To create a photometric spotlight and change photometric properties
Lights
panel
Lighting
Units drop-down
Generic
Lighing Units.
No lighting units are used and standard (generic) lighting is enabled.
Lights
panel
Create
Light drop-down
Spot.
You can continue to specify properties by entering options, or you can exit and set properties interactively. When you use the interactive method, you can see the results of your changes as you work.
Select the light and use grip tools to change the light.
Toolbar: Lights