Pentax 20-40mm f2.8-4.0 ED DA HD

Very good sharpness in the centre at maximum aperture, Excellent sharpness when stopped down, Very good build, Weather resistant construction, Low CA, Retro styling

Expensive for a variable aperture standard zoom, Odd zoom range is not really very wide, nor very telephoto, Neither focus or zoom are performed internally

Sharp throughout zoom range. Weather-sealed design. Compact. Metal lens barrel.

Pricey. Some distortion at the wide end. Modest zoom range.

The Pentax HD DA 20-40mm F2.8-4 ED Limited DC WR is a compact, weather-sealed zoom lens, but its range is limited and it's priced on the high side.