Environment light strength not affected by camera's exposure settings

[Alex_M]

I'm not sure if this is a bug or by design but if I use the "GI environment" in the "Environment" tab for lighting my scene, changing the camera settings such as ISO or exposure time doesn't affect the exposure of the scene. Same happens if I use a texture or color in Max'es environment slot. "Use per-camera exposure" was active in my tests and the camera had installed exposure control. If this is not a bug, how do I increase the strength of my environment light?

I made a video that you can download here (15mb): https://we.tl/cx5eVHyKq7

[Zdravko.Keremidchiev]

Keep in mind that the range of values that you are testing for Duration in seconds and ISO won't produce very different brightness difference. Instead try something like 0.01 sec compare to 10 in example. the difference in the lightning when you have the shutter opened for 500s and 900 will be so great. But if you open the shutter for very short time the brightness will diminished. Also I will advise you to use Aperture to control the exposure. The duration is usually utilized for MB effects.

[Alex_M]

Thanks but what if I want to change the environment light strength without changing camera parameters? In my particular case it's very important that the camera parameters don't change, just the lights. For example, in the current interior scene, increasing the "Overall mult/Render mult" values in the HDRI map between 0 and 10 have effect but anything above 10 has absolutely no effect on the strength of the light coming from the HDRI map. I tried a value of 9999999 and the HDRI is still as strong as it was at 10. Why is that? I want stronger HDRI environemnt light without changing camera parameters. How do I do that?

PS: I found what the problem was! I'm using Vray Lights in Portal mode but with "Simple" option disabled. As soon as I enabled "Simple", all changes to the strength of the environment have effect and I can light my scene properly! Is this normal?

[svetlozar.draganov]

PS: I found what the problem was! I'm using Vray Lights in Portal mode but with "Simple" option disabled. As soon as I enabled "Simple", all changes to the strength of the environment have effect and I can light my scene properly! Is this normal?

It depends from the scene setup. Is there any geometry that could block the light(partially or completely) from the environment to reach the portal light?

[Alex_M]

Yes, I think there were some planes with VrayLight materials used for background.

[svetlozar.draganov]

If you remove those while keeping Simple Portal un-checked does the illumination changes when changing Overall/Render multiplies of the HDR-texture plugged in the Environment slot?

[Alex_M]

No, illumination didn't change when I removed the planes and un-checked "Simple". It only changes if I check Simple (regardless if there are BG planes behind or not).

[svetlozar.draganov]

That's a bit strange, if nothing block the light behind the portals it is not supposed to have discrepancies between enabled/disabled Simple option unless if there is a bug.
Would it be possible to send that scene for investigation?

[Alex_M]

Yes, sorry for the late reply, I've been a bit busy lately. I just sent the scene to support.