Hi Stefan,
Exposure controls are currently "partially compatible" with the OCIO based color management. The proper interplay between the existing 3ds Max exposure controls and the OCIO color pipeline is not implemented yet at this "Technology Preview" stage, so as you have discovered you can easily end-up in confusing situations.

In the current implementation there are few different ways to set the overall scene exposure but I think the best and most compatible way with the rest of the system is using the "Physical Camera Exposure control" but making sure that it doesn't apply any non-linear curve. This way physical camera exposure control will only change the linear exposure but the tone mapping and monitor transfer function will be handled by the OCIO on top of that.

To do so you need to dial the "Image control" settings in the "Physical camera exposure control" as follows:

• Highlights: 1.0
• Midtones: 0.4545
• Shadows: 0

The interesting number 0.4545 comes from the fact that in non-gamma modes this exposure control applies hard-coded 2.2 gamma to make the values ready to display, so we have to dial 1/2.2 = 0.4545 to undo that to return to linear world.

With this you should be able to set the "scene referred" overall linear exposure with the various "EV" settings as usual.

Also please note that you can set the viewport exposure values temporarily for diagnostic purposes, those settings won't effect the render output.

Please let me know if this works for you.

/Cuneyt

Cuneyt Ozdas
Principle Software Engineer