Neutral Density filters allow precise control of light reaching the sensor, both for photography and video. Reducing the amount of light make possible to reduce the shutter-speed and practise long-exposure, while in video this reduction of light will allow to use wide aperture such as F1.4 for bokeh even in bright light conditions to maiain the 1/50e sec shutter speed depending your needs. HOYA use an exclusive coloring process named ACCU-ND for uniform deposit of color resulting in accurate density value and perfect color neutrality. HOYA PRO ND-EX filters reduce equally trasmittance in visible and infrared spectrum. HOYA PRO ND-EX8 reduce the light by 3f.stops (T%= 12,5%), PRO ND-EX64 by 6f.stops (T%= 1,56%) and PRO ND-EX1000 by 10f.stops (T%= 0,10%) making it the most popular filter for long-exposure. HOYA ultra-clear optical glass is precisely inserted in aluminium ring with back and front thread to install lens cap. It's possible to stack filters and therefore reach different densities, for example combination of a PRO ND-EX8 and PRO ND-EX64 will reach 9 f.stops density equivalent to PRO ND-EX500 (T%=0,20%). It's highly recommended to proceed vignetting test before shooting. HOYA PRO ND-EX filters are available from diameter ø49mm to ø82mm.