Converting lights from previous versions.
With AutoCAD 2008, you can choose either standard (generic) lighting or photometric lighting. Prior to AutoCAD 2008, the only option was standard (generic) lighting. There is no explicit conversion required for lights from AutoCAD 2007 to AutoCAD 2008. Drawings from AutoCAD 2007 will open by default in AutoCAD 2008 in the standard (generic) lighting workflow. The additional photometric properties available in AutoCAD 2008 are available as soon as you turn on the photometric lighting workflow in your drawing.
There is a conversion process required when opening drawings with lights prior to AutoCAD 2007. The 3DCONVERSIONMODE system variable is set by default to convert drawings with lighting from previous versions to the AutoCAD 2007 and AutoCAD 2008 lighting format. The system variable has three settings. If the variable is set to 0, no automatic conversion will take place. If it is set to a value of 1, the default value, the conversion will take place automatically. If the value is set to 2, then the user will be prompted when lights need to be converted and will have the option to convert or not to convert.
You can use the CONVERTOLDLIGHTS command to convert the old lighting manually.