Compare lenses

Pentax HD DA 18-50mm f/4-5.6 DC WR RE vs Pentax HD DA 20-40mm f/2.8-4 ED Limited DC WR

The Pentax HD DA 18-50mm f/4-5.6 DC WR RE and the Pentax HD DA 20-40mm f/2.8-4 ED Limited DC WR side by side, computed from this guide's catalogue.

Which to pick

Pick the Pentax HD DA 18-50mm f/4-5.6 DC WR RE if you want more reach (to 75mm equivalent) and a wider view (from 27mm equivalent). Pick the Pentax HD DA 20-40mm f/2.8-4 ED Limited DC WR if you want a brighter f/2.8 (1.0 stops more light), for dim light and softer backgrounds.

Still torn? Ask the guide about the Pentax HD DA 18-50mm f/4-5.6 DC WR RE and the Pentax HD DA 20-40mm f/2.8-4 ED Limited DC WR

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 18-50mm f/4-5.6 DC WR RE	Pentax HD DA 20-40mm f/2.8-4 ED Limited DC WR
Maker	Pentax	Pentax
Focal length	18-50mm (zoom)	20-40mm (zoom)
Full-frame equivalent	27-75mm on APS-C	30-60mm on APS-C
Maximum aperture	f/4-5.6	f/2.8-4brighter
Made for	APS-C	APS-C
Mounts	Pentax K	Pentax K
Stabilised	no	no
Autofocus	yes	yes
Zoom range	2.8×more range	2.0×
Weight	not listed	283 g
Cameras it fits	20 in this guide	20 in this guide

Focal range, in full-frame terms

Pentax HD DA 18-50mm f/4-5.6 DC WR RE: 18-50mm on APS-C, like 27-75mm.

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

Aperture

Pentax HD DA 18-50mm f/4-5.6 DC WR RE: f/4 wide open.

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