Lights and modifiers
Select a light to see its controls at the top of the Inspector. The heading tells you what it is: Continuous Light or Flash Light. The switch turns it on or off, and Solo shows that light on its own so you can judge what it does. This article is about continuous lights; flash heads have their own controls, explained in Flash, TTL and HSS.
Strength works in stops, from full output (1/1) down to 12 stops less, in tenth-stop steps, like the dimmer on a real light. All the way down switches the light off. That makes lights easy to compare and match.
Lamp power picks the class of light source, in watts. It describes the size of the lamp, not what it draws from the wall.
The Light tab
Temperature sets the color of a continuous light, from a warm 2700 K to a cool 10000 K. A flash has no Temperature: it is fixed at 5600 K and changes color only with a gel. Spot lights also have Beam for the width of the beam, and some lights take a Gel for colored light.
These are generic lights based on real reference measurements. They are a good guide for planning, not an exact copy of one brand.
The Modifier tab
Choose the Modifier family, Size and Variant, for example a softbox, umbrella, octabox or beauty dish, and add a Grid where it fits. A larger modifier gives softer light, and every modifier costs some light, as in real life. A flash only offers the modifiers that exist for flash.
A projection spot also has Projection: choose a Pattern such as Window, Blinds or Circle, and set its rotation, size and focus distance.
The Aim tab
Aim at picks the model a light points at, and Aim now turns it there. With Follow model on, the light keeps facing that model when either one moves. Changing pan or tilt yourself turns following off.
Light guide switches the line that marks where the selected light points on or off.
Equipment joints turns the light head (Head pan, Head tilt) and raises the stand (Stand extension). Light measurements shows the height, the distance to the face, the side of the face and the height above the head. Left and right are seen from the model.
Light Info and Pattern
Switch Light Info on at the bottom of the 3D view to keep the details of the selected light in sight while you work. When a model is selected, the Pattern tab names the light pattern on the face, such as Rembrandt or loop, so you can check your setup at a glance.