Archived posting to the Leica Users Group, 2006/07/06
[Author Prev] [Author Next] [Thread Prev] [Thread Next] [Author Index] [Topic Index] [Home] [Search]Folks - As promised, here's an example of a disturbing symptom I encounter occasionally with the 400 Telyt. Here's a snap of a blue heron impersonating a stick: http://gallery.leica-users.org/album409/Camoflage_Heron_Crop And here's a 100% pixel crop showing heavy purple fringing around the feet and along the top edge of the log (in areas of serious overexposure): http://gallery.leica-users.org/album409/Camoflage_Heron_PurpleCrop I've seen the same effect on Kodachrome, so I don't think it's one of those artifacts of digital sensor architecture (despite all the talk you hear about purple fringing in digicams.) My questions are as follows: 1. Is this just a classic case of chromatic aberration in a simple achromat? (I hear tell that the Anomalous Dispersion glass (whatever that is) in this design is supposed to control this kindof thing to a pretty acceptable level.) 2. If so, is it really possible that the results in the normally exposed areas can look as good as they do (not that this snap is the best example; things were getting pretty dim at the time and the shutter speed was probably quite low) with a level of CA this high? 3. Does someone who uses both this lens and the probably staggeringly CA-free 280 APO (Doug??) ever see this effect in their 400 shots and not in those shot with the APO ? Inquiring minds want to know... Bob Palmieri