Questions about Sigma 8mm, f/3.5 EX DG Circular Fisheye, Canon EF

Yes, you can attach this lens to the 80D. However, note the crop factor, as this lens is a full-frame lens. (Crop factor = 1.6 for Canon) This means that the focal length would be 12.8mm on your Canon 80D.

Hello, my lens came with a SIGMA SSC warranty card.