I used to dismiss niche filters when starting out. Give me a good CPL, and a few top notch ND's and I'm good.
But over the years I have come to appreciate the things a filter like this K&F Prism can do.
I do quite a bit of post processing and I can achieve things in front of the computer that is easier to do than out in the field, but this isn't one of them.

It presents an interesting effect. Mirrored images that are seductively out of focus while maintaining good sharpness on the focused subject. The filter rotates like a CPL so the effect can be used for any angled desire.
I might be able to mimic this look with software but it would be a real pain.
I would also add that having a 'effects' filter physically attached to your lens encourages you to approach your imaging differently. As opposed to taking regular images and post processing later on. It changes your perspective, which seems like a win win to me.

It's definitely a filter I will continue to play around with...help me to approach things differently.

Thank you for taking the time to read my review.

For those who don't feel like reading through the whole thing, I'll include a pros and cons at the end.

Today I'd like to share my personal opinion on the "Linear Mirage Pentaprism Filter" from K and F Concept, which I was able to test as part of the Vine program. This doesn't influence my review in any way. I hope this can help you decide for or against the product.

The "Linear Mirage Pentaprism Filter" from K and F Concept is a surprise when you first take it out of the box. The storage box is twice as thick as other "normal" filters. When you open the plastic box, you'll understand why.

The filter is made of approximately 1.5 cm thick glass on one side and tapers from the center to the edge to approximately 0.8 cm. It weighs 76 grams. The thinner section (from halfway through the filter) is divided into four sections with varying degrees of inclination.

The filter screws easily onto the lens thread. It doesn't jam, and unscrewing it is also easy.

When taking photos with the filter, the actual subject is reflected four times from the side. You can rotate the filter like a polarizing filter to influence the direction of the reflections. The effect is very nice, and I can't detect any distortion or noticeable loss of image quality in the images.

This filter is certainly not a filter you'll use every day for your photos. However, if you want to take creative photos, this is a high-quality solution without having to use Photoshop or other image editing programs after taking the shot. Here, you can see the effect directly during the shot, and you don't have to spend a lot of time isolating the subject.

I find this filter particularly useful for colorful subjects or subjects with colored light. I would recommend it, or other similar filters.

Pros:
+ High-quality workmanship
+ Great effect
+ Solid glass filter
+ Easy-to-use thread
+ Three individually sealed microfiber cloths included

Cons:
Price for a creative filter (but justified given the quality of workmanship)

Thank you for taking the time to read my review. I hope this was helpful in your decision-making.

Best regards, Nicolas

It's a thick and heavy filter for your 82mm lens. I tested it on my Samyang 35-150 and Canon EF 16-35 F2.8III.

The base attaches by twisting like all filters, but the front still rotates to adjust the effects. It's very high-quality, both in terms of the packaging and the quality of the materials. Yes, it's expensive if you don't know what to do with it, but it's a filter that will always stay in my bag, and I'll take good care of it.

The bonus is the cleaning wipes, which are just as effective for cleaning my glasses!

This linear prism filter adds some unique effects right out of the camera. Depending on the angle, it creates colorful ghosting, foreground streaks, or split-image reflections ideal for creative portrait or product work.

It threads securely and fits standard 77mm lenses, with good optical clarity. You’ll get the best results using it in natural light with strong contrast or backlight. There’s a learning curve, but experimentation pays off.

It’s not for every shoot, but for stylized or artistic work, it delivers something special without needing post-production tricks.

A fun tool for expanding your photography kit.

This is a novelty filter. It produces some really fun and creative visual effects. I've only used it for still photography, but I think it would really shine with video/motion - as it'd be really hard to recreate this effect during editing.

I've found that a single, well defined subject works the best (vs a more generaic scene - like a landscape). Moody portraits were spot-on.

The build quality is really nice. It is a heavy duty filter. The optic quality is great (for the non-prism areas) and crisp in the prism areas. It has some weight to it. It comes in a plastic case - and also includes a few lens cloths.

If you're looking to add some creative variety to your kit, this is a good choice.

Impressive quality, very well packaged, excellent gift too. Filter prism has a high quality feel and unique properties, I will have a great deal of fun experimenting with this filter prism finding the best angle to dial it in. The value for the quality is excellent. I'm well pleased and looking forward to enhancing my photos with these magical effects and exploring new creativity as the prism can be rotated to access the different compositions of the filter. Super fast shipping

K&F Concept ya tiene su nombre en el mundillo de los accesorios de fotografía, y este filtro de pentaprisma lo he estado probando con mucha curiosidad. Transforma por completo las escenas, aportando un efecto de espejismo lineal que convierte imágenes normales en algo con un aire psicodélico y muy onírico, ideal para retratos artísticos o jugando con luces en la ciudad. Se nota que el vidrio óptico K9 es de buena calidad, mantiene los colores fieles y una alta transmisión de luz. Además, el marco se puede girar para ajustar el efecto, lo que da mucho juego, aunque requiere un poco de práctica para dominarlo bien. Que incluya tres paños de limpieza es un detalle que se agradece bastante.

This K&F Concept pentaprism filter has been a real surprise for my creative sessions. I'm using it with my Fuji GFX100RF (with a 58mm adapter) and the results are spectacular: it creates a very striking linear mirage effect, ideal for artistic portraits or urban scenes with lighting. The optical glass looks good quality, doesn't distort beyond the desired effect, and fits perfectly.

It also comes with three cleaning cloths, which is very appreciated