Unless the actor is really stalling, I remind myself that 1) actors can't move til the ghosting is out, not just the lamp 2) actors are moving from brightly lit to totally dark, while crew is moving from less dark onto more dark - I have had actors who are legally blind and had to be escorted off, or laid landing patterns in glowtape on the floor - and the crew has to adjust around such things - it's amazing how creative you can get when you have to get around actors whose eyes haven't adjusted or can't move fast enough - and of course, we can suggest better actor exist to make all our lives easier.