Light modifier

A bare bulb or panel gives hard light with sharp-edged shadows. Modifiers change the size of the source relative to the subject, and size is the one thing that makes light soft, which is what a big diffused panel is doing when it flatters a face that a small bright one flattens. A softbox or umbrella enlarges the source and wraps the shadow edges. Grids and snoots narrow the beam instead. Flags and black card subtract light rather than adding any, and that subtraction is what most home setups are missing when a room looks flat and evenly lit.