It appears that using Fluorite-based correction for chromatic aberration (CA) is the most effective and is considered a higher-end solution (if cost is not an issue) than ED or SuperED solutions. For your reading pleasure ... http://www.takahashiamerica.com/FluoriteAdv.htm http://clublexus.com/forums/digital-photography/321730-ed-vs-fluorite-lens-material.html http://www.birdforum.net/showthread.php?t=40468 If I understand it correctly, the main driving force for not using Fluorite-based solutions in Nikkors is cost. This seems reasonable and consistent with Nikon's corporate policy regarding mass production costs. But, my question is whether the super-teles should be the exception for this policy since they compete directly with Canon's super teles, which certainly use Fluorite, let alone Leica's APO lenses. What do you guys think? What are your opinions?