How to use ND Filters on FPV Drones: Creating Cinematic FPV Videos

by Oscar
Flywoo Naked Gopro Hero 9 10 Nd Filters

Using ND filters correctly on GoPro cameras or other action cameras can significantly enhance your FPV videos, making them appear more professional and cinematic by introducing the optimal amount of motion blur. In this guide, I will explain what ND filters are and how to utilize them effectively to elevate your image quality to the next level.

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ND Filter Recommendations

Get your ND filters for the GoPro here. A set of ND32, ND16 and ND8 will get you pretty much all covered:

What are ND Filters?

ND stands for “Neutral Density.” An ND filter reduces image exposure without altering the color of the image. In drone photography, these filters are particularly significant due to the unique nature of drone cameras. Unlike traditional cameras with multiple light control mechanisms, drone cameras primarily rely on ISO and shutter speed. On bright days, achieving the desired shutter speed becomes challenging. This is where ND filters come in, helping maintain optimal exposure and shutter speed.

For cinematic FPV shots, we typically aim to set the shutter speed to a fixed value relative to the frame rate we are using, adhering to something called “the 180-degree rule” (which I will explain shortly). This technique creates realistic motion blur, making the video appear “more cinematic.” However, when we do this, the image might inevitably be overexposed in bright environments, which is when ND filters come into play (to reduce exposure).

Here’s a video comparing high shutter speed without an ND filter to lower shutter speed (fixed) with an ND filter. The latter has more motion blur, giving the video a distinct feel.

Shutter Speed and Motion Blur

Flywoo Gp9 Naked Gopro Fpv Action Camera Connect Wifi Quik App

Before diving into the specific settings to use on your GoPro, it’s helpful to understand the basics of photography if you’re new to the subject.

Three factors control the exposure of an image:

  1. Aperture
  2. ISO
  3. Shutter speed

Aperture determines how much light reaches the image sensor. As you decrease the aperture, more light enters, and the image becomes brighter.

ISO refers to the digital gain applied to the brightness of an image. However, it’s the last setting we want to adjust, as increasing ISO also makes the image noisier.

Shutter speed indicates how long the camera’s shutter remains open to let light in. Digital cameras like the GoPro don’t have mechanical shutters, so the term refers to the duration the image sensor samples the frame.

Shutter speed affects motion blur in our FPV videos. As you decrease shutter speed, the shutter is open for longer, causing movements within that frame to blur together, creating motion blur.

Here is an example: from left to right, the shutter speed is progressively lowered while using a higher ND filter to maintain the same exposure level. There’s more motion blur on the right.

Keep in mind that too much motion blur isn’t always a good idea, as it can make your video appear out of focus. That’s why it’s crucial to know the optimal amount of motion blur needed. It’s best to follow the 180-degree rule, which I will explain below.

The 180-Degree Rule

The 180-degree rule is simple: set your shutter speed to one over twice the frame rate. For example, for 30 fps, set the shutter speed to 1/60, or for 60fps, set shutter speed to 1/120. This is referred to as a shutter angle of 180 degrees, as to why, is beyond the scope of this post.

Following this rule should provide an appropriate amount of motion blur. If you desire even more motion blur, you can try a shutter angle of 360 degrees (the maximum limit), which means setting the shutter speed equal to the inverse of the frame rate. For example, at 30 fps, set the shutter speed to 1/30. However, some people may consider this to be “too much motion blur.” You can also experiment with shutter angles between 180 and 360 degrees, but most individuals will likely be satisfied with the 180-degree rule.

The same principle applies to high frame rate or slow-motion shots. For example, for 240 fps, you’ll want to increase the shutter speed to achieve the same amount of motion blur, e.g., to 1/480.

The 180-degree shutter rule works best with stabilized, such as predictable camera movements on a slider or gimbal. However, for dynamic, shaky situations like FPV drone or action-camera shots, it can lead to excessive blur. Instead, faster shutter speeds (90° or even 45° rule) might work better, reducing motion blur and facilitating better post-stabilization results, because footage that’s too blurry might not work well in digital image stablization. With 90° rule, set shutter speed to 1/120 for 30fps, or set it to 1/240 for 60fps (one over four times the fps). With 45° rule, set shutter speed to 1/240 for 30fps, or set it to 1/480 for 60fps (one over 8 times the fps).

To sum it up, 180° works well for slow, relaxed cruising shows. 90° is better for more rapid and shaky shots. Experiment and see what works best for you.

Why Use an ND Filter?

With a fixed shutter speed, you can only use aperture and ISO to change image exposure. However, GoPro cameras don’t have an aperture setting, which leaves us with ISO – the last parameter we want to increase due to the increased image noise it introduces.

When shooting outdoors with a GoPro, you might find that even when the ISO is set to its lowest value (at 100), the image is still too bright and overexposed. This is when an ND filter comes in handy, as it reduces the amount of light entering the camera.

How to Use an ND Filter?

GEPRC Naked GoPro 8 Case nd filter

I highly recommend using ND filters on your GoPro. They not only improve video quality by introducing the right amount of motion blur but also act as a lens protector in the event of a crash.

ND filters come in various strengths: ND2, ND4, ND8, ND16, ND32, ND64, or even higher. The strength number indicates the amount of light reduction, with a larger number signifying greater reduction.

 

Nd Filter Fpv Nd2 Nd4 Nd8 Nd16 Nd32 Effects Brightness Exposure

Your choice of ND filter depends heavily on the environment and lighting conditions. Here are my personal recommendations:

  • ND32: Snowy day
  • ND16: Sunny day
  • ND8: Cloudy day, or early morning and late afternoon in sunny conditions
  • ND2 and ND4: rarely used
  • No ND: Just after sunset

It’s important to actually check your image exposure (preview) before shooting to avoid surprises.

Here are my full GoPro settings for optimal results.

Get your ND filters for the GoPro here. A set of ND32, ND16 and ND8 will get you pretty much all covered:

Some ND filters can be stacked on top of one another to increase the reduction. While this isn’t always possible, it’s useful to know. For example:

  • ND2 + ND4 = ND8
  • ND4 + ND4 = ND16
  • ND4 + ND8 = ND32

Can ND Filters Remove Jello?

“Jello” is a phenomenon that appears when the camera vibrates. Jello in FPV videos can be caused by various factors, such as poor PID tuning, damaged frames or propellers, and faulty motor bearings.

In my experience, ND filters can reduce jello to some extent. However, if there are significant vibrations in your drone, instead of displaying up-down or left-right motions, the ND filter blurs the movements together, making everything appear soft and out of focus. This property can be beneficial to FPV videos in some situations, but I would not rely on an ND filter solely for the purpose of reducing jello. It is crucial to address the vibration issues in your drone when experiencing jello and not just “apply a Band-Aid to the root problem.

Edit History

  • Apr 2018 – post created
  • Dec 2022 – updated

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7 comments

maxo 9th December 2022 - 9:16 pm

if you use ND with hypersmooth and reelsteady you get terrible video even if you in 180degree rule

Reply
Oscar 9th December 2022 - 10:50 pm

I use reelsteady all the time, no problem with ND filters.

Reply
Nikola Zagorski 16th July 2024 - 10:24 am

I am struggling with Gyroflow and the 180 degrees rule. The video gets really messed up. Now I will try the 45 degrees rule with ND16 filter and see how it goes.

Reply
Mactac 21st July 2019 - 2:34 am

Hey Oscar, I just wanted to chime in and let you know that I make very high quality glass stick-on filters for the session. They can be put on, taken off over & over, and they are available in ND4, 8, 16 and 32. They are MUCH better than the window tint ones, and you don’t need a special mount, and they only cover the glass of the camera, so you can fit them on even when using TPU mounts.

They are available at camerabutter.com

Happy to send a couple to you if you want to check them out, just let me know. I can give you some tips on how to get the most out of filters in general as well.

Reply
Dan 5th May 2019 - 8:39 am

Do you have some settings tips for ND filters on the Session 5?

Reply
Lee 28th May 2018 - 6:37 pm

Nasty lens flare is light coming in from the edges of the glass. Some matt black nail paint would solve that.

Reply
KuzyaTron 9th May 2018 - 4:22 pm

Thank you so much for the last pictures!!

Reply