The filter has an index setting that allows the photographer to determine the required density between +1 and +5 f-stops. To avoid imaging errors, the light reduction cannot be set above a critical value. The color reproduction remains constant over the entire setting range. This means that the B+W ND vario filter achieves professional imaging performance even with high filter factors. The effect of the B+W ND vario filter can be infinitely adjusted to the most diverse motif situations. Often a large aperture is desired in order to optically separate the main subject from the background, or deliberately long exposure times in order to make flowing water soft and fragrant. The B+W ND vario filter is ideal for DSLR video when a specific aperture is required.