Neutral density/polarization filters, or ND/PL filters for short, are a unique type of camera filter that combines two popular filter effects together into one single lens. ND/PL filters combine a polarized lens with a neutral density coating of a specified strength, to achieve smooth video or photos at slower shutter speeds with improved contrast and color saturation.
In cinematography, neutral density filters are used to control shutter speed, using the 180 degree shutter angle rule as a guide. In today’s digital terms, the 180 degree shutter angle principle corresponds to a shutter speed to frame rate ratio of 2:1. To achieve smooth video with natural looking motion blur, cinematographers use ND filters to achieve this 2:1 ratio. In environments where there is too much harsh light from extreme glare or haze, ND/PL filters can be used as a direct replacement for ND filters to reduce shutter speed and also polarize the scene.
Common strengths of ND/PL filters include ND4/PL, ND8/PL, ND16/PL, ND32/PL and ND64/PL. Unlike normal ND filters that strive to have a neutral color profile, ND/PL filters provide more color saturation due to the polarization aspect. For example, a ND4/PL reduces shutter speed by 2 stops while increasing color saturation, while the larger stop ND64/PL reduces shutter speed by 5 stops while also improving contrast and increasing color saturation. The ND4/PL is suitable for sunrise, sunset or similar low light conditions, while the ND64/PL is reserved for shooting at 24p in extreme light.
Aerial cinematographers as well as GoPro users shooting at the beach or in other bright and reflective scenes often use these hybrid ND/PL filters instead of regular polarizing or neutral density filters to get the benefits of both ND and PL filters in one lens element. ND/PL filters are also being utilized with full frame, production grade digital cameras, with companies like PolarPro setting the bar with the recent release of the QuartzLine, which features a few different ND/PL options for full frame DSLR and mirrorless shooters.
Shooting through one ND/PL lens element, especially with a drone camera that is prone to camera shake and atmospheric noise, will produce better results than stacking polarizing and ND filters to achieve the same benefits. ND/PL filters also add less weight to a camera gimbal than stacking filters. And after all, the idea of a camera filter is to help enhance your image, not to introduce noise or damage your expensive equipment.
If you’re looking for some ND/PL filters for your DJI drone, GoPro or full frame DSLR/mirrorless camera, be sure to check out PolarPro’s full production-grade filter line.