Lens review

Pentax smc DA 17-70 mm f/4.0 AL [IF] SDM

5. Chromatic aberration

In this category, Sigma 17-70 mm and the new Pentax kit lens raise the standards quite a lot. Sigma gave a medium aberration level only wide open and at focal lengths range ends ( 0.10-0.11%) and in the other cases the level was low or imperceptible. The kit lens performed alike. The 30-55 mm range gave us imperceptible aberration level, less than 0.05%. Only at the shortest focal length and on significant stopping down the aberration increased to a medium level.

It is our pleasure to inform you that the Pentax 17-70 mm doesn’t stand out from its competitors here. At 30-70 mm the aberration level doesn’t bother us at all. Like with the kit lens it doesn’t exceed the 0.05% value, very small in itself. The biggest chances to see the aberration at all are at 17 mm focal length, where its level increases from about 0.12% wide open (and here it can be a bit of a problem) to 0.09% by f/22. These are still medium values although sometimes they border the high level, but, all in all, we shouldn’t complain. Pentax deserves our recognition for producing a lens that combines the wide focal lengths range and a sensible aberration correction system.