Shadows: how can shadows be reduced without reducing the light intensity or softening them? I don’t see any way to control whether I have a solid black shadow or just a percentage - I don’t want my shadows to look like a flashbulb went off, at the same time I don’t want to underlight my subject.
What I usually do is set up a light to provide the level of illumination I want in the shadows, with Shadow type set to None, then create a new light of the same type and expand the dialogue to show more options, from which I select Copy selected light. Adjust the intensity of the new light, set Shadow type to be one of the active options, parent one light to the other for easier adjusting. The uber lights (point and spot) do allow the adjustment of shadow intensity but they are paid-for add-ons.
Addl. parameters: what are “Display persistance,” “Ray Length” and “Ray Opacity, ” “Edges” and “Edge Opacity?” I get the feeling these latter are something relating to atmosphere?
These are the properties of the guides emanating from the light avatar - so you can make them more visible as required.
What are the “Diffuse” and “Specular” choices under “Illumination?”
These control how the light affects surfaces - Diffuse gives light, but no specular highlights, while specular doesn’t light the surfaces it falls on at all but does give specular highlights. The former can be useful for a fill light - I often use a low intensity light set to Diffuse only parented to the camera - while the latter can be used to add interest to shiny objects without over-lighting the scene (and can be very useful with environment lights, which tend not to give good specularity).