Compare lenses

Canon EF 200-400mm f/4L IS USM Extender 1.4x vs Sigma 120-300mm f/2.8 DG OS HSM Sports

The Canon EF 200-400mm f/4L IS USM Extender 1.4x and the Sigma 120-300mm f/2.8 DG OS HSM Sports side by side, computed from this guide's catalogue.

Which to pick

Pick the Canon EF 200-400mm f/4L IS USM Extender 1.4x if you want more reach (to 400mm equivalent). Pick the Sigma 120-300mm f/2.8 DG OS HSM Sports if you want a brighter f/2.8 (1.0 stops more light), for dim light and softer backgrounds; a wider view (from 120mm equivalent); and a fit on more cameras (39 against 22 in this guide).

Still torn? Ask the guide about the Canon EF 200-400mm f/4L IS USM Extender 1.4x and the Sigma 120-300mm f/2.8 DG OS HSM Sports

Specs side by side

Rows that differ are in full colour; the better value is marked where one is better by any measure.
Spec	Canon EF 200-400mm f/4L IS USM Extender 1.4x	Sigma 120-300mm f/2.8 DG OS HSM Sports
Maker	Canon	Sigma
Focal length	200-400mm (zoom)	120-300mm (zoom)
Full-frame equivalent	200-400mm	120-300mm
Maximum aperture	f/4	f/2.8brighter
Made for	Full frame	Full frame
Mounts	Canon EF	Canon EF, Nikon F
Stabilised	yes	yes
Autofocus	yes	yes
Zoom range	2.0×	2.5×more range
Cameras it fits	22 in this guide	39 in this guidefits more cameras

Focal range, in full-frame terms

Canon EF 200-400mm f/4L IS USM Extender 1.4x: 200-400mm.

Sigma 120-300mm f/2.8 DG OS HSM Sports: 120-300mm.

Aperture

Canon EF 200-400mm f/4L IS USM Extender 1.4x: f/4 wide open.

Sigma 120-300mm f/2.8 DG OS HSM Sports: f/2.8 wide open.

Each opening drawn to scale against f/1.4: a smaller f-number lets in more light and blurs the background more.

Field of view

How wide each sees, at each end, on the sensor it was made for.

Cameras they fit

22 cameras in this guide take both, so either works on the same body. In all, the Canon EF 200-400mm f/4L IS USM Extender 1.4x fits 22 and the Sigma 120-300mm f/2.8 DG OS HSM Sports 39.