Sigma 50 100mm f 1 8 dc hsm art vs nikon 18 105mm f 3 5 5 6?

Here is what the site says about that.

From Sigma 50-100mm f/1.8 DC HSM Art: Sigma 50-100mm f/1.8 DC HSM Art: A zoom lens by Sigma for APS-C cameras, 50-100mm f/1.8. A constant f/1.8 telephoto zoom for APS-C DSLRs, the partner to the 18-35mm f/1.8. Specs - Maker: Sigma - Focal length: 50-100mm (zoom) - Maximum aperture: f/1.8 - Made for: APS-C sensors - Mounts: Canon EF, Nikon F - Stabilised: no - Autofocus: yes What it frames like - On APS-C (Nikon F): like 75-150mm on full frame; f/1.8 gives ...

From Sigma 18-35mm f/1.8 DC HSM Art: Sigma 18-35mm f/1.8 DC HSM Art: A zoom lens by Sigma for APS-C cameras, 18-35mm f/1.8.

Quoted from this site's pages.