I thought this would be of interest to some PDMLers.
Today, I was trying to shoot (with a camera) a couple of (I think)
vultures sitting on the top of an dry old tree.
Because the rest of the frame was filled with the sky, the background was
very bright, despite the fact that it was cloudy. So, essentially
it was a contra-light setting.
I had to dial +3 EV compensation to bring the black birds from the
darkness of the "shadow".
When I put the SMC F x1.7 AF converter in front of the 60-250 lens,
it produced well pronounced purple fringing, while it was either
absent or much more subtle without the converter.
I haven't looked at the actual photo on a computer screen, but on the
camera preview, it looked like it was several pixels wide.
This, in a way, confirms my guess about the origin of the purple fringing,
in the way that you need a large gradient over a huge brightness
difference (several EVs) to be present:
http://pdml.net/pipermail/pdml_pdml.net/2014-October/386316.html
Igor
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