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Message: <blockquote data-quote="Steve C" data-source="post: 1405232" data-attributes="member: 56622">Well, I don't know whether or not this deserves a new post, but since it came up here, I'll keep it here.The XD glass Vortex uses does indeed have an Abbe number greater than 90, making it a true ED glass.  The reason the Razor has better color and fringing control is because the Razor has longer focal lengths and ED works better with longer focal lengths than the Viper has in its much shorter design. The guy I talked to said it was his impression that the coatings may have indeed improved, there may have been some coating upgrades done by the factory as would be expected in the normal course of operation, but Vortex did not specify any particular change in the coatings on the Viper.  As long as the changes do not degrade the product, Vortex likely would be fine with it.FWIW.</blockquote>