Pentax SMC PENTAX DA 17-70MM F4 AL (IF) SDM: Review

Posted to Lenses 2009-12-27

PENTAX SMC DA 17-70MM F4 AL (IF) SDM review:

The Pentax SMC PENTAX DA 17-70MM F4 AL (IF) SDM is a general-purpose zoom lens from Pentax with a 35mm equivalent focal length of 25.5 - 105mm. The lens features near-pro build quality, is constructed using 17 elements in 12 groups, and has an angle of view that ranges from a wide 79 degrees to a mid-distance 23 degrees.

The lens also features 7 diaphragm blades, a minimum focusing distance of 11 inches and SDM focusing for smoother, quieter auto focusing. The SMC Pentax DA 17-70mm has an aperture range of f4 - f22, a filter diameter of 67mm, measures 3.0" x 3.7" and weighs only 17.1 ounces. The lens has a maximum magnification of 0.31X and features the Pentax Quick Shift focus feature which allows instant switching from auto to manual focus.

Rating:

3.4 out of 5

Quality

The SMC Pentax DA 17-70mm has a very good build quality. It is constructed using extra low dispersion glass, which ensures sharper images and reduces chromatic aberration. The SDM focusing is nearly totally silent, and the focus and zoom rings have a smooth and positive feel. The lens will work with non-SDM Pentax camera bodies, but only manual focus will be available (the SDM focusing system uses the camera to drive the autofocus on the lens).

Performance

The SMC Pentax DA 17-70mm delivers very good image quality throughout the zoom range. The quality is excellent from 17-50mm, but after that becomes a little soft. Image quality overall, however, is at least as good as the comparably priced competition. Autofocus is fast and positive, although some users report that the lens tends to hunt for focus at times. The Quick Shift focus feature makes switching from auto to manual focus a snap, and the lens has a useful zoom and aperture range.

Summary

If you're in the market for a general-purpose zoom lens for your Pentax camera, the SMC Pentax DA 17-70mm makes an excellent choice. It's priced reasonably when compared to the competition, and delivers very good image quality for a lens in this price range. All in all a very good offering from Pentax.

Pros

17-70mm general-purpose zoom lens
17 elements in 12 groups
Uses SDM autofocus system
Uses SDM autofocus system

Cons

Images a bit soft above 50mm