The Fastest Way to Pick the Right ND Filter (and Nail Your Exposure)
We’ve just launched a new free app called ND Meter by Camera Butter. It uses your phone’s camera to measure light and instantly recommend the right ND filter strength and camera settings for your GoPro, action camera, drone, or mirrorless setup.
It's for both Android and iPhone, and you can download it here: CameraButter.com/ndmeter.
If you’ve ever just guessed which ND filter to use, then had to fiddle with changing it because it wasn't exactly right, or even worse - you shot an entire session, and only later discovered that your footage was blown out or under exposed ND Meter is designed to fix exactly that.
Watch ND Meter in Action
This short video shows how quickly you can go from pointing your phone at the scene to having dialed-in ND filter and camera settings ready to go:
Why Choosing the Right ND Filter can be Tricky.
On paper, picking an ND filter looks simple: bright day, higher ND; cloudy day, lower ND. In real life, it’s a lot messier:
- Outdoor light is constantly changing. Clouds roll in, you move into shade, sun reflects off snow, water, or pavement.
- ND choice is mostly guesswork. You grab an ND16 when you really needed ND32, or you just leave yesterday’s filter on and hope for the best.
- Shutter speeds get weird. To fix exposure, you crank the shutter and end up with choppy, “video-ish” motion instead of smooth, cinematic motion.
- It can slow down your workflow. Fiddling with getting the exact right filter can take time, and we often get lazy and just go with something "Close enough". Your shutter speed (and amount of motion blur) will be wrong, or it will be inconsistent from shot to shot, ruining the flow of your video masterpiece.
The result: wasted sessions, inconsistent motion blur, and footage that looks nothing like what you were going for in your head.
What ND Meter Does
ND Meter turns your iPhone into a fast, purpose-built exposure tool for video shooters. In a few seconds it:
- Measures the light in your scene using the iPhone’s camera.
- Applies your frame rate and motion blur preference.
- Recommends the correct ND filter strength.
- Shows suggested shutter speed and ISO if you are in "Pro" mode. In "Easy" mode, it assumes auto shutter, and will suggest ISO settings only.
- Displays a live histogram with a movable blue outline to preview exposure compensation.
- Highlights clipped whites/blacks in red on the histogram.
- Shows a preview alert when lighting has changed significantly.
- Shows approximate white balance.
- Generates a GoPro Labs QR code for instant camera configuration.
Why ND Meter Is Actually Useful (Not Just Another Camera App)
- Fast workflow: Correct ND + shutter + ISO in 5 seconds.
- Fewer ruined clips: Correct exposure = consistent footage.
- Action cams: Avoid auto-exposure inconsistency.
- Vloggers: Smooth transitions through changing light.
- FPV pilots: Correct ND before takeoff.
- GoPro Labs: One scan = full config.
- Stabilization-aware: Uses slightly faster shutter speeds for certain activities when stabilization is enabled.
- Supports every camera that allows you to change shutter/ISO settings.
How to Use ND Meter
Here’s a simple run-through of how a typical setup works:
- Select your camera profile in settings (you can create new camera profiles if yours is not listed)
- Point your phone at the scene.
- Select frame rate.
- Set your desired motion blur with the slider.
- Adjust exposure compensation if desired.
- Tap Measure ND.
- Install the recommended ND filter.
- Dial in suggested shutter/ISO (or scan the QR code for GoPro Labs).
- Re-measure if the preview warns you lighting has changed.
- If you find that your camera is consistently under or over exposing using the suggested settings, change the EV bias in your camera profile in settings.
Instant GoPro Setup with GoPro Labs QR Codes
If you’re using a GoPro with GoPro Labs, ND Meter can configure your camera automatically:
- Tap the QR icon on the Suggested Settings screen.
- Point your GoPro at the QR code until it beeps.
- Your camera instantly applies the shutter, ISO, white balance, and more.
This produces a complete one-tap workflow: measure → install ND → scan → shoot.
Pro Tips for Getting the Best Results
- ND filters are mainly used for outdoor shooting where there is sufficient light. If you use it indoors, it will generally suggest no ND filter.
- Meter pointing at the scene you will be filming.
- FPV/drone: Meter toward open sky and flight direction.
- Mixed lighting: Meter for the most important part of the scene.
- Histogram: Red = clipping. Re-measure to re-calculate suggested settings.
- Exposure compensation: Use it when you want brighter/darker mood.
- EV bias: Settings/Camera profile - change this if your camera is consistently under or over exposing.
- Preview warning: Re-measure when light changes significantly.
- White balance: Use the WB reading to match footage between shots.
Who ND Meter Is For
Get ND Meter (It’s Free)
ND Meter is a small, focused tool: it helps you pick the right ND filter and camera settings fast, so you can spend your time riding, flying, or filming instead of fiddling with different filters and settings.
The app is free and currently available for iPhone and Android. Download it here: CameraButter.com/ndmeter.