>>3518844>Camera Raw>Lens correction>Chromatic abberationIf trying to resolve after the fact.
Otherwise set up your camera on a tripod, take the same -exact- photo each time. Try to shoot something that often shows obvious fringing issues, like tree branches. Start wide open, take a photo, close down a stop, take a photo, etc. till you've gone through every aperture. Open on your computer and see which has the least fringing. On most lenses your best apertures (sharpest, fewest aberrations, least distortion, least diffraction) will be right around the middle. Try to shoot around whatever aperture is the best on your lens.
If none of the apertures look particularly great, you have a crappy lens. Get a sharp prime. $200 on a 50mm prime will serve you much, much better than the $500 zooms most gearfags are running around with. Zoom lenses do not have good optics unless you pay big big bucks.
