In this video I put the Brightin Star 9mm f/5.6 rectilinear ultra wide through real-world testing on my Canon EOS R6 Mark II (RF mount). First impressions: it shows up in a really nice box, the lens is fully manual, and the build is legit—all metal, even the rear mount, with a solid metal cap that has the right amount of pressure. Brightin Star also includes three rear filters (ND16, ND32, and a “UV” filter), and the coolest part is you can actually screw those filters onto the back of the lens, which is a big deal on a 9mm where front filters are basically impossible. Image quality is where this thing surprised me. It’s crazy wide, yet it stays rectilinear—lines are straight, and I’m not seeing barrel distortion. Sharpness is decent in the center wide open (it’s f/5.6 max, so it should behave), and it spreads pretty evenly toward the corners, though the extreme corners are still a bit soft even stopped down to f/8–f/10. Vignetting is not heavy, chromatic aberration is well controlled, and flare/ghosting is there when you shoot into bright lights, but I’ve seen much worse. For landscapes, astro, and even architecture (making small rooms look huge), this lens is just… special, and I do recommend it for what it delivers.