Compare lenses

Pentax HD DA 20-40mm f/2.8-4 ED Limited DC WR vs Sigma 17-70mm f/2.8-4 DC Macro OS HSM Contemporary

The Pentax HD DA 20-40mm f/2.8-4 ED Limited DC WR and the Sigma 17-70mm f/2.8-4 DC Macro OS HSM Contemporary side by side, computed from this guide's catalogue.

Which to pick

Pick the Pentax HD DA 20-40mm f/2.8-4 ED Limited DC WR if you want the flexibility of a zoom. Pick the Sigma 17-70mm f/2.8-4 DC Macro OS HSM Contemporary if you want optical stabilisation, which helps most on bodies without it; more reach (to 105mm equivalent); a wider view (from 26mm equivalent); and a fit on more cameras (51 against 20 in this guide).

Still torn? Ask the guide about the Pentax HD DA 20-40mm f/2.8-4 ED Limited DC WR and the Sigma 17-70mm f/2.8-4 DC Macro OS HSM Contemporary

Specs side by side

Rows that differ are in full colour; the better value is marked where one is better by any measure.
Spec	Pentax HD DA 20-40mm f/2.8-4 ED Limited DC WR	Sigma 17-70mm f/2.8-4 DC Macro OS HSM Contemporary
Maker	Pentax	Sigma
Focal length	20-40mm (zoom)	17-70mm (macro)
Full-frame equivalent	30-60mm on APS-C	26-105mm on APS-C
Maximum aperture	f/2.8-4	f/2.8-4
Made for	APS-C	APS-C
Mounts	Pentax K	Canon EF, Nikon F, Pentax K
Stabilised	no	yesstabilised
Autofocus	yes	yes
Zoom range	2.0×	4.1×more range
Weight	283 g	not listed
Cameras it fits	20 in this guide	51 in this guidefits more cameras

Focal range, in full-frame terms

Pentax HD DA 20-40mm f/2.8-4 ED Limited DC WR: 20-40mm on APS-C, like 30-60mm.

Sigma 17-70mm f/2.8-4 DC Macro OS HSM Contemporary: 17-70mm on APS-C, like 26-105mm.

Aperture

Pentax HD DA 20-40mm f/2.8-4 ED Limited DC WR: f/2.8 wide open.

Sigma 17-70mm f/2.8-4 DC Macro OS HSM Contemporary: 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

20 cameras in this guide take both, so either works on the same body. In all, the Pentax HD DA 20-40mm f/2.8-4 ED Limited DC WR fits 20 and the Sigma 17-70mm f/2.8-4 DC Macro OS HSM Contemporary 51.