For some reason I can't get it to work, increasing distance dims the render, the background models are still always brigther than the sky.
How does one go about doing a plausible Rayleigh scattering atmosphere with the VolumeMTl? what values should I use? I saw no guide on how to do that.
I think in real life fog is usually layered, which means that it ends at some height so sun rays may travel freely until they hit fog*. In Corona, fog works based on distance. So basically imagine a huge volume filled with scattering media (example: smoke, volcano explosion) - it is bound to make the scene very dark. I would advise you to try some of the following:
-adjust enviro distance and fog material parameters
-change fog directionality to about 0,9 and see what happens (should create nice halo around sun)
-instead of using global fog, use a huge box with fog material, the reason is that it can end at a defined height - just remember not to put your camera inside it
*before someone smart starts talking about atmosphere - this is just a simplification ;)
In attachment is my example of fog, with default enviro distance setting.