Pentax-DA 18-55mm F3.5-5.6 WR Review
Chromatic Aberration
"Fringing" or chromatic aberration is a type of optical distortion in which the lens is unable to focus different wavelengths of light onto a single point. Typically, this effect is most apparent on sharp high contrast edges.
In order to test the SMC Pentax-DA 18-55mm f/3.5-5.6 AL WR for chromatic aberration, we used a K-5 body with its chromatic aberration correction disabled. In order to induce a worst-case scenario, we took test shots of a test scene with a high number of high contrast edges scattered all over the frame (in this case, a wrinkled mylar sheet). Since the amount of fringing is correlated to aperture, we chose to perform the test with a wide open aperture at various focal lengths. The test images are the following (click for full size):
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| 18mm, f/3.5 |
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| 24mm, f/4 |
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| 35mm, f/4.5 |
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| 55mm, f/5.6 |
The following are some real-world test images (click for larger version):
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| 18mm, f/3.5 |
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| 55mm, f/5.6 |
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| 55mm, f/5.6 |
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| 18mm, f/3.5 |
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| 55mm, f/5.6 |
Verdict
The DA 18-55mm WR does not exhibit significant chromatic aberration when the images are viewed on screen or printed. Only when the images are inspected at 100% magnification, does the fringing become apparent. It seems to show more at the wide end of the zoom than at the long end, but the effect is not significant enough to be intrusive when the images are viewed at regular magnification. In this regards, we consider that the performance of the DA 18-55mm WR to be satisfactory.
