ONID TECH

Unlock Cinematic Action Camera Footage with the Right Filters

If you've ever watched a breathtaking action sports video with smooth, flowing water and perfectly exposed skies, you've likely seen the magic of camera filters in action. While action cameras like GoPro, DJI Osmo Action, and Insta360 are incredible tools for capturing adventures, their small sensors and fixed apertures can struggle in bright outdoor conditions. This is where ND (Neutral Density) and CPL (Circular Polarizing) filters become essential accessories for any serious outdoor videographer. In this beginner's guide, we'll demystify these filters and show you exactly how to use them to elevate your action camera footage from amateur to professional-looking.

What Are ND Filters and Why Do Action Cameras Need Them?

ND filters are essentially sunglasses for your camera. They reduce the amount of light entering the lens without affecting color balance. For action cameras, which typically have fixed apertures and automatic exposure settings, this serves a crucial purpose: controlling shutter speed to achieve proper motion blur.

The Science of Motion Blur and the "180-Degree Rule"

In videography, there's a principle called the "180-degree shutter rule" that professionals follow to achieve natural-looking motion. This rule states that your shutter speed should be approximately double your frame rate. For example, if you're shooting at 30 frames per second (fps), your shutter speed should be around 1/60th of a second. This creates just enough motion blur to make movement appear smooth and natural to the human eye.

Here's the problem with action cameras in bright sunlight: without an ND filter, the camera's automatic exposure will often select a very fast shutter speed (like 1/1000th or faster) to prevent overexposure. This eliminates motion blur entirely, resulting in footage that looks choppy, jittery, and unnatural—a phenomenon sometimes called "strobing."

ND Filter Strengths Explained

ND filters come in different strengths, measured in "stops" of light reduction. Common ND filters for action cameras include:

• ND8 (3 stops): Reduces light by 3 stops. Good for slightly overcast days or early morning/late afternoon shooting.
• ND16 (4 stops): Reduces light by 4 stops. Ideal for bright sunny days with moderate action.
• ND32 (5 stops): Reduces light by 5 stops. Perfect for extremely bright conditions like snow, sand, or water reflections.
• Variable ND: Some filter systems, like those available for GoPro cameras from brands such as ONID TECH, offer variable ND filters that let you adjust the strength by rotating the filter, providing incredible flexibility in changing light conditions.

Light Condition	Recommended ND Filter	Typical Use Case
Overcast/Shade	ND8 or None	Hiking in forests, cloudy days
Bright Sunlight	ND16	Beach days, mountain biking
Extreme Brightness	ND32	Skiing, surfing, desert adventures
Changing Conditions	Variable ND	All-day adventures with mixed light

CPL Filters: Your Secret Weapon Against Glare and Washed-Out Colors

While ND filters control light quantity, CPL (Circular Polarizing) filters control light quality. They work by filtering out polarized light—the type of light that causes glare and reflections on non-metallic surfaces like water, glass, and foliage.

How CPL Filters Transform Your Footage

When you attach a CPL filter to your action camera and rotate it to the proper angle, magic happens:

• Sky Enhancement: Blue skies become deeper and more vibrant, with white clouds that really pop
• Glare Reduction: Reflections on water surfaces are minimized, allowing you to see beneath the surface
• Color Saturation: Foliage appears richer and more saturated by reducing the "haze" of reflected light
• Window Transparency: When shooting through car or building windows, reflections are dramatically reduced

For action cameras used in outdoor sports, a CPL filter is particularly valuable for water sports (surfing, kayaking), snow sports (skiing, snowboarding), and any activity where you're dealing with reflective surfaces.

Practical Guide: How to Use ND and CPL Filters on Your Action Camera

Step 1: Choosing the Right Filter System

Most action cameras use either clip-on or screw-on filter systems. Popular options include:

• Magnetic systems: Quick to attach and remove, perfect for changing conditions
• Screw-on systems: More secure but slower to change
• Clip-on systems: Often used with protective cases

Many filter manufacturers, including ONID TECH, offer complete filter kits specifically designed for popular action camera models. These kits typically include multiple ND strengths, a CPL filter, and sometimes combination ND/CPL filters, all in a compact carrying case perfect for adventure travel.

Step 2: Setting Up Your Camera Correctly

Before attaching any filter, configure your action camera properly:

1. Set your desired frame rate (24, 30, or 60 fps are most common for cinematic looks)
2. Enable manual controls if available (some action cameras offer "Pro" or manual modes)
3. If using auto exposure, the camera will adjust ISO automatically when the filter is attached
4. For best results with ND filters, lock your ISO at the lowest setting (usually 100)

Step 3: Attaching and Using ND Filters

When using an ND filter:

1. Start by assessing the light conditions and selecting the appropriate ND strength
2. Attach the filter securely to your action camera
3. Point your camera at the scene and check the exposure
4. If the image is still too bright, switch to a stronger ND filter
5. If shooting fast action, you may need to compromise slightly on the 180-degree rule to avoid excessive motion blur

Step 4: Attaching and Using CPL Filters

When using a CPL filter:

1. Attach the CPL filter to your camera
2. Look through your camera's display or viewfinder at the scene
3. Slowly rotate the outer ring of the CPL filter while watching the effect
4. Stop rotating when you achieve the desired reduction in glare and enhancement of colors
5. Note that the effect changes with your angle to the light source, so you may need to readjust if you change camera position

Step 5: Using Combination Filters

Some advanced filter systems offer combination ND/CPL filters that provide both light reduction and polarization in one unit. These are incredibly convenient for outdoor videography where you want both effects simultaneously. When using these, remember that you'll need to rotate the filter to adjust the polarization effect while the ND strength remains fixed.

Common Scenarios and Filter Recommendations

Scenario 1: Beach and Water Sports

Challenge: Intense reflections from water and sand, overly bright skies
Solution: ND16 or ND32 filter combined with CPL filter
Result: Smooth water motion, reduced glare, vibrant sky colors, ability to see beneath water surface

Scenario 2: Mountain Biking or Trail Running

Challenge: Dappled light through trees, fast motion requiring smooth footage
Solution: ND8 or ND16 filter
Result: Natural motion blur on fast movements, properly exposed highlights and shadows

Scenario 3: Skiing or Snowboarding

Challenge: Extreme brightness from snow, blue sky contrast
Solution: ND32 filter with CPL
Result: Proper exposure on bright snow, enhanced blue skies, reduced glare from snow surface

Scenario 4: Urban Exploration

Challenge: Reflections from windows and vehicles
Solution: CPL filter primarily
Result: Reduced reflections on glass, deeper colors on buildings and streets

Maintenance and Care Tips for Your Filters

To ensure your filters last through many adventures:

• Always use a microfiber cloth to clean filter surfaces—never your shirt or rough materials
• Store filters in protective cases when not in use to prevent scratches
• For screw-on filters, be careful not to cross-thread when attaching
• Check filter mounts regularly for wear, especially if using your action camera in extreme conditions
• Consider carrying a small lens cleaning kit in your adventure pack

Conclusion: Transform Your Action Camera into a Cinematic Tool

ND and CPL filters might seem like advanced accessories, but they're actually quite simple to use once you understand their basic functions. An ND filter gives you control over motion blur, transforming choppy footage into smooth, cinematic sequences. A CPL filter eliminates unwanted glare and enhances colors, making your outdoor videos look more vibrant and professional. Together, they can elevate your action camera footage from simple documentation to compelling visual storytelling. Whether you're capturing surf sessions, mountain descents, or urban adventures, investing in a quality filter system is one of the most impactful upgrades you can make to your action camera setup. Start experimenting with different filter combinations, and you'll soon discover how these simple pieces of glass can dramatically improve your outdoor videography results.