Today I would like to talk about how to paint with light. You don’t need much to experiment with this kind of shot, just make sure you have the following items: a camera capable of long exposures, a flash light, a tripod and of course a dark room / location - make sure there is no other light around you and the subject. This is all you need.
And here comes the magic. Set your exposure to a long value and stop down the aperture as much as you need. Now press the shutter button. Shutter is open now time to take action and use the flash light, use it as a pen, this is the art and fun part.
Those areas where you will go slowly will be more lit. Make sure you do not take too much time at one spot because you will burn it. Make sure when you are painting you focus on the lens. What I mean is while you are drawing in the air you need to point towards the lens. Your starting point is towards the lens and when you slide your flashlight to your ending point will be again towards the lens. Continue until the shutter closes.
If you would like to painting with light during daytime it is possible too. You are going to need an ND filter (maybe 2 of them attached to the camera to make the surrounding even darker).