Introduction to how aluminum foil is used in shooting: aluminum foil is cheap, light and takes up very little space. By sticking it on the computer monitor, it can create an efficient reflective surface for low-brightness flashlights, or it can be used as a moldable shutter. Alternatively, it can be made into a "reflector" on optical sensors with unstable sensitivity to flashes, absorbing light and reflecting it back to the sensor... Using aluminum foil allows for creative use of flashes.