Focal Length and Purpose
The Sigma 50-100mm f/1.8 is designed for portrait and event photography, offering a versatile mid-range zoom with exceptional sharpness. The Canon RF 100-400mm f/5.6-8 targets wildlife and sports photographers needing serious reach at an affordable price point.
Aperture Performance
Sigma's constant f/1.8 aperture throughout the zoom range is remarkable, enabling beautiful bokeh and low-light performance that rivals prime lenses. Canon's variable f/5.6-8 aperture limits low-light capability but keeps the lens compact and lightweight for its focal length.
Build Quality and Features
Both lenses feature solid construction with weather sealing. The Sigma offers HSM autofocus for Nikon bodies, while the Canon includes 5-stop image stabilization and USM focusing. The Canon's stabilization gives it an edge for handheld telephoto work.
