ND Filters Explained: Complete Guide on ND, CPL, and ND/PL Filters

Are ND Filters Necessary? What Type of ND Filters Should You Use? What’s the Difference Between ND, ND/PL, and CPL Filters? There are many myths and misconceptions about these filters, along with a lot of false information on the internet. In this post, I want to clearly explain what ND filters are really for and how to make the most out of drones like the DJI Air 3, Mavic 3 Pro, or DJI Mini 4 Pro.

I also want to show you what, in my opinion, are the best filters available. Freewell offers filters for any drone, DSLR/Mirrorless camera, or action camera. I’ve been using Freewell filters for a long time and I’m really happy with their performance.

Below, I’ve included a video explaining everything you need to know about these filters:

What are ND filters?

ND filters (Neutral Density Filters) are accessories that are placed in front of the camera or drone lens to reduce the amount of light entering the sensor, allowing for the use of slower shutter speeds. They are like a kind of sunglasses. These filters combine very well with color editing LUTs.

Why is it important to reduce the amount of light entering the sensor? Basically, having a correct shutter speed will allow you to achieve that blur effect or “motion blur” and make your shots more cinematic.

There are several levels. For example, we have ND8, ND16, ND32… the higher this value, the less light it will let into the sensor. To give you an idea, here are some tips so you know which ND filter to choose:

  • ND4 to ND8: Moderate light situations, such as cloudy days.
  • ND16 to ND64: Situations with bright sunny days.
  • ND1000 or higher: These filters are used for long exposure photos in bright daylight.
ND Filters

How should we use ND filters?

To use ND filters correctly we need to know the 180º rule. What this rule tells us is that our shutter speed has to be double the fps we are recording at. For example, if we are recording at 30fps, our shutter speed should be 1/60. If we are recording at 60fps, the shutter speed will have to be 1/120. And so on.

ND filters are best used in situations where we have moving subjects, we are flying close to the ground or we want to focus on a main subject and blur the rest. If, for example, we are flying at a high altitude or we are recording a landscape with no movement, we will not need it.

CPL Filters

CPL (circular polarized) filters are completely different. These filters do reduce reflections and increase contrasts in water or the sky. These filters, for example, are very useful if we are going to record on the beach and there are reflections in the water, if we are recording buildings or even to reduce reflections in the snow.

ND/PL Filters

ND/PL filters are filters that combine the properties of ND and CPL filters in a single filter. These filters make your work much easier, since you don’t have to keep changing filters and you have everything together. ND/PL filters are useful, for example, in situations where there are sunny days with moving subjects or, for example, if you are recording a cliff with water that could also reflect us.

Freewell has quite a few packs that combine all kinds of filters, including additional filters such as Mist, LPR or UV. Mist filters reduce contrasts and amplify lights to achieve a fog-like effect, and UV filters reduce ultraviolet rays. Without a doubt, Freewell filters are an excellent investment for your drone or camera and, personally, it is something that you can 100% use to improve your shots and videos.

If you are interested in knowing more about the subject, I leave you the Freewell website here: https://www.freewellgear.com/en/dji-air-3-nd-filters/1132-dji-air-3-mega-12-pack.html?affp=55619