Pentax-DA* 50-135mm F2.8 Review

Chromatic Aberration

Chromatic aberration, commonly referred to as "fringing", is a type of optical imperfection in which the lens cannot focus the different wavelengths of incoming light onto a single point. This imperfection can be observed in images as color fringes that occur typically in high contrast edges. While theoretically, chromatic aberrations are worse in lower focal lengths, in practice, zoom lenses are most vulnerable to fringing in the shortest and longest focal lengths.

In order to test for the Pentax-DA* 50-135mm F2.8 for chromatic aberrations, we shot acontrasty scene with a bright background.

At 50mm, f/2.8:	At 135mm, f/2.8:
Click on images to enlarge

Note that these frames were taken straight from the K-5 with the chromatic aberration correction disabled.

CA Verdict

Although some fringing can be observed in the above images, we consider that this amount is not terribly intrusive in real life images. As with flare, chromatic aberration is an inherent characteristic of all lenses, and in this regards, we consider the performance of the Pentax-DA* 50-135mm F2.8 to be satisfactory. Note that effects of fringing can be reduced or corrected either by using post-processing or by correction algorithms that built-in to modern Pentax DSLR bodies.