The main issue when lighting fails on video conferencing calls is the “Shady Face” factor. This is when half of the face is shaded or blocked in some way. We recommend having one steady lamp, directly by your face, for an even, steady lighting.
If you are presenting as opposed to attending a meeting, three lights at different angles is optimum with no sidelight or backlight. For the best result, situate yourself facing the window to ensure the light has balance.
Avoid having the light behind you because the camera adjusts to light levels and as you move the camera compensates and continuously adjusts silhouetting which can be very distracting for the viewer on the other side.
If you must have your back to a window, draw the curtains and have a good light source illuminating your face so as to avoid the ‘shady face’ concept.