The above example is a quick example of using a simple object, like a sphere, a cube or a cylinder, and render it first to work out the primary and secondary light sources. Then use that quick “study” to inform how to light a scene. This is obviously not a full scene, but I’m showing how working out the problem on the sphere helped me to visualize the light source first, that I could then apply to the planes of the head.
It’s not perfect, and if I were to work on this particular painting more, I would get more and more refined, thinking about the shapes of the cast shadows, the reflected lights, the ambient occlusion, etc. working my way into finer and finer detail. At each stage I can refer back to the model of the sphere to make sure I’m using the right general value based on the light source. Even the sphere itself is somewhat roughly done, but even at this level, it proves useful, best of all it’s a quick study, only taking a few minutes to get it set up.
It’s a tool I learned from the Schoolism Course Fundamentals of Lighting with Sam Neilson. They have number of great video courses by well establish entertainment industry artists, one of my personal favorite places to pick up a little knowledge.