Canon ef 300mm f 4l is usm vs canon ef 400mm f 4 do is ii usm?

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From Canon EF 400mm f/4 DO IS II USM: Canon EF 400mm f/4 DO IS II USM: A prime lens by Canon for Full frame cameras, 400mm f/4. Specs - Maker: Canon - Focal length: 400mm (prime) - Maximum aperture: f/4 - Made for: Full frame sensors - Mounts: Canon EF - Stabilised: yes - Autofocus: yes What it frames like - On full frame (Canon EF): as marked, 400mm. - On APS-C (Canon) (Canon EF): like 640mm on full frame; f/4 gives about the depth of ...

From Canon EF 300mm f/4L IS USM: Canon EF 300mm f/4L IS USM: A prime lens by Canon for Full frame cameras, 300mm f/4. Specs - Maker: Canon - Focal length: 300mm (prime) - Maximum aperture: f/4 - Made for: Full frame sensors - Mounts: Canon EF - Stabilised: yes - Autofocus: yes What it frames like - On full frame (Canon EF): as marked, 300mm. - On APS-C (Canon) (Canon EF): like 480mm on full frame; f/4 gives about the depth of ...

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