Focusing a light, while still leaving the falloff ""spherical"", makes it so the center of the sphere is not at the light source, it's a virtual point significantly behind it. With a narrow beam, being 1 meter from the light and 10 meters from the light might only be 2x different in brightness, or even less.
And for lights with significant width, you drift away from spherical falloff the closer you are and the wider they are. As you get quite close, and the light fills a lot of your field of view, you approach the situation of an infinite wall of light and that has linear falloff.
These lights are huge and wide and can have tight beam angles.
Focusing a light, while still leaving the falloff ""spherical"", makes it so the center of the sphere is not at the light source, it's a virtual point significantly behind it. With a narrow beam, being 1 meter from the light and 10 meters from the light might only be 2x different in brightness, or even less.
And for lights with significant width, you drift away from spherical falloff the closer you are and the wider they are. As you get quite close, and the light fills a lot of your field of view, you approach the situation of an infinite wall of light and that has linear falloff.
These lights are huge and wide and can have tight beam angles.