While Sigma launched its first Canon RF (or RF ... with the announcement of the Canon RF-S 3.9mm f/3.5 STM Dual Fisheye lens.

along with a dual fisheye lens for VR or spatial capture, though users can also use Canon's full-frame RF-mount lenses on its APS-C cameras. The four Sigma F1.4 DC DN prime lenses join two F2.8 ...

You can't expect the same performance from a superzoom lens like the Sigma 18-300mm F3.5-6.3 DC Macro OS HSM Contemporary ($579) as you can from a prime lens or a shorter high-quality zoom like ...