Hello, since the principled shader is going to be released in 2.79, I’ve made a node group to translate IOR values to specular value. It’s just a translation of the formula into nodes (from https://docs.blender.org/manual/de/dev/render/cycles/nodes/types/shaders/principled.html )
The node group can be attached from this file
http://pasteall.org/blend/index.php?id=47769
THANK YOU!
I was trying to do the same thing but I’ve seen yours. Perfect.
:D:eyebrowlift: