Nikon 20mm f/1.8 AFS G Nikkor: Chromatic Aberration

After yesterday’s post, I got some requests about how well the new Nikon 20mm f/1.8 AFS G Nikkor lens handles chromatic aberration (CA). For the record, when I test a lens, I try not to obsess about lab benchmarks and instead focus on just using the lens. I haven’t been able to go out to use this new lens in a real situation yet, but so far I’ve seen nothing to suggest that this lens isn’t an excellent addition to the Nikkor line.

So, a quick CA test for all the pixel-peepers after the jump.

Here are 100% (1:1) views of CA, with the image captured at f/2.0. As with most lenses, CA, and light fall-off all disappear as you stop down.

Nikon 20mm f/1.8 at f/2.0 showing mild magenta fringing in Lightroom with CA removal disabled.
Nikon 20mm f/1.8 at f/2.0 showing mild magenta fringing on the right side of the frame.
The left side of the frame shows mild green fringing (CA removal disabled).
The left side of the frame shows mild green fringing (CA removal disabled).
Green fringing is eliminated when CA removal is enabled in LR5.
Green fringing is eliminated when CA removal is enabled in LR5.
With CA removal enabled in Lightroom, CA is a non-factor.
Enabling CA removal in LR5 eliminates the magenta fringe entirely.

Magenta and green fringing extends for 2-4 pixels (D810) at f/2.0. Notice that the color-fringing is only present when I disabled CA removal in Lightroom 5. Once I turned on the automatic CA removal, the color-fringing disappeared. Like light fall-off, these aberrations are really only a problem if you shoot JPEG and don’t apply any corrections to your images. For most photographers, these are non-issues, as they are corrected by a single click in your editing application. In fact, I’ve set up Lightroom to enable CA removal by default for all my cameras, something I cover in my Lightroom 5 guide.

 

3 thoughts on “Nikon 20mm f/1.8 AFS G Nikkor: Chromatic Aberration”

  1. Did you happen to notice how the coma was? I’m considering this lens for astrophotography. So far I’ve seen/read mixed comments in that regard.

  2. You already have a photo from your “Milky Way over Carhenge” article. It’s too small for me to tell but you could look at the original and see how the coma is. If it’s too much trouble, never mind.

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