Designed so that absolutely no color from the entire visible spectrum prevails, the neutral density filters can be used in many different contexts, depending on which type is used : uniform shading (square) or graduated shading (rectangular). Uniform ND filters reduce the quantity of light that reaches the sensor – or the film – increasing the exposure time. These filters have 3 main practical applications: emphasizing the flow of movement, reducing the depth of field, avoiding overexposure.