I own the Sigma 14mm f/1.8 for astro. It's great! but it's a DSLR lens, and Sigma makes it for the Nikon F mount, which means they had to design their optics around a very small opening with a big flange distance. That's a big deal for fast, super-wide lenses, which benefit the most from the wide openings and short flange distances of modern mirrorless mounts. Canon could certainly make a 14mm lens one stop faster for their R mount. No doubt it would be huge, but so is the Sigma, and it's always on a tripod, anyway. BTW, the vignetting isn't ever a real-world problem for me... We've been testing the Canon 24-240 RF which has serious vignetting and distortion at 24mm, but the camera and Lightroom both automatically correct for it in post, which means you never see any problem with your images. I am fine with that.How can this be unrealistic if Tony said it is “doable”? With, let me guess, around 10 stops of vignetting in extreme corners and a bucket sized front element to the boot.