Which luminescence applications require filters?
For example, you can read ATP and luciferase based assays (e.g. CellTiter Glo or DLR measurements from Promega) without filters. There are, however, some luminescence applications that need filters, for example BRET assays. BRET assays are luminescence energy transfer assays where you need to measure two emission wavelengths. Here it is necessary to measure each emission with a different filter.