I have to say now I'm completely confused about the workings of portal lights.
I've been testing some interiors renderings with Mantra, and constantly getting strange results. It seems the portal lights were the problem. I have setup and uploaded a simple scene to show how I'm configuring them and to try to understand why I'm getting the opposite results to what's expected: more noise /worse sampling with the portal lights on for exactly the same rendering settings.
Worse quality picture is with Portals on. I attach the scene file, hope you can help me, I'm sure this is a very trivial issue but I'm not seeing what's wrong…
Thanks in advance!