In AutoCAD 2007-based products and earlier releases, lights didn't support photometric lighting and more advanced lighting features. Before lights from earlier releases can affect the lighting in a scene, the lights must be converted to the newer lighting system. To convert lights from earlier releases, you can use either the 3DCONVERSIONMODE system variable or CONVERTOLDLIGHTS command.
Note: Starting with AutoCAD 2016-based products, the renderer calculates all standard lights as photometric lights. It is recommended to update all standard lights in a scene to photometric lights. You can enable photometric lighting by setting the LIGHTINGUNITS system variable to 1 or 2. However, changing the value of the LIGHTINGUNITS system variable isn't enough. You will need to adjust the properties of each time as well because of the way attenuation is calculated for photometric lights.