Canon Rebel T2i Digital Camera Review$899.99
Chromatic aberration is the presence of color imperfections, caused when a camera is unable to focus different light wavelengths precisely. As was the case with last year's T1i, the T2i fared well in this department — about on par with most lenses in this price range. There were no real surprises with the testing results; chromatic aberration was most apparent at the edges of the image, when shooting at the widest angle settings.
At 18mm, the lens was sharpest at an aperture of f/9. At this focal length, the sharpness tends to be best right in the center of the lens, with gradually decreasing results further from the center. Chromatic aberration was generally worse on the edges as well; the lens turned in its poorest performance on the edges of the f/22 photos.
At 37mm, the lens demonstrated excellent sharpness at both f/4.5 and f/11. At an aperture of f/29, however, the sharpness was greatly diminished, even in the center of the image. Chromatic aberration was also worst at f/29, as you can see from the blue fringing in the crops.
The best sharpness at 55mm easily belonged to those photos taken at the f/14 aperture. Though slightly softer than the images captured at the 18mm and 37mm focal lengths, these 55mm f/14 photos are still impressively sharp. At the f/5.6 and f/36 aperture settings, the lens simply couldn't keep up. Chromatic aberration was also at its worst in these two focal lengths.
As we mentioned above, distortion was not used to calculate the T2i's resolution score: it's entirely a product of the lens, which many users will swap in and out on a regular basis. However, the kit lens of the T2i fared well compared to other cameras' kit lenses, measuring barely any distortion at the middle of the zoom range or even at the telephoto end.