background through refractive mat too dark

[re:FORM]

If I have a clear material, and if I don't tick 'affect background' the refractive material still shows the background as though it has been affected by exposure/colour-mapping. When I switch on 'affect background' the transparency matches the background (ie thebackground is now darker to match what the transparency was showing). I want the background to be exposed without colour mapping and for the refraction to refract the background at that exposure level.

Is there any way for a transparent material to show the correct brightness of the background?

an image to help explain my jumbled explanations

[RErender]

yep, that's to be expected. best to make your background brighter and color map it.