Being an SLR it's quite easy to sort out the culprit. Stick on an expensive telephoto lens and we'll see whether it's the camera that's at fault. Considering that I've never heard of it being the camera's fault and that I don't have any purple fringing, my bet is on the lens being the problem. Especially since that one is known to be bad.
http://www.fredmiranda.com/reviews/s...t=27#poststart
Even my $300 Sigma 70-300 APO shows negligible amounts of CA. My Sigma 100-300 F4 EX has none.
"We do know that is most likely to happen when apertures of greater than f/4 are used, when a wide angle of 28mm (or equivalent) or wider is used"
Being a 75-300 it was nowhere near 28 mm or under and the aperture was at F4 or smaller.