Sigma 20mm f 1 4 dg hsm art vs voigtl nder nokton 21mm f 1 4 aspherical?

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From Sigma 20mm f/1.4 DG HSM Art: Sigma 20mm f/1.4 DG HSM Art: A prime lens by Sigma for Full frame cameras, 20mm f/1.4. Specs - Maker: Sigma - Focal length: 20mm (prime) - Maximum aperture: f/1.4 - Made for: Full frame sensors - Mounts: Canon EF, Nikon F, Sony E, L-Mount - Stabilised: no - Autofocus: yes What it frames like - On full frame (Canon EF, Nikon F, Sony E, L-Mount): as marked, 20mm. - On APS-C (Nikon F, Sony E, ...

From Voigtländer Nokton 21mm f/1.4 Aspherical: Voigtländer Nokton 21mm f/1.4 Aspherical: A prime lens by Voigtländer for Full frame cameras, 21mm f/1.4. Specs - Maker: Voigtländer - Focal length: 21mm (prime) - Maximum aperture: f/1.4 - Made for: Full frame sensors - Mounts: Sony E, Leica M - Stabilised: no - Autofocus: no, manual focus What it frames like - On full frame (Sony E, Leica M): as marked, 21mm. - On APS-C (Sony E): like 32mm on full frame; f/1.4 ...

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