I received the K&F CONCEPT Gold Diffusion Filter as a test product through the Vine program and use it with various lenses, but primarily with the Sigma 24-70 Art.

I attach it when I need the digital image from the lens to be a bit softer and less contrasty. This diffusion filter is perfect for that. At 1/4, it's relatively strong (1/8 would have been preferable), but when the filter is on the lens, a cinematic quality immediately emerges.

The image becomes softer, less contrasty, and takes on a yellowish-golden sheen. However, the color temperature isn't significantly altered; it remains true to color. It's truly beautiful, as you can see in the image. A subtle halo of light appears around the edges, giving it a silky-smooth, dreamy look.

The build quality is excellent. Everything is made of metal, and the threads fit smoothly into the lens mount, even if the lens itself is plastic. It's also very thin, and even with wide-angle lenses like my 16-35mm, there's no vignetting. The glass itself is hardened, and you can clearly see the applied gold pattern.

You can screw on additional filters, such as an ND filter, to this K&F filter, making it a great all-around choice if you want this look. It also protects the lens glass.

I'm very happy with the K&F CONCEPT Gold Diffusion Filter and like to use it for shots that aren't meant to be so digital and high-contrast. Aside from a more subtle 1/8" version, I have no other wishes. Highly recommended.