Ever since I switched from Canon DSLR to Fuji mirrorless, I have been unsure about what to do with my Canon gear. I invested so much in this brand, but the 5D Mark II was just not working anymore for my purposes, especially in low light and long exposure projects. I decided to order the auto focus mount adaptor from K&F and honestly did not have high expectations. These adaptors often don't fit precisely and are sometimes very hard to remove or install.
Well, today I took ALL of my Canon lenses out for a trip to test them with the adaptor on my Fuji X-t5. I am very impressed.
I used a wide angle, a medium wide-angle to medium close-up and the reason for buying the adaptor: my 200mm with 2x extender. The attached picture is taken out of hand at 400mm (200 with 2x extender) and it did a great job. It does even better on a tripod at this focal length but this bird was the true test, as it was not something I could prepare for. Had I come in with a tripod, it would have left. Now, all I did was lean against a tree for some basic support and this is what I got. This is a cropped and regularly sharpened image.
The miracle of this adaptor, that feel sturdy and has a smooth fit to the camera, is that it play really well with the Fuji body. I have full control over aperture and speed, I can use exposure correction and achieving focus was certainly acceptable. There were some situations where there was less contrast and it took a bit longer. But that is totally acceptable.
So, this is a good value for your buck - not just because it works as advertised, but mainly because it saves you a ton of dollars because there is no need to invest in a Fuji lens. My Canon gear now has retrieved its original value and more, because the Fuji body is such a top notch camera for my purposes.

This review is written right after buying the product. So if I find out that in time it operates less well, I will come back with a new review. For now I am very happy!

Seems very solid, autofocus works quickly and reliably on my XT30ii with Sigma 18-35. I can recommend it - especially for the price.

I have the AF version of the Canon EF-Fuji X adapter. Well -made with both mounts made of metal - unlike some of the competition. I use it only on my Canon EF400 f5.6 mounted on my Fuji X-T4 and X-H2S and it performs well, in fact I reckon the X-T4 has the edge surprisingly. IBIS doesn't appear to work however there is a mention in the instructions that IBIS works only with lenses of 100mm or less so that's that. The AF is quite fast and accurate as long as the available light is reasonable but to be fair any stuttering is then the fault of the lens and not this adapter. Aperture can be changed on the camera depending on camera mode settings. A proper read of the included instructions is necessary having the recommended camera settings make a big difference to the performance of the adapter.
Not the cheapest adapter yet certainly not the most expensive either and it enables me to use a 400mm high quality prime telephoto lens at a budget price.

Aus meiner (D)SLR-Zeit liegen bei mir in der Vitrine noch einige Canon EF-Objektive, u. a. EF 70-200 mm F2,8 L, EF 100-400 mm F4,5-5,6 IS L und EF 300 mm F4 IS L. Den Scherben ist ihre langjährige Nutzung anzusehen, sind aber optisch in einwandfreiem Zustand. Problem: Ich fotografiere aktuell mit Fujifilm X - Kameras, darunter auch X-H2. Die Frage war liegen lassen oder nutzen. Eine Option war der K&F Concept Adapter. Für den Adapter waren keine funktionalen Einschränkungen abgegeben. Der erste Bestellversuch beim Hersteller in China scheiterte, war dort nicht mehr lieferbar. Der Adapter war aber über Amazon beschaffbar, kam aber mit einem Tag Verspätung.

Zum Adapter: Das Teil wurde sicher Verpackt in einer Schachtel zusammen mit einem USB-Kabel und einem Sechskantschlüssel geliefert. Mechanisch klappt die Kopplung sowohl zum Gehäuse als auch zu den Objektiven hin ohne viel Kraftaufwand. Ein größeres Spiel zwischen den Bauteilen ist bei meinem Adapter nicht erkennbar. Die Objektive sitzen fest. Der Stativadapter ist abnehmbar, mich stört er, da die Objektive alle eigene Objektivschellen haben.

Bei allen Objektiven habe ich bei Tests keine erkennbaren Funktionseinschränkungen feststellen können (Fujifilm X-H2 Firmware 3.10). Der Autofokus ist (gefühlt) etwas langsam, sitzt aber dort, wo er soll. Auffällige Probleme mit der Bildstabilisierung hatte ich keine. Was der Adapter letztendlich bringt, wird die Praxis zeigen.

Wirkt sehr solide, Autofokus funktionert auf meiner XT30ii mit Sigma 18-35 flott und zuverlässig. Kann ich empfehlen - vor allem für den Preis.

I have four Canon lenses that I didn’t want to be obsolete, so this electronic adapter was a must.

It is solid and sturdy, but keep in mind that it’s certainly not as quick and efficient as Canon lenses in their native environment, so don’t think it’s going to be flawless.

Having said that, I am extremely happy with the 98% or so efficiency that I’m getting with this device and I’m getting to use my Canon lenses on my Fuji, which is the whole point.

I would definitely buy this adapter again.

The adapter seems well made and fits perfectly on my camera. I have found a bit of an issue that requires father experimentation... when I used my Canon 18-200 lens with the adapter to shoot some buildings, the images were a bit distorted, for example a flat roof came out a bit wavy. The auto-focus works so-so, sometimes it takes quite a bit of "zooming" before it lands on the correct focus. Once it does focus, the resulting images are sharp.

also works with the older Tamron zoom.

Struggles in low light, lenses sound louder when trying to focus and focus slower. Works as you would expect of a 3rd party adapter no serious issues with it

Betrayed by the age and weight of the bodies and lenses, I bought a lighter and more modern Sony body. The Canon 28-105 USM was a faithful companion, so I can keep it thanks to this adaptor ring.