO 6400 but I have yet to go out testing it at night on those settings. Lets see if it captures moving number plates with the FPS upped by x2.5.
The problem is, if you raise the FPS, the slowest available shutter speed increases. It's hard to find the right balance and takes a lot of testing! Also if you use 4K, you're limited to "Wide" lens (when it has "Super Wide" on it) and stabilization on a medium setting (when it has a higher setting). Cutting back to 2.7K, these limitations aren't there and you can have the widest lens with max stabilization.
For daytime, it's so much easier, just set it all on auto at 4K/60FPS and it should in theory capture every number plate, no matter what. I hardly ever ride in the daytime hence needing something that works at night.
It's asking too much from a camera to expect it to do everything, I mean it would need a far bigger sensor.
I think there's a big gap in the market to be honest. You want a camera as tough as a GoPro, with a far bigger sensor, so you could have it set to 400 ISO or 800 ISO at night under streetlights and get a nice image. Maybe astrophotographers use such cameras but they probably cost a fortune and wouldn't be robust enough (or waterproof) for this sort of usage. I know even they stack images to get better exposures and they have sensors that are far bigger.
The fact that the GoPro has 6400 ISO is what makes it usable to get bright enough night footage.
Here's a clip fro the GoPro, 4K, 6400 ISO, 24 FPS, no streetlights, just my Cree front light... you have to download it to see it properly (playing it on Dropbox limits it to 720p)
https://www.dropbox.com/s/md86kjhtp7kda ... S.mp4?dl=1
We'll always be together, together on electric bikes.