> fra: "Rob Studdert" <[EMAIL PROTECTED]> > > On 25 Nov 2004 at 23:06, DagT wrote: > > > No > > > > In some cases I�ve got some CA (or purple fringing) as you can see here: > > http://www.photo.net/photodb/photo?photo_id=2478716 > > Thanks for pointing me to your example images, I assume you are pretty > pleased > with the lens?
Yes, I'm very pleased and I use it a lot, but I guess I should mention that I never use a tripod so I haven't tested just how sharp the lens is. > Also think it wise to consider CA and purple fringing to be related but not > entirely the same. For instance CA often be virtually eliminated using PS CS > RAW but a saturated fringe can still remain. The general consensus seems to > be > that this is a function of a particular sensor over-saturation phenomena > known > as bloom. > > A lot of my old E-10 images suffered this quite badly so I developed counter > measures (it should be noted that I didn't have the benefit of the easy CA > reduction that we do using PS CS RAW either). > > My method using PS was to magnify the image to a point where the whole > offending pixels could be easily viewed then using the select > colour range > tool click on the most saturated area of the bloom then side the fuzziness > slider up to 150-200. The resulting selection will generally only encompass > the > offending (often purple) bloom which can generally be de-saturated using the > hue/saturation tool rendering a far more natural image. Thanks, I'll try this next time I get that problem. In practice It only occures in cases like the tree image, were you have very high contrast and sharp structures in the corners of the image. This fits with your description of the problem. DagT
