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Chromatic aberration, also known as color fringing, is a common problem with high-resolution digital SLRs, even when using professional-caliber lenses, which were never designed for the precision required by cameras such as the Nikon D2X, and Canon EOS 1Ds Mark II. Color fringing is usually seen as red or cyan-colored edges, especially noticeable along high contrast areas (blue/yellow fringing is less common, and less obvious). This will be obvious in the examples shown further on in this article. Nikon Capture 4.3 and later offers a very effective Color Aberration Control (CAC) feature which is easy to use—simply enable it. There is no guesswork involved as with the red-cyan and blue-yellow sliders as found in Adobe Camera Raw. Shown below are the global preferences to enable or disable CAC, and the per-image preference to override that setting:
CAC even offers benefits when using shift lenses fully shifted, though it does not fully eliminate color fringing in a frame taken with a shifted shift lens. Does this feature give Nikon Capture an “unfair” advantage when comparing it to other raw converters? Without a doubt it’s an advantage, but it’s hardly unfair—it’s simply one of the advantages of using Nikon Capture. Sharpening on all images on this page was done in Adobe Photoshop on the luminance (L) channel in Lab mode, which avoids any color artifacts due to sharpening in RGB. We show both resolution chart shots and field shots of various kinds, with a variety of lenses. The examples were chosen not for examples of fine photography (which they are not), but as good “demo” examples. Clicking on a link below will open each example on its own page, or you can read this page sequentially. Resolution Chart—Nikon
60mm/f2.8D Micro Nikkor
The 60mm/f2.8D Micro-Nikkor is one of the sharpest lenses available for the Nikon D2X, at least when shot at relatively close distances. It has very little color fringing. Let us see how Color Aberration Control (CAC) performs with such a lens, and whether it makes a difference. The crops shown below are actual pixels from the 3 X 2 foot Charles Sleicher resolution chart, so focus was close, but not macro range.
The old 20mm/f3.5 AIS Nikkor is a sharp lens, but it has strong color fringing. Let’s see how CAC works its magic (extreme corner only).
The 24mm/f2 AIS Nikkor is a sharp lens, but it has strong color fringing. Can this old workhorse be resurrected using Color Aberration Control? Here’s a horizontal crop of the full frame-width. We’ll look at the section at the lower left.
This building stood still long enough to be photographed, though it fell over shortly after being photographed (just kidding, but you never know in California). The Nikon 12-24DX is a good to excellent lens, with good control of color fringing until the edges and corners are reached. But like the 10.5mm/f2.8DX, color fringing in the corners can be quite strong. Examine the three crops below, indicated by the red rectangles, and you’ll see that CAC has eliminated the color fringing—really an excellent result. It can’t add the sharpness one wishes were present in the 12-24DX, but it does restore what sharpness is available.
We’ll examine 3 crops from the image below as indicated by the red rectangles:
Schneider 28mm/f2.8 PC Super Angulon Now for the “acid test”—a shift lens. It is no easy task for the software to correct color fringing without being “told” that the optical center of the lens is not in the center of the frame! Let’s see how CAC handles its job on a shifted frame and the unshifted frame, and whether there is any difference between the two for the same portion of the image. Shown below are the left frame (lens shifted 11mm), and the center frame. The image has been cropped vertically; a large part of the foreground and a small part of the sky has been removed.
First, let’s take a look at the leftmost crop. This is an extreme shift of 11mm. (None of the actual pixels crops below have been sharpened).
Now let’s examine the bench, which is in the middle of the left frame (edge of the center frame).
Examining the same portion of the image, but taken from the center frame:
Let’s see if the effect is consistent. The lights are directly above the bench.
Nikon Capture’s Color Aberration Control (CAC) feature is highly effective at reducing or even eliminating chromatic aberration. Its use could not be any simpler: simply enable it with no further user input required. The only area in which CAC is not completely effective is with shift lenses, where shifted frames are only partially corrected. However, no portion of the frame worsens, so the feature may be safely used with no fear of improving image quality in one area while degrading it in another. If you’re shooting RAW format images on a Nikon body, and willing to use Nikon Capture for processing your images, you can ignore the issue of chromatic aberration. This means that many old Nikkor manual-focus lenses, which may have strong color fringing, just got an “upgrade” to their optical performance. Of course, even some modern lenses have color fringing, so they also benefit. Kudos to Nikon for providing this outstanding feature.
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