12mm but for portraits at a desired focal of 85mm only the art can master that.

Currently have the Sigma 20, 35 & 50 mm Art Series lenses as well as the original, and much beloved 85mm.

I rented the Canon 85mm and loved it, but all of my peers pressured me to get the Sigma

If you're considering a fast 85mm, you can't go wrong with either one - but I'm quite happy with my choice.