Recently Adobe made available their Lightroom 4.1 Release Candidate 2 as a linked download for their customers (update available HERE). Among various bug-fixes and performance improvements, listed HERE in their blog post, one of the most important improvements to me was made to their chromatic aberration sliders, which can supposedly now correct lateral (red/green, blue/yellow fringes) and axial (purple and green fringes) aberrations, lens flare, and CCD leaking (thin purple fringes) in an image much more effectively than before.

Since I tend to use very fast primes close to wide open (namely, the 300mm f/2.8), I wanted to focus testing out the purple fringing correction–that plagues almost ALL fast primes–for myself.

Seen here is a 100% crop from an image taken with the NEX-7 and Nikon 300mm f/2.8 AI-s ED, wide open. The purple fringing is very obvious here around the white lettering on the red and black background:

Before this update, one solution I had was to simply turn down the saturation all the way in the purple channel, which worked just “okay”. You can see in the crop below that there is still fringing evident, but instead it is of a slightly different color, and the haloing is actually more obvious. With shots of purple subjects, flowers, in particular, this method would be detrimental to the output of the picture, as any purple flowers would be desaturated in the process, as well as the overall tonal range being constrained. This is evident here as well, the resulting image looks more “flat”:

However, with the new update, all that is required is to go under Develop–>Lens Corrections–>Color–>De-fringe (Purple Hue) and move the “Amount” slider around until you start to see it go away. If that doesn’t work, sliding around the hue adjustment bar to match the particular fringe’s color locks in the reduction. Afterwards, I end up with the shot seen below that is completely devoid of purple fringing, and the haloing of the reduction is a lot less obvious than in the above crop; meaning it is correctly targeting only the localized fringing, rather than affecting the entire tonal range of the picture:

So, what does this all mean?

If you are a fast prime shooter who wishes that the maximum aperture of your lens would be more useful–since generally lenses fringe noticeably wide open with large apertures–this update allows you to shoot without worry, regardless of how big your aperture gets. This is especially helpful when printing big, as it is one less quality of the lens to worry about showing up. If you have Lightroom 4, I highly recommend you give this a try and see how much it helps out your fast 50mm shots that were taken wide open. I guarantee you’ll be pleasantly surprised.

As always, have a great one guys.