Neutral Density (ND) filters are essential tools for drone pilots looking to capture professional-quality aerial footage. Think of them as sunglasses for your drone’s camera, reducing the amount of light that enters the lens. This allows you to control shutter speed and aperture, resulting in smoother, more cinematic videos and well-exposed photos, even in bright conditions.
What are ND Filters and Why Use Them on Drones?
An ND filter is a darkened piece of glass or resin that reduces the amount of light entering the camera lens, without affecting the color or clarity of the image. Here’s why they are so important for drone photography and videography:
- Controlling Exposure: In bright sunlight, a drone’s camera might automatically select a very fast shutter speed to avoid overexposure. ND filters allow you to use slower shutter speeds, which is crucial for achieving a cinematic look.
- Achieving Cinematic Motion Blur: A slower shutter speed creates motion blur, which makes videos look smoother and more natural. Without an ND filter, fast shutter speeds can make footage appear jerky and unnatural.
- Managing Aperture: ND filters allow you to control the aperture, which affects the depth of field. This is especially important for creating a shallow depth of field, where the subject is in focus and the background is blurred.
- Preventing Overexposure: ND filters prevent overexposure, which can wash out colors and lose details in highlights, especially when flying in bright conditions like sunny days or snowy environments.
- Color Correction: By limiting the light, ND filters make it easier to color-correct your footage during post-production.
Understanding ND Filter Numbers
ND filters come in various strengths, each reducing light by a different amount. The strength is indicated by a number, which can be confusing. Here’s a simple breakdown:
- ND2: Reduces light by 1 stop (50% reduction). Ideal for low-light or overcast conditions.
- ND4: Reduces light by 2 stops (75% reduction). Suitable for early mornings or late afternoons.
- ND8: Reduces light by 3 stops (87.5% reduction). Best for moderately bright conditions, like cloudy days.
- ND16: Reduces light by 4 stops (93.75% reduction). Ideal for bright days with lots of sunlight.
- ND32: Reduces light by 5 stops (96.875% reduction). Perfect for very sunny days or bright environments.
- ND64: Reduces light by 6 stops (98.4375% reduction). For extremely bright conditions, like beaches or snowy environments.
- ND128 and higher: Used in specialized cases for very long exposure shots or extreme brightness.
Different notation values can quantify lens density, including “ND number,” “ND1 number,” and “ND. number.”
Choosing the Right ND Filter
Selecting the correct ND filter depends on the lighting conditions and the desired effect. Here’s a general guide:
- Overcast or Cloudy Days: ND4 or ND8
- Partly Cloudy Days: ND16
- Sunny Days: ND32 or ND64
- Extremely Bright Conditions (Snow, Beach): ND64 or higher
It’s better to have a set of filters with varying strengths so you can adapt to different lighting conditions. Many kits include ND4, ND8, ND16, ND32, and ND64 filters.
How to Use ND Filters with Your Drone
Here’s a step-by-step guide on how to use ND filters to get the best results:
- Attach the Filter:
- Drone filters usually twist or clip onto the camera lens.
- Make sure the filter is securely attached to prevent it from falling off during flight.
- Set Camera to Manual Mode:
- Use a specific DJI app and set your drone’s camera to manual mode.
- Manual mode allows you to control ISO, shutter speed, and aperture.
- Adjust ISO:
- Keep the ISO as low as possible (ideally ISO 100) to minimize noise.
- Disable auto ISO to prevent the camera from automatically increasing it in darker conditions.
- Set Shutter Speed:
- A general rule is to set the shutter speed to twice your frame rate (the 180-degree shutter rule).
- For example, if you’re shooting at 30fps, set the shutter speed to 1/60th of a second.
- Adjust the ND filter to achieve this shutter speed without overexposing the image.
- Adjust Aperture (if possible):
- Some drones have a fixed aperture, while others allow you to adjust it.
- Choose an aperture that gives you the desired depth of field.
- A smaller aperture (higher f-number) increases depth of field, while a wider aperture (lower f-number) decreases it.
- Check Exposure:
- Use the drone’s built-in exposure meter to check the exposure.
- Adjust the ND filter or shutter speed until the exposure is correct.
- Monitor and Adjust:
- Lighting conditions can change quickly, so monitor your exposure and adjust the ND filter or settings as needed.
Tips for Using ND Filters
- Invest in a Good Set: High-quality ND filters are made from optical glass and have multiple coatings to prevent reflections and distortions.
- Consider Variable ND Filters: These filters allow you to adjust the strength of the filter by rotating the lens. This can be convenient, but they may not offer the same image quality as fixed ND filters.
- Clean Your Filters: Keep your filters clean to prevent smudges and streaks from appearing in your footage.
- Use a Polarizing Filter (CPL): Use a circular polarizing filter to reduce glare, enhance saturation, and clear through haze and reflections.
- Experiment with Long Exposures: On calm days, try using strong ND filters to create long exposure photos with your drone. This can create unique and surreal effects.
- Consider an ND/PL Filter: These combine the effects of a neutral density filter and a circular polarising filter.
Best ND Filter Brands for Drones
While the “best” brand is subjective and depends on individual needs and preferences, some brands consistently receive high praise for their quality and performance. Here are some of the top ND filter brands for drones:
- DJI: For a straightforward option, the OEM DJI filters are a reliable choice.
- Freewell: Freewell Gear is a popular choice, known for offering high-quality ND filters at an affordable price.
- PolarPro: Popular with aerial filmmakers and photographers, providing reliable options for photography and filmmaking needs.
- PGYTECH: Offers reliable options for drone photography and filmmaking needs.
- K&F Concept: It has a solid reputation for making quality filters for DJI drones.
- NEEWER: Known for making quality filters for DJI drones.
- SKYREAT: Known for making quality filters for DJI drones.
Shopping on Amazon will also give you the opportunity to check out reviews from people who have purchased and used the products.
Common Mistakes to Avoid
- Underexposure: Using too strong of an ND filter can result in underexposed footage. Monitor your exposure and adjust accordingly.
- Incorrect Filter Selection: Using the wrong ND filter for the lighting conditions can result in overexposed or underexposed footage.
- Not Cleaning Filters: Dirty filters can cause smudges and streaks in your footage. Clean your filters regularly.
- Forgetting to Adjust Settings: Make sure to adjust your camera settings to compensate for the ND filter.
Achieving a Cinematic Look
To achieve a cinematic look with your drone footage, follow these guidelines:
- Use ND Filters: As discussed, ND filters are essential for controlling shutter speed and achieving motion blur.
- Shoot in 24fps or 30fps: These frame rates are standard for cinematic footage.
- Maintain a 180-Degree Shutter Angle: Set your shutter speed to twice your frame rate (e.g., 1/48th or 1/60th of a second).
- Color Grade Your Footage: Use color grading software to adjust the colors and contrast of your footage.
- Fly Smoothly: Practice smooth and controlled drone movements to avoid jerky footage.
Final Thoughts
ND filters are an invaluable tool for drone enthusiasts and professionals alike. By understanding how they work and how to use them effectively, you can capture stunning aerial footage that looks smooth, cinematic, and professional. With the right ND filters and techniques, you can elevate your drone videography and photography to new heights.
