Most likely:
What you see here is the Max Sample Intensity being re-evaluated when the scene is re-rendered with different exposure. See here for more information:
https://support.chaos.com/hc/en-us/articles/4528507399441This means that most likely your scene is incorrectly lit with mostly indirect light instead of direct illumination, or that you are using self-illumination instead of light materials / Corona lights. More information on using self-illumination vs lights:
https://support.chaos.com/hc/en-us/articles/4528322665745The solutions would be either:
- Reworking the scene to be lit mainly by direct lights
or
- Going to Render Setup > Performance and setting Max Sample intensity to a higher value (e.g. 1000 - but this will introduce more noise to the rendering) or setting it to 0 (this will disable MSI and will introduce A LOT of noise to your scene)
It is also a good practice to set light intensity and camera exposure first, then render, and then adjust the exposure in the VFB as the last post-rendering step.
Another thing you can try is going to Render Setup > Performance and changing the secondary GI solver (at the top of the window) from UHD Cache to 4K Cache. It is more physically accurate, so this effect should be generally weaker when using it.
This is not something new, it is the same in Corona 7 and any older version.
