Removing Chromatic Aberration (Purple Fringing)?

Have you tried to use two separate chromatic aberration removal bricks, one for the left side and one for the right? Then brush the correction in locally, with different settings for the left border and the right border. You will probably need to add a separate brick for each orientation of the white wooden parts.

I don't know of any tutorials, sorry,

I'm not certain, but I'm pretty sure over-exposure amplifies chromatic aberration.

The image above certainly looks like it. Because of the high exposure value the chromatic aberration colors are more noticeable on the darker sides of the high contrast edges, where we are seeing the purple cast. The cyan on the lighter side of the edge is obscured by the overexposed white.

And it may add blooming to the high contrast edges, that will interfere with the chromatic aberration, so the automatic correction may not be perfect.

Hi Ian,

Is there a RAW file ?

The image, as you've reported, is not good.

I got something of a balance in the CA correction as shown in the attached screenshot, but "fixing" this recording is — excuse the vulgarism; I first heard this in painting class, and continue to polish its pedagogical star — stirring the turd. I use Sony equipment almost exclusively, but I don't have that lens or record JPG. It may be that the lens cannot perform well wide-open, or performs poorly when pixels are blown. Have you looked on Dyxum or Kurt Munger's site for others' experience? The other explanation to examine is that your copy of the lens is a lemon. (Is that an internationally-understood Americanism?)

Screengrab:

—Kirby

(Some additons and clarifications, 1/3/2015 18:30)

I have just about grabbed the concept of the separate "bricks" but how do you adjust the orientation?

Sorry, I was not clear. I meant, you will need different settings for the sliders, depending on the location and orientation of the edge you want to correct. The vertical widow frames are showing different color fringes from the diagonal beams of the roof. And where the beams are casting shadows, the colors are less saturated.

I adjusted the two beams of the roof above by first applying the tool to the full images and trying to adjust a part of the images perfectly. Then I brushed the adjustment onto those parts where it worked.

Now I added a second adjustment brick and tried to correct more.

You'll probably need at least four adjustment bricks to get all done.

What lens and what hole size?

The easiest way to reduce CA is to record your data with a smaller lens hole.

Was it a good exposure? It's impossible to conclude anything from the file you posted, but it looks to have significant areas of blown or near-blown pixels. I'm not certain, but I'm pretty sure over-exposure amplifies chromatic aberration.

Are you recording RAW or JPG? RAW should give you much more latitude for correcting CA.

See what you get from that lens when recording with no blown pixels and using smaller hole setting. If that is unacceptable, don't use the lens. The Sony a57 is capable of much finer recordings.

Fwiw, I'm seeing purple fringing and red fringing. They may come from different causes.

—Kirby.

it looks as though the easiest solution is to spend thousands of pounds buying perfect lenses!

Or spend hundreds of dollars on software that knows your lens and can correct it. If you are using a zoom lens with a wide rage from tele to wide angle, it will be difficult to correct the chromatic aberration completely for all ranges.

The software in your camera should include the chromatic aberration correction into the RAW development, when it is creating the JPEG. Actually, one chromatic aberration adjustment should suffice, if the lens is known or does not deviate too far from a symmetrical aberration depending on the distance to the center of the image.

I noticed in the sample image you posted, that the EXIF tag with the lens is missing. Does Aperture recognize the lens? Do you have any plug-ins installed, that could correct the aberration?

PS 🙂 : My "50" is the Sigma 50/1.4. I see little (or no) CA — certainly nothing that can't be eliminated in PP. It is a FF lens, and more expensive than the Sony DT (and infinitely more expensive than your free lens).

Even better 50mm lens are currently available in a-mount.

—Kirby.

Greetings Ian, the forum experts Leonie and Kirby have given you excellent info. But I honestly think your sony camera sensor and sony 50mm lens are really to blame withthis particular chromatic aberration problem. If you could shoot in RAW format the Aperture 3.6 CA bricks will work far more effectively than on your camera jpeg files. Likewise, your 50 mm sony lens displays terrible chromatic aberration, even at a wide aperture. I use a Nikkor 50mm f/1.4D on numerous Nikon DSLR bodies and have far less CA than your lens displays even when I shoot wide open. Keep trying to master the Aperture CA bricks! Good luck.