The Light Color setting on the Light Properties panel modifies the color for the current light.

Light Intensity lets you set the brightness for the current light. You can drag the mini-slider to set a value between 0% and 100%, or enter a numeric value manually. You can even enter values greater than 100%. This is sometimes necessary, particularly when using radiosity (Global Illumination panel.

Note: The default light is set at 100%; however, lights added subsequently have a 50% Light Intensity setting.

The intensity of lights is additive, so if multiple lights hit a surface, their intensities are added together. As such, too high a Light Intensity value tends to wash out a scene, particularly when you have multiple lights. Eventually, the rendered image becomes solid white where the values of light sources exceed a certain brightness.

Note: A surface hit with multiple lights that exceed a total of 100% is not necessarily a bad thing, and usually occurs in most scenes. Elements like surface Diffuse values, shadows, light falloff, and so on, will all tend to diminish the initial light intensities.

Light Intensity Tool

You can use the Light Intensity tool to adjust the intensity of selected light(s) by dragging your mouse.

Negative Lights

The Light Intensity can also be set to a negative value. This takes away Diffuse and Specular shading. Moreover, if you use a colored light, that is, something other than white, a negative light subtracts the light color from the surfaces it affects.

The Envelope Please

Numeric light properties can use envelopes to control their values over time. A highlighted E button signifies that an envelope is in use. Clicking on the E button allows you to make changes to an envelope in the Graph Editor. SHIFT + LMB on a highlighted E button removes the envelope.

Point lights, as well as Spotlights, can be set to fall off over a specified distance. You activate the option on the Intensity Falloff pop-up menu. The falloff can be Linear or non-linear. The non-linear option Inverse Distance reduces intensity as the light moves farther from its source. The Inverse Distance ^2 uses a higher level of reduction.

The Range/Nominal Distance values set the distance from the light where the light’s intensity is zero.

In orthogonal views, the falloff area is visible as a circle around the light. The light will fall off to zero exactly at the edge of the circle.

Note: If you do not use Intensity Falloff, the light will travel forever, unless a shadow option is active.