This command opens the Add Default Lights To Scene dialog, which provides options that let you convert the default scene lighting into actual light objects.
The default lighting for viewports consists of a key light, positioned in front and to the left of the scene, plus a fill light behind.
This command is available only when the Viewport Configuration dialog is configured to use two default lights. If that's the case, when you invoke this command the lights are added to the scene as omni lights. You can opt to add the key light, the fill light, or both. The light objects have the names DefaultKeyLight and DefaultFillLight
Two default lights are placed opposite to each other: A. the key light, is in front of the object on the upper-left side, while B., the fill light, is behind on the lower-right side.
If you have already added one or both default lights, a warning prompts you to rename or delete the previous default light object before you add another.
To add the default lights as objects:
The lights are now visible in the viewport.
When on, adds the default key light to the scene. The key light is in front of the scene and to the left. The key light becomes an omni light with the name, DefaultKeyLight. Default=on.
When on, adds the default fill light to the scene. The fill light is behind the scene and to the right. The fill light becomes an omni light with the name, DefaultFillLight. Default=on.
Affects how far the lights are placed from the origin (0,0,0). The default value leaves the scene's lighting unchanged. Larger values move the lights farther away, dimming the scene, and smaller values move them closer, brightening the scene. Default=1.0. Range=0.0 to 1000.0.