[richardfollett]

I read somewhere that the multilight function is not just limited to emitters and that it can also be used with image based environments.. and that you can change the HDR after render has finished to create whole new image, is this the case, if so how does one do it?

Thank you

[JDHill]

The first assertion is correct; you can adjust the intensity of the image-based lighting via multilight. The second is not; you cannot change the map used to light the scene. To do so would be to invalidate whatever calculation (i.e. the rendered image) had been done up to that point, since it would amount to changing the position of light sources, and would therefore require different physical paths to be calculated.