Time for action — adjusting the falloff
Now that the scene is set, check out how much you can vary the light without ever changing how much energy the light emits:
In the Lamp subpanel of the Properties window, click on the Sun button.
Press F12. No falloff. Sunlight does not get dimmer, only spot lights, point lights, and area lights get dimmer.
In the Lamp subpanel, click on the Spot button.
Press F12.
In the Lamp subpanel, change the Falloff: Distance: from 25 to 12.
Press F12.
In the Lamp subpanel, set the Falloff: Distance: to 50.
Press F12.
In the Lamp subpanel, set the Falloff: Distance: to 100.
Press F12. Press Esc when you have finished looking at the image. Compare what you have seen in the three renders, as shown in the following screenshot:
What just happened?
This Time for action section brings up a good question. If light can travel distances so far that it takes the light billions of years to get there, why does light get dimmer in just crossing a room? Shouldn't it stay just as bright...