A 45x60 black flag (probably refers to a light -sculsing black flag or grid for light) is used in filming to control the lighting and create certain effects.
The main features:
Light control: Black flag can be used to dimin down certain sections of the stage or object, which helps to create more contrasting and saturated Images. It blocks light and prevents it from entering certain sections of the frame.
restriction of light scattering: the flag can be used in studio conditions or on the street to prevent lighting from flashes or light sources, thereby ensuring a more accurate direction of light rays.
Shadow management: a black flag can help create shadows or reduce their size, which is useful when shooting portraits or objects to get the desired visual effect.
Hiding unwanted elements: it can used to close unwanted light sources or elements on the stage that can spoil the frame.
Creating a shape of light: the flag can be used to control the shape of the lighting and create various effects, such as the lighting of the contours of the object or the creation of the framework from the world Around the subject.