Spherochromatism

/ Richard R. Barron

Here’s an example of spherochromatism, a type of chromatic aberration that is common to large-aperture lenses in the telephoto range, and is more obvious when focusing closely. This aberration is manifested by unwanted color on either side of the focal plane, usually magenta in the region closer to the lens, and green beyond the focus point. It is more obvious in images like this one…

Spherochromatism, a type of chromatic aberration, showed up rather brilliantly in this image of steam condensation I shot yesterday with my Tokina 100mm f/2.8.
Spherochromatism, a type of chromatic aberration, showed up rather brilliantly in this image of steam condensation I shot yesterday with my Tokina 100mm f/2.8.

Much of the time, images are colorful enough or complex enough visually to hide this aberration, but this image from yesterday’s pinto bean pot made it glaringly obvious.

Options? I could run the image through Photoshop or Lightroom and try the “Defringe” and/or “Remove Chromatic Aberration” features, but I tired that with this image, and it wasn’t very effective. I could grayscale the image, since color wasn’t a key aspect of this image.

As you can see, if a black-and-white rendering still expresses the scene, grayscaling works fine.
As you can see, if a black-and-white rendering still expresses the scene, grayscaling works fine.

Spherochromatism isn’t a huge problem, but it’s worth knowing about, and this example of it is quite striking.