This filter has a fairly large size when compared to the original lens guard that comes with the Go Ultra. The effect that that you get with this filter is great. The black diffusion filter gives you a blooming effect on highlights and it also softens the overall look of the image for the cinematic look that i prefer. The filter is very durable as i had actually dropped it twice since having it, once on concrete and the other on ceramic tile and it has zero scratches or dents. The glass is of a good thickness and wipes clean easily with the included microfiber cloth. It functions as it should and is great to use when pairing footage from the action cam to higher end cam footage.

This filter works exactly as expected and produces a very nice, subtle bloom effect that gives footage a softer and more cinematic feel. The quality of the glass and coating seems great, and it attaches securely to the Go Ultra.

My only minor complaint is that the filter feels a bit oversized and wider than it really needs to be, but that doesn’t affect performance. The build feels solid, and the effect it gives is pleasing and professional-looking.

Overall, it’s a well-made diffusion filter that delivers the look I was hoping for.

This K&F Concept black diffusion 1/4 filter for the Insta360 GO Ultra is a useful add on if you like a softer, more cinematic look rather than the very sharp digital feel straight out of the camera. It clips on securely without adding much weight, so the camera balance and mount options remain basically unchanged. The aluminium alloy frame feels well made for such a small accessory and does not get in the way of normal operation.

In use, the 1/4 strength black mist effect is noticeable but not extreme. Highlights bloom gently around light sources, skin tones look a bit more flattering and contrast is reduced just enough to give a film like character without turning everything into a blur. For evening city shots, indoor scenes with practical lights or casual portraits, the effect suits the GO Ultra quite well.

Optically, the AGC glass and 28 layer coating hold up well. There is no obvious colour cast, and general sharpness is still acceptable for an action camera, as long as you remember that a diffusion filter is meant to soften fine detail slightly. The coatings help keep flare under control and make it easier to wipe off fingerprints, dust or light rain spots.

The main thing to remember is that this is a creative filter rather than something to leave on all the time. In very bright scenes with strong point light sources the blooming can be a bit much, and for pure action or landscape work you might prefer the clean lens look. As a compact, affordable way to add a different mood to GO Ultra footage though, it does its job well.

Attaching this filter to the camera requires a bit of care due to the small size, but the threaded mount feels secure once in place. I took it out for a spin in harsh midday sunlight and later during a night walk to test the diffusion. In bright conditions, it takes the digital edge off the footage, lowering the contrast slightly to give a softer, less clinical look. The real difference appears at night; streetlights and car headlights get a distinct, glowing halo effect that adds a lot of atmosphere to otherwise flat scenes. It manages to do this without completely destroying the sharpness of the image, which is a difficult balance to strike. The glass seems high quality and I haven't noticed any weird flaring or ghosting, even when pointing it near strong light sources. It stays firmly attached during movement, which was my main worry with such a small device. It is a specific look that won't suit every shot, but for softening skin tones or creating mood, it works very well.

Very nice “gag”;) We don't want to compare the product
with a camera Promist filter... but the effect is visible.
The lens is almost twice as large as the original - must also capture a lot more light.

Really impressed with this little filter. It softens highlights nicely and gives footage a more cinematic, dreamy look without making it blurry. The build quality feels solid and it fits perfectly on the Insta360 GO Ultra. Great value for money too. If you like that gentle “film” vibe, this is an easy upgrade to your setup.

The Black Diffusion filter impresses with its good workmanship and quality. It fits the GO Ultra very precisely and sits securely without slipping. The effects created are really impressive — they give the recordings a soft, cinematic look and pleasantly reduce harsh light reflections. Overall, a high-quality filter that significantly enhances image aesthetics.

Like all K&F Concept products, this is also of very high quality - it fits the Insta360 GO Ultra perfectly and is very useful. I find black contrast filters necessary when recording as they create a much more cinematic feel, highlight the bloom much more, and reduce contrast.

I'd definitely recommend this product.