Color fringing with Rebel XT

[Ray]

noticed something on my first processed images and wanted to see if
the was a problem with the camera, the lens or my understanding of
digital.

I shot a bright blue sky with puffy white clouds and I am getting a
thin magenta line along the break between clouds and sky in some areas.
At first I thought this was because I brightened the sky a bit using
levels but, it showed in the Raw image as well


Any suggestions would be helpful.

Also I can upload the high res image if needed

[Paul]

High contrast areas are where you notice fringing the most. It can be
removed (kind of) by using Painthsop or photoshop etc. Here are the
instructions which i cut from a website (can't recall which, damnit,
so I can't give them the credit they deserve.
------------------------------------------------
remove fringing using the Hue/Saturation/Lightness (HSL) tool. For
details see the May 2003 Graphics column (available online here),
which covered some of the hidden tricks of this under-used feature. -

Instructions for using HSL to remove purple fringing will vary
slightly between programs, but they all follow the same basic process.
Start by loading up your affected image. Now go to the HSL tool. In
Photoshop, select Image-Adjustments-Hue/Saturation. In Photoshop
Elements 2, select Enhance-Adjust Color-Hue Saturation. and in Paint
Shop Pro 8 Adjust-Hue & Saturation-Hue/Saturation/Lightness.

Here is the important step: click the blue channel. Do not adjust the
master channel. Now adjust the saturation slider to around 80 per cent
(you can fine-tune this later).

If you are using Paint Shop Pro 8, move the colour wheel slowly around
and watch the preview window. When you hit the right spot, the purple
will vanish. Fine-tune the slider for maximum effect and click OK. If
there are still traces of purple, repeat the process until you find
the other tone.

The Adobe products take guesswork out of the HSL adjustment step. When
the blue channel is selected, the eye dropper tool will become
available. Click the eyedropper on the left and use it to sample the
purple fringe in your image. You can use the colour slider at the
bottom to make finer adjustments (tip: you can also use the + and -
keys to zoom in and out of the image while the HSL window is still
open).

Finally, you may find the image needs some minor tinkering and will
probably appear a little washed out. Making fine adjustments to the
Brightness/Contrast or Levels settings will correct these problems

[birdman]

Sometimes the fringing is chromatic aberration, a problem that is common in
Canon wide angle lenses for their digital SLRs at the lower focal lengths.
I say that because every demo I have seen of how to correct chromatic
aberration using a raw converter uses images made with Canon lenses. I do
not see this much using my Nikon lenses (there are plenty of other issues
with Nikons to make up for it).
If you use raw and Photoshop the raw converter in PS has an adjustment for
trying to minimize the chromatic aberration.
Alas these adjustments will not work for purple fringing due to other
causes.

[Ray]

I thought this might help. this is all of the Exif

Also it was an easy fix in PS with the Hue Sat Sliders once I knew what
to look for. I am using PS 7 so I don't think a Raw converter is
available.

Iso Speed 400

Lens 28-70 Tokina ATK Pro - No Hood

FL 28mm

WB - Auto

Shutter Speed 1/640

Ap 13.0

Shot at about 1pm on a perfect spring type day