Reflector is used to reflect light obtained directly to your subject and illuminate the shooting area you use. Reflector displays colors in various sizes (can be to warm and give cool to your subject) and the most remarkable thing about this tool is that you can see what the results will be like before you shoot. Hold the reflector and point it to the corners you want until you get the results you expect. You may need someone's help to hold your reflector during shooting or you can put it facing the wall or the floor. Another option that you can use also is to place your reflector on the lighting stand.
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From @pujaisma