does it work like this in Max? We didn’t write the IES light code at all, that’s all Chaos Group. If the light works the same as it does in Max, then there is no bug. If the light works differently, then if we can figure out what we need to adjust to make it work properly we will. There was an issue in the past where IES lights were entirely too dark, but that was due to a units issue. We fixed that issue, and now they should be working the same way they do in V-Ray for 3D Studio Max. We were told that the light was functioning as it does in Max, but if anyone would like to point out any differences between the way the two lights function, I would be willing to see if there’s anything that we can do about it.
As I said before the physical camera reduce the exposure of the IES lights and the IES light power is in lumen. A typical 100W electric bulb emits about 1500 lumens of light. So if you use the physical camera you have to use a very very very high IES light power. If you don’t use the Physical Camera, then it is what Devin said, with the default IES power data sould be enough.
When I said that you have to use the physical camera to control the exposure of the scene. I was not referring that you control the brighter of the lights (multiplier or power) with the camera, so the value that you use for the camera are crazy values ;). You should use the Physical Camera to control the exposure of the sun and the lights multiplier or in the case of IES, the power, to control the exposure of the lights. Again the Physical Camera reduce the brightness of all the lights type even IES lights. This is the way how work in Max too.