When using IES Light, you will need to load an IES profile by clicking on the folder icon in the editor. As soon as you load the profile you will see the shape of the IES profile in the material preview. You will also see the shape in form of a mesh in the Real-time View.
This displays the name and location of the IES profile being used. Click the folder icon to change to a different IES profile.
Here, you can choose the color the light will cast. Use the Kelvin scale to select accurate lighting temperatures.
On this page
Color = 3000 Kelvin
Color = 4000 Kelvin
Color = 5000 Kelvin
Color = 6500 Kelvin
Adjust the intensity of the light with this slider.
The luminous flux (luminous power of the light) is embedded in the IES file itself as a value in Lumen. The Multiplier adjusts this value. For the most accurate result, the Multiplier should be left at a value of 1. Values between 0 and 1 can be used to simulate the behavior of a dimmer.
Adjust the radius to control the softness of shadows cast from this light. A large radius gives soft shadows, while a small radius results in harder shadows with crisply defined, sharp edges.
Radius = 0 mm (The unit depends on the Scene Units.)
Radius = 5 mm
Radius = 10 mm
Radius = 20 mm
The effect of radius depends on the size of models. Larger models may require a higher radius value for a similar effect.
Here you can control the axis of your IES Light source.
If you have imported a scene where the axis orientation is different from the one in your light sources, you don't have to rotate them - just choose the appropriate up-axis.