Canon rf 28 70mm f 2 8 is stm vs sigma 18 50mm f 2 8 dc dn contemporary?

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From Canon RF 28-70mm f/2.8 IS STM: Canon RF 28-70mm f/2.8 IS STM: A zoom lens by Canon for Full frame cameras, 28-70mm f/2.8. Specs - Maker: Canon - Focal length: 28-70mm (zoom) - Maximum aperture: f/2.8 - Made for: Full frame sensors - Mounts: Canon RF - Stabilised: yes - Autofocus: yes What it frames like - On full frame (Canon RF): as marked, 28-70mm. - On APS-C (Canon) (Canon RF): like 45-112mm on full frame; f/2.8 gives about the depth of ...

From Sigma 18-50mm f/2.8 DC DN Contemporary: Sigma 18-50mm f/2.8 DC DN Contemporary: A zoom lens by Sigma for APS-C cameras, 18-50mm f/2.8. A tiny constant f/2.8 standard zoom: the best upgrade from a kit lens on APS-C. Specs - Maker: Sigma - Focal length: 18-50mm (zoom) - Maximum aperture: f/2.8 - Made for: APS-C sensors - Mounts: Sony E, Fujifilm X, L-Mount, Canon RF - Stabilised: no - Autofocus: yes What it frames like - On APS-C (Sony E, Fujifilm X, L-Mount): ...

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