What a light actually does to a face

Every lighting decision comes down to three things: where the light is, how big it is, and how far away it is. Everything else — modifiers, brand names, colour temperature — is detail on top of those three.

Where it is

Move a light a few inches and the shadow under the nose moves across the face. That shadow is the single most useful thing on screen: it tells you the direction of the light more accurately than looking at the light does.

How big it is

Big relative to the subject means soft. A window a metre from a face is enormous; the same window from across the room is small. Size is always relative to distance, which is why people who buy a bigger softbox and stand further back see no change at all.

How far away it is

Close light falls off fast: bright on the near cheek, dim on the far one. That falloff is what makes a portrait look three-dimensional, and it's the first thing beginners accidentally throw away by standing too far back.