Freewell ND Filters with Built In Polarizer
What are ND Filters?
ND filters are also known as "Neutral Density" filters. They are placed at the front of any lens to reduce light coming through and onto the sensor. The strength of density ranges from ND4 to ND2000 with the higher values letting in less light. Good ND filters will do this without degrading the colours or sharpness of the final image.
When shooting video with any camera, including drones, you generally need a slower shutter speed. For example, shooting at 25fps requires a shutter speed of 1/50th sec for optimal results. The problem is overexposure caused by using a slow shutter in bright daylight.
Using Freewell ND Filters, you can reduce the amount of light hitting the drone's sensor. Bright conditions need stronger ND filters such as the ND32 or ND64. Duller light would only need a ND4 or ND8. These will reduce the light to enable slower shutter speeds to be used.
Typical Drone Filming Scenario for Using ND Filters
Some drones do not have a variable aperture and only have f2.8 like the DJI Air 2s. This means that more light hitting the sensor requires a very fast shutter speed for correct exposure.
If shooting at 25 frames per second and ISO 100, you would normally need 1/50th sec for smooth footage. However, without a ND filter, you will probably need to shoot at shutter speeds of 1/1000th sec for example. This can make the footage look "jittery" and unnatural.
In bright sunlight, a ND16 (or 4 stops of light) filter will allow a shutter speed of 1/50th sec instead of 1/1000th. Perfect for smooth, natural looking footage.
Freewell ND Filters for the DJI Mavic 3
The DJI Mavic 3 drone has a variable aperture ranging from f2.8 to f11. This means a ND filter isn't always necessary as f11 will reduce the light hitting the sensor by a fair amount. However, using f11 on a M43 sensor camera may cause diffraction. I would recommend no smaller than f5.6.
Shooting f5.6, ISO 100 and 1/50th sec shutter speed in bright sunlight would probably require a ND8 (3 stops of light) or ND16 (4 stops) filter.
Freewell All Day 8 Pack
The Freewell ND filter set for the Mavic 3 includes 8 filters.
- 1Polarizer Only
- 2ND4 (2 Stop) + Polarizer
- 3ND8 (3 Stop) + Polarizer
- 4ND16 (4 Stop) + Polarizer
- 5ND32 (5 Stop) + Polarizer
- 6ND64 (6 Stop) + Polarizer
- 7ND1000 (10 Stop) - No Polarizer
- 8ND2000 (11 Stop) - No Polarizer
These cover a very wide range meaning you will always be covered for any lighting conditions. Whether it is bright, midday sun or sunrise or sunsets you are shooting in, you have a suitable ND filter in this All Day 8 filter set.
Freewell ND Polarizer Filter
The first 6 filters (all but the ND1000/ND2000) have a polarizing effect. The first is pure polarizer but the rest are a combination of polarizer and ND filters. But what does the polarizer filter do?
As well as reducing a small amount of light, the polarizer filter also reduces reflections from surfaces. Surfaces such as windows, grass, leaves, still water and even water particles in the sky. Check out the difference below.
Image of Car Windscreen NO Polariser Filter
Image of Car Windscreen WITH Polariser Filter
That is the effect that a polariser filter has on glass, the effect is different in nature. The polariser filter, by reducing reflections, allows the natural colour saturation to really "pop"!
Aerial Photo With NO Polariser Filter
Aerial Photo WITH Polariser Filter
The only trade off when using a polarizer filter at certain angles and with a wide angles lens, is the darkening effect in the central part of the image. Such as in the sky above. This can easily be rectified in post but just be aware and try to change angles if possible.
How to Use the Freewell ND Filters with the Mavic 3
You will get used to it over time but each filter should be used for different lighting conditions. For example, in relatively dull conditions, you may only need a N4 or ND8 filter.
However, in bright sunlight, you will need a stronger ND filter such as the ND32 or even ND64.
The best practice is to:
Step 1. Weather Conditions
Assess the weather to see if it is heavily overcast, dulled sunshine by "wispy" clouds or bright sunlight. For each of these, choose the ND4, ND16 or ND32 respectively.
Step 2. Start and Set Up the Drone
Start your drone as usual and place it in the general direction that you will will flying and filming/photographing.
Step 3. Put the Relevant Filter on the Camera
Put your selected filter on the camera by first gently twisting and removing the existing filter. Push in slightly whilst holding the camera and turn anti-clockwise. Then, do the opposite to put the ND filter on. Align it with the holes in the camera, push in gently and twist clockwise.
Step 4. Check the Screen for Exposure
Now that the filter is on and camera facing the flight destination, check the app screen. Is the image looking well exposed? Can you adjust the aperture (between f2.8 and f5.6/f8 to correct? If it is still too bright, repeat step 3 but use a stronger ND filter. If too dark, replace with a weaker filter.
Step 5. Set the Polarizer Filter
Finally, hold the camera in place and turn the polarizer filter until you get the desired effect. Watch the app screen as you twist and stop at the point where the filter looks effective with nicely saturated colours. Fly and have fun!
How to Use the Freewell ND1000 and ND2000 Filters
This is slightly different due to the amount of light reduction. You would use these filters for long exposures like you saw in the video at the top of this page. However, you must take care.
Place the filter on the camera as described above and look at the screen. It may well be too dark to fly safely and please don't always rely on line of sight. You may be flying at greater distances.
If it is too dark, open the aperture to f2.8 on the Mavic 3 (or other drone/camera) and increase the ISO until you can see clearly in the app. This will give you enough "temporary" light to enable you to fly safely to the point of interest.
Once there, set the ISO back to ISO100 and set the desired aperture. You will then need to adjust the shutter speed accordingly and start playing. Practice until you get a slow enough shutter speed for the desired effect (milky water for example) but good enough for minimal camera shake. Have fun : )
Yes, lower ND's are generally just for video. They have no benefit for stills unless you need much slower shutter speeds. That's when you'd use the stronger ones such as the ND1000 and ND2000.
Open the aperture and ramp up the ISO to brighten the exposure whilst flying to the scene. Once there & with the shot set up, adjust accordingly. Try to set the ISO to as close to 100 as possible for best results once shooting.
I can't really compare these to the DJI sets as the Freewell filters are a combination of polariser and ND filters whereas the DJI ones are just ND filters. However, DJI make drones whereas companies like Freewell specialise in these filters. Therefore, I would say Freewell's are more than likely the better option.
Freewell ND Filters - Conclusion:
I have bought and used Freewell ND filters for my DJI Mavic Air 2 and Panasonic S1H. The quality is superb all round with regards to colour representation, clarity and sharpness retention. For filming in most daylight conditions, you will need ND filters anyway and the built-in polarizers are a bonus.
I find these filters a pleasure to use. They come in a nice, robust and protective case and for me, the price is worth it for what they do. Whichever drone you fly, whether the DJI Mavic 3, DJI Air 2s or DJI Mini 2, grab a set of these filters and get creative with them!