To Create a Photometric Spotlight

1. At the command prompt, enter lightingunits and set the value to 1 (American units) or 2 (International SI units) for photometric lighting.
2. Click Modeling tab > Render panel > Light drop-down > New Spotlight.
3. Click in the drawing to specify a location for the light.
4. Click to specify a target for the spotlight.
5. If the LIGHTINGUNITS system variable is set to 0, the following prompt is displayed: Enter an option to change Name/ Intensity/ Status/ Hotspot/ Falloff/ shadoW/ Attenuation/ Color/ eXit] <eXit>:
6. If the LIGHTINGUNITS system variable is set to 1 or 2, the following prompt is displayed: Enter an option to change [ Name/ Intensity factor/ Photometry/ Status/ Hotspot/ Falloff/ shadoW/ Attenuation/ filterColor/ eXit] <eXit>:
Note: When the LIGHTINGUNITS system variable is set to 1 or 2, the Attenuation option has no affect on the creation of the light. It is only maintained for scripting compatibility.
7. At the Command prompt, enter n and enter a name. This name will appear in the properties and in the Lights in Model window.

   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.

8. Press Enter twice to exit the command.
9. Select the light and use grip tools to change the light.