Hi guys,

I´d like to understand the relationship between the attribute "Cm 2 Factor" inside mia_photographic_exposure and the intensity of a Portal Light as a direct light (without Physical Sun and Sky).

I have a scene that simulates a studio. There are some big objects and a curved background. The scene scale is 1 unit = 1 centimeter (0.39 inch).

For illumination, I put an area light with "Use Light Shape" and "Visible" on, and I plugged the mia_portal_light in Light Shader. To Portal Light works as an emitter light, I turned off "Lookup Using FG Rays" and turned on "Visible" and "Use Custom Environment", keeping this blank. Ok.

If I keep "Cm 2 Factor" = 1, the intensity of portal light must be something around 10000 (Obs: I set other values of exposure, as camera sutter, Film ISO and F Number).

If I change the Cm 2 Factor value to 1500, the Portal Light intensity works fine with 30.

What is the correct workflow? Keeping the Cm 2 Factor with default value or not?

Thanks,