How to "properly" use: Specular, Glossy, Roughness & Reflection maps

[pixelgrip]

A specular map usally contains F0 reflection data (based on PBR Guide).In the principled shader,the data are artistic IOR values.With the formula Mario posted ,you can put IOR values direct.

Dont be confused,but F0 reflection data are in short,the resulting reflection amout of the Fresnel formula.
These are not IOR values and not principled specular values.

However,I have made a specular (F0) to principled specular input converting node group,based on a PBR guide.
here the link

How would you use specular maps now based on what he said?

Small update,i made a mistake with the last noodle screenshot.The black value is not from the spec map,instead its from the Diffuse color map. Based on Allegorithmic PBR Guide [workflow1] as you can see,the black parts on the diffuse are these parts that gets metallic. Since in the specular workflow (all based of the PBR Guide),the Metallic color are taken from the spec map,i simply added the color from the spec map to the diffuse map,if the diffuse color is pure black(0,0,0) [f0converter…