What is the equivalent of Spec Power?

I was testing out a mesh and it doesn’t give the right appearance without spec power, so I was wondering what would need to be adjusted to compensate for this.

Specular is actually like specular power, since its linear colours it can go well above normal visible ranges so if you want to make it brighter/darker you just multiply your specular with white/back. Or are you using roughness/metallicness?

That is controlled by the lights now. Each light applies a different type of spec power to a surface. The Source Radius and Source Length properties in lights set this, so you can now also shape the spec reflections into something other than points using this.

Roughness is actually a lot more like the old specular power node in UE3! (In that it controls the Size of the specular lobe)

I’d advise you not to touch the specular input for the most part- 90% of the time you don’t need it.

You really need to study what Physically Based Lighting\Shading is. Then all the questions regarding the basic material inputs and their interaction with light will go away. Here’s a start:
In short, you do not have the direct control over the Specular Power anymore (the size of the spec. highlight as it was in UE3), now it is all dependent on the roughness, and the brightness of the highlight also changes without your intervention in an energy conserving manner (you don’t need to adjust the specular brightness manually). The fresnel now is also not something you should try and impose in your shader manually. It changes in accordance with your surface being metal or non-metal and the value of the albedo\diffuse.
In simpler terms - much less eyeballing and manual shader twitching is required but good PBS understanding is a must.

What about the equivalent to Transmission Masks and Transmission Color?

See Subsurface.

Thank you.

(128-SPW)/128= Roughness, or SPW/128= Roughness

For maps:
Unreal engine 3.x: SPW = ((SPWmap*19)-1)^2

Unreal engine 3 : ((SPWmap)^2)*500

Specular: Greyscale only, default 0.5

Specular = ((ND-1)^2)/((ND+1)^2)