For physically accurate results, the various values should be left as a default of 1.0 and for Max.

In the Contribution rollout, you can use the advanced options to control the aspects of light contribution in the final rendering.

The Atmospheric Shadows option controls the calculations of volumetric shadows.

In the Shadow rollout, you can toggle the casting of shadows from the light on or off.

Increasing the Samples value reduces the noise in shadow areas, but increases the render time.

In the Rendering rollout, you can adjust the quality of specular highlight and shadows.

Exposure is an intensity multiplier and increases the intensity in multiple jumps. Typically, you are required to adjust the Intensity or Exposure of the light source to get a good render of a scene.

In the Color/Intensity rollout, you can set the color of the light source.

The parameters in the Shape rollout are based on the type of light selected. By default, the Quad option is selected, which illuminates a rectangular area and emits the light only in one direction. The shape selected controls how the light is emitted. In the Shape rollout, you can select the shape of the light.

By default, Targeted is cleared, which automatically creates the light as a free light. You can also set the light as either free or targeted. In the General Properties rollout, you can toggle the light on or off.In the Object Type rollout, click Arnold Light. You can open the Arnold lights from the Command Panel’s Create panel ( )> (Lights) by selecting Arnold from the list, as shown here.

3ds max arnold render