1.There should be provision for focusing the source relative to the lamp condenser/diaphragm. 2.If the microscope requires different light sources, they should be easily interchangeable, ideally without upsetting the lamp alignment. 3.Lamp tilt, rotate, and distance from the microscope must be easily adjustable, and once set, should be sufficiently rigid to resist accidental misalignment. 4.Filters etc. should be easily removable and replaceable, and preferably located well forward of the lamp condenser. 5.The condenser/diaphragm assembly should be easily removable, and its components easily separated for cleaning. 6.Focusing of the source should be possible without altering the distance of the lamp condenser from the microscope. 7.The lamp should not become too hot for comfortable handling.