Tamron 20 40mm f 2 8 di iii vxd vs tamron 17 50mm f 4 di iii vxd?

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From Tamron 20-40mm f/2.8 Di III VXD: Tamron 20-40mm f/2.8 Di III VXD: A zoom lens by Tamron for Full frame cameras, 20-40mm f/2.8. Specs - Maker: Tamron - Focal length: 20-40mm (zoom) - Maximum aperture: f/2.8 - Made for: Full frame sensors - Mounts: Sony E, Nikon Z - Stabilised: no - Autofocus: yes What it frames like - On full frame (Sony E, Nikon Z): as marked, 20-40mm. - On APS-C (Sony E, Nikon Z): like 30-60mm on full frame; f/2.8 ...

From Tamron 17-50mm f/4 Di III VXD: Tamron 17-50mm f/4 Di III VXD: A zoom lens by Tamron for Full frame cameras, 17-50mm f/4. A light constant f/4 standard zoom that starts at 17mm. Specs - Maker: Tamron - Focal length: 17-50mm (zoom) - Maximum aperture: f/4 - Made for: Full frame sensors - Mounts: Sony E - Stabilised: no - Autofocus: yes What it frames like - On full frame (Sony E): as marked, 17-50mm. - On APS-C (Sony E): like 26-75mm ...

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