I'm trying to learn the difference between how MODO renders glass and how Octane does. Since Octane has a dedicated specular material, it seems to work differently. For instance, glass has relatively low direct reflectivity, but high fresnel reflectivity. So in MODO I might start off with 10% reflection and 90% fresnel, with 100% transparency, 1.55 IOR, and no diffuse color.
However in Octane, there's no separate fresnel or diffuse control (which is probably more physically accurate), just specularity and index. But a low specular value just makes the glass look dark. Why is that? I need to turn up specularity to 0.8-1.0 for it to look right. Of course, I get white fireflies all over with it set to 1.0, but it looks better there. Also, Octane's transmission color seems much more sensitive than MODO's transparent color control, which basically provides the equivalent function.
So, I guess I'm basically looking for help understanding how this specular model works, so that I know why I'm getting different results.