ND Filters for DJI O4 Wide from RunCam & Flywoo – Surprising Results

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Although the new DJI O4 Wide camera is largely based on Flywoo’s Wide Angle lens for the O4 Lite camera, the original Flywoo ND filters made for that adapter do not fit the O4 Wide properly. They are slightly too loose and could potentially fall off during flight. Flywoo has now released a V2 version specifically for the DJI O4 Wide to fix this fitment issue. Around the same time, RunCam also released its own ND filters for the O4 Wide. In this review, I will compare both filter sets, how they fit, image quality, and find out which one is better.

What Does an ND Filter Do?

Without getting too technical, ND filters can be used to make your footage look more cinematic when combined with the correct camera settings. They reduce the amount of light entering the camera, allowing you to use a slower shutter speed and create more natural-looking motion blur.

If you want to understand how ND filters work in more detail, check out my tutorial: https://oscarliang.com/nd-filter-fpv/

Even if you do not care much about cinematic footage, ND or UV filters can still be useful as an extra layer of protection for the camera lens during crashes.

DJI does not sell the O4 Wide camera lens separately, so damaging the lens can become an expensive problem. Using a cheap filter as sacrificial protection can therefore make a lot of sense.

You can also learn more about the differences between UV, CPL and ND filters here: https://oscarliang.com/uv-cpl-nd-filters/

Where to Buy

You can purchase the ND filters in this review from:

Flywoo ND filters:

• Flywoo: https://flywoo.net/products/flywoo-o4…
• AliExpress: https://s.click.aliexpress.com/e/_c3jjUwg3

Runcam ND filters:

• Runcam: https://shop.runcam.com/curved-precision…
• AliExpress: https://s.click.aliexpress.com/e/_c40RBI1N

Both brands offer a complete filter set containing four filters: ND8, ND16, ND32 and UV, but RunCam is considerably cheaper:

• Runcam: $15.99
• Flywoo: $29.99

To begin with, I recommend buying the full set, especially if you are not yet sure which ND strength you will use most often.

Once you know which filter you use the most, or if you lose one, buying individual replacements can make more sense.

Unfortunately, RunCam does not currently appear to offer individual filters. Flywoo does, at around $7.99 each, which gives it an advantage if you only need to replace one.

Flywoo also includes a microfibre cleaning cloth, while RunCam does not. That might sound minor, but a cleaning cloth is genuinely useful for FPV camera filters, so I think RunCam should consider including one.

Comparing RunCam and Flywoo ND Filters

Size

I measured the filters at approximately:

• Flywoo: 18.4mm (width) x 16.5mm (height)
• Runcam: 18.6mm (width) x 14.3mm (height)

The RunCam filter is slightly wider but noticeably shorter.

Weight

The RunCam filter is about 0.1g lighter:

• Flywoo: 0.45g
• Runcam: 0.32g

The difference is negligible in practice, even on a small FPV drone.

Design and Build Quality

One of the biggest differences is probably the shape of the glass.

The Flywoo filters use traditional flat glass, while RunCam has gone for something much more unusual.

The RunCam filter uses curved glass, almost resembling a tiny ski goggle.

It certainly looks interesting.

However, the Flywoo filter feels more polished overall.

On the RunCam filters, I can see small amounts of adhesive on both edges of the lens. On the Flywoo filters, the construction looks cleaner, with no obvious glue visible.

Overall, the Flywoo filters feel slightly more premium and more refined.

Fitment

Both filters use a pinch release mechanism that allows them to snap onto and detach from the O4 Wide lens relatively quickly.

However, the mechanisms are slightly different.

Flywoo

The Flywoo filter has a single release tab at the top.

To install it:

1. Align the bottom edge of the filter with the slot in the camera lens.
2. Pinch the upper tab.
3. Push the filter onto the camera, until you hear a click.

RunCam

The RunCam filter has release tabs on both the top and bottom.

Installation is similar:

1. Align one edge with the camera lens.
2. Pinch the release mechanism.
3. Push the filter into place until it clicks.

The two-tab design makes the RunCam filter easier to remove.

You simply pinch both sides and pull it away from the camera.

The Flywoo filter takes slightly more effort to remove.

For pilots who frequently change ND filters throughout the day, I think the RunCam mechanism is slightly more convenient.

However, there is a trade off.

The Flywoo filter feels noticeably more secure once installed. Because of that, I suspect it may be slightly less likely to come loose during a hard crash.

That said, both filters stayed attached perfectly well during my testing. I repeatedly crashed my cinewhoop into a tree and could not get either filter to fall off.

Missing ND Labels on RunCam

One small but annoying drawback with the RunCam filters is that there are no markings indicating which ND strength each filter is.

If you always put them back to exactly where they belong in the box, this is fine. But if you mix them up, you may end up guessing whether you are holding the ND8, ND16 or ND32.

Flywoo clearly labels every filter, which makes them much easier to identify.

This is a small detail, but one that RunCam should really improve.

Image Quality

Both filters perform well in terms of sharpness. I could hardly see any loss of fine detail from the extra glass, even when zooming into the footage.

However, there are some noticeable differences in colour.

The Flywoo filters introduce a slightly greener tint. The RunCam filters remain much closer to the original O4 Wide image. RunCam may be ever so slightly warmer, but the difference is very subtle unless you compare the footage side by side.

Overall, I think RunCam has the more neutral colour reproduction.

This does not mean the Flywoo filters are bad. You can easily correct a mild green tint during colour grading.

I also noticed that the Runcam filters appear slightly brighter than the equivalent Flywoo filters. The difference is especially obvious with ND32, less noticeable in ND16 or ND8.

So even though both filters are labelled with the same ND rating, their actual ND strength does not appear perfectly identical.

Lens Flare

This is where the biggest difference appeared.

The RunCam ND filters produce noticeably more lens flare when the camera is pointed towards the sun or strong light source at certain angles.

The Flywoo filters perform considerably better. With Flywoo, I saw almost no obvious flare—perhaps just a tiny dot in some situations, which was hardly noticeable.

If you frequently fly towards the sun, I think the Flywoo filters have a clear advantage here.

Dark Corners

Black corners (vignetting) is quite common with ND filters on the DJI O4 Pro/Wide because these cameras have such an extremely wide field of view.

Both filters have vignetting. The RunCam filters appear to have slightly less vignetting, but the difference is small. In both cases, I would consider it very minor and not something that affects flying at all.

More importantly, you can get rid of these dark corners in your final footage anyway. When you stabilize the footage using Gyroflow or RockSteady, the image is cropped slightly, which normally removes the corners.

The same applies if you use 16:9 aspect ratio, or switch from Wide to Normal FOV. These modes crop the image enough that the dark corners generally disappear, even from your goggles’ view.

So I would not worry about these dark corners really.

My DJI O4 Wide Camera Settings

To get the most out of ND filters, you need to configure your camera settings properly.

You can leave the camera in Auto if you are mainly using the filter for lens protection, but if your goal is cinematic footage, I recommend using manual settings.

For normal daytime cinematic flying, I typically use:

• Resolution: 4K
• Frame Rate: 60fps
• Shutter: 1/120
• ISO: 100
• White Balance: 5500K
• Exposure: Manual

Locking shutter speed, ISO and white balance prevents the camera from changing them during the flight.

You can then use different ND filters to control exposure. If you use these settings without ND filter, your image will most likely be overexposed.

Keep ISO as Low as Possible

I normally keep ISO at 100, which is the lowest available value. Higher ISO amplifies the image signal but also introduces more noise. As long as you can achieve the correct exposure using the ND filter, keeping ISO low generally gives you the cleanest footage.

Fixed White Balance vs Auto

Some pilots leave White Balance on Auto. That works, but Auto White Balance can shift unexpectedly during a flight, making colour grading more difficult later.

For a sunny day, 5500K is a reasonable starting point.

A fixed value gives you consistent colours throughout the flight, and you can adjust them later in post. If you are not comfortable colour grading, leaving White Balance on Auto is perfectly acceptable too.

I have a tutorial on colour grading FPV footage here: https://oscarliang.com/color-grade-fpv-videos/

Choosing the Correct ND Filter

Once you have locked your camera settings, you need to select an ND filter that gives you a sensible exposure. You do not want the image significantly overexposed or underexposed.

A good starting point is ND16.

Check the Bright Areas

Point the camera towards a bright part of the scene, such as the sky.

Can you still clearly see details in the clouds?

Also check the exposure meter, shown as M.M. in the DJI camera interface.

As a rough guide, I generally try to keep it somewhere between:

-1 and +1

Closer to zero is preferable.

If the exposure meter is above +1, the image is probably overexposed.

You may also notice that bright areas of the sky have turned completely white with no visible detail.

In that case, switch to a stronger filter, such as:

ND16 → ND32

This should reduce exposure.

Check the Shadows

You should also check darker areas.

If shadow detail disappears and everything looks almost completely black, the image may be underexposed.

Again, check the exposure meter.

If it is below around -1, I would usually try a lighter filter.

For example:

ND16 → ND8

This allows more light into the camera.

Don’t Obsess Over Perfect Exposure

You probably will not achieve absolutely perfect exposure because you only have 3 ND strengths to choose from.

That is fine.

Simply choose the filter that gets you closest while preserving both highlights and shadow detail reasonably well.

Lighting also changes throughout a flight, especially when flying between open sunlight and shaded areas.

You are looking for the best overall compromise rather than a mathematically perfect exposure value.

Final Thoughts: Which ND Filter Is Best?

Both the RunCam and Flywoo ND filters for the DJI O4 Wide perform well, and I would be happy using either.

They both fit securely, image sharpness remains excellent, and the small amount of vignetting is unlikely to matter once your footage is stabilized.

However, each has different strengths.

The Flywoo filters feel more premium. The build quality is cleaner, every filter is clearly labelled, the attachment feels more secure, and most importantly, they show little to none lens flare. Their main drawbacks are the higher price and the slight green colour cast.

The RunCam filters are considerably cheaper and produce a more neutral image color. However, lens flare is noticeably worse when shooting towards the sun, and there are other minor downsides like the lack of ND markings on the filters, lack of cleaning cloth, etc.

For casual flying, I think RunCam offers excellent value. Just as lens protector alone is worth it.

For cinematic FPV where I want to minimize lens flare, I would favour Flywoo because the reduced lens flare is more important to me than the slight colour shift, which is easy to correct in post.

You can purchase the ND filters in this review from:

Flywoo ND filters:

• Flywoo: https://flywoo.net/products/flywoo-o4…
• AliExpress: https://s.click.aliexpress.com/e/_c3jjUwg3

Runcam ND filters:

• Runcam: https://shop.runcam.com/curved-precision…
• AliExpress: https://s.click.aliexpress.com/e/_c40RBI1N