In my test, no brick walls were photographed, 100% cropped in the corners, or pixel peeping was done. It is a diagonal fisheye, so there are no spherical images as with circular fisheye. The 180° picture angle is therefore only available in the picture diagonal. The K&F Concept 2.8/11 was simply attached to the Nikon Z 6II and photographed with it, then evaluated purely subjectively. K&F Concept is a Chinese company that manufactures lenses. When you think of Made in China and a Chinese company, you think oh dear, here comes a lucky bag. You think they can do something, prejudice is such a thing, completely unfounded here. How much of what we have in our hands comes from China, since many companies have outsourced their production to Asia. But I've also experienced completely different things, but also with the top dogs themselves. The lens is milled from the whole, pure metal housing, real coated optical glasses of the finest quality and at a great price. The lens is well calculated, at least for the price range and a diagonal fisheye. If you think you can get more from the top dogs for 5 - 10 times the price, you should try it. Sharp right into the corners and that from aperture 4.0, minimal weaknesses at 2.8, but this is to be expected with a UWW fisheye, nothing dramatic. With a UWW simply set to aperture 4 or even better 5.6 and everything is sharp from front to back. Close-up limit is 17cm. The lens cover is also made of full metal and perfectly protects the curved front lens. The front lens is so curved that no filters can be used, as with almost all Fisheye. It is also a purely manual lens with no electronic contacts or data transmission whatsoever. The whole thing weighs 512gr. without lid (weighed on precision scales), in the Nikon Z variant, but is still small and compact. Fits perfectly to the Nikon Z6II and is super balanced. Working with the lens on the Z 6II is great fun. You can adjust the aperture wonderfully (absolutely smoothly without a grid), read the sharpness range on a scale (where else does that exist today). It comes with a front and back cover, a guarantee card/instruction manual (who needs them) in the finest Chinese writing, and anyone expecting anything else is out of place here. The whole thing in a small, white box, absolutely shockproof, embedded in two Styrofoam shells. The bayonet connection is also made of metal, just like the permanently installed lens hood. The image look is a bit like slides or paintings, you have to like it, that's the character of this lens. The entire lens looks a bit like from days gone by in terms of its optics and feel (all metal). But it is a price-performance hit and can be used as a fisheye, UWW & panorama wide angle if you know how to use it properly. The advantage of a diagonal fisheye, when used correctly, you can also achieve straight lines. It is very suitable for architecture, see the picture of the side view of the church. When looking at the side view of the church, I was surprised how well this works. I give 5 stars because for this price and in this quality there is nothing better to get at the moment, above all the image quality and the versatility of this lens are convincing. That's the most important thing in a lens. You can't go wrong here.