Optical cement. Traditionally, Canadian Balsam would have been used, but there are newer adhesives that are apparently easier. I bet UV cured is a lot more prac

Optical cement. Traditionally, Canadian Balsam would have been used, but there are newer adhesives that are apparently easier. I bet UV cured is a lot more practical in a production setting. See this article about using balsam to repair a doublet: http://forum.mflenses.com/re-cementing-doublet-elements-with-canadian-balsam-t34467.html http://forum.mflenses.com/re-cementing-doublet-elements-with...