Hi, Robo. Specular lights are easy really. Just go into the material room, select the light you want to be specular only, and do one of two things: Either make the diffuse color for that light 100% black (it's usually white by default), or press the "Set Up Light Style" wacro button to the right of your mat room panel (under Wacros), and choose "specular only" as the light style. For the diffuse IBL light, there's really no need to mess with Angle Start/End, since the IBL covers your entire scene 360 degrees all around. Angle Start/End is used for spotlights, and adjusts the angle of the "light cone" that they emit. I don't think the angle on spots ever actually exceeds 180 degrees, even though you can put any integer you want there.

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Tools :  3dsmax 2015, Daz Studio 4.6, PoserPro 2012, Blender v2.74

System: Pentium QuadCore i7, under Win 8, GeForce GTX 780 / 2GB GPU.