Compare lenses

Pentax HD DA 20-40mm f/2.8-4 ED Limited DC WR vs Pentax smc DA 18-55mm f/3.5-5.6 AL WR

The Pentax HD DA 20-40mm f/2.8-4 ED Limited DC WR and the Pentax smc DA 18-55mm f/3.5-5.6 AL WR 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 a brighter f/2.8 (0.6 stops more light), for dim light and softer backgrounds. Pick the Pentax smc DA 18-55mm f/3.5-5.6 AL WR if you want more reach (to 82mm equivalent), a wider view (from 27mm equivalent) and a lighter lens (235 g against 283 g).

Still torn? Ask the guide about the Pentax HD DA 20-40mm f/2.8-4 ED Limited DC WR and the Pentax smc DA 18-55mm f/3.5-5.6 AL 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 20-40mm f/2.8-4 ED Limited DC WR	Pentax smc DA 18-55mm f/3.5-5.6 AL WR
Maker	Pentax	Pentax
Focal length	20-40mm (zoom)	18-55mm (zoom)
Full-frame equivalent	30-60mm on APS-C	27-82mm on APS-C
Maximum aperture	f/2.8-4brighter	f/3.5-5.6
Made for	APS-C	APS-C
Mounts	Pentax K	Pentax K
Stabilised	no	no
Autofocus	yes	yes
Zoom range	2.0×	3.1×more range
Weight	283 g	235 glighter
Cameras it fits	20 in this guide	20 in this guide

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.

Pentax smc DA 18-55mm f/3.5-5.6 AL WR: 18-55mm on APS-C, like 27-82mm.

Aperture

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

Pentax smc DA 18-55mm f/3.5-5.6 AL WR: f/3.5 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.