I tested the K&F Concept filters on a Canon EOS 5D Mark III with a Canon lens.
I am very satisfied.

The filters are very well made. They are delivered well packaged. It is also practical that you get them right away in a well-padded bag and can thus store them well protected in the photo backpack. So the filters can also get no scratches and you always have the filters of one size together.

Also supplied is a cleaning brush.

The filters are absolutely accurate fit. This is not self-evident for filters of this price category.
I received the filters on a test basis which has no influence on my rating.

Original photos

Its perfect for my Canon EOS M6 mark II with the 22mm lens and the Canonb EOS RP with the 35mm lens ... I was amazed from the quality and the compact size ...

I got the filter for my EOS 750D with 18-55mm lens. The 58mm variant easily fits on top of the lens. In a direct comparison with 2 pictures of the same motif you can definitely see a difference. The dark areas are more diffuse, only slightly, but the difference is visible. Beautiful effects can be conjured up with the filter lens.

Works as promised.

These lens filters look good on my Canon EOS 200D. Contrary to other reviews, they can also be unscrewed again. The front part of the lens is movable, so you can twist the "half face" into the right position. A clear buy recommendation for the price.

I bought the M42 lens to use with Canon EOS.
I could use it without any problems!

Processing is good and the picture quality is good.
Inexpensive adapter (with lens) that also works.
Tested on EOS 450 and 80D

With regard to the adapters from various manufacturers, which were often not exactly positive and the mostly positive voices about this product, I was very curious how the adapter would interact with my old lenses and the EOS 600 D from Canon.
I tested the adapter with old original Canon lenses:

1. Macro lens 35mm - Various plant motifs were photographed and the result was impressive. The objects to be photographed were also displayed on the camera's fold-out screen. In some cases, however, I had the impression that the light sensitivity setting was not reproduced faithfully on the screen. But after I experimented a bit with it, it worked satisfactorily.
2. Zoom lens 70 - 210 mm - The zoom lens can be focused without any problems even with the largest zoom factor (which has been criticized with many other adapters. The images in the viewfinder are displayed correctly on the camera screen. And the resulting images are flawless.

The The adapter itself can be easily attached to the camera and does not come loose when changing the lens. The two lenses used could also be attached to the adapter without any problems and are firmly in place.

Overall I am totally satisfied with the adapter. I do not know if a professional would do the same would see, but for me the resulting images are really good, especially when you consider how much money you save by using the old lenses.