On 1 Nov 2004 at 11:01, Joseph Tainter wrote: > Of what is it composed? I understand that it used to include calcium > fluorite, but apparently that stuff caused other problems and something > else is used now. Anyone know?
I don't know what glass formulations Pentax used in it's ED elements however I doubt that they would have been fluorite based as use of this material was pretty much the domain of Canon. It was difficult to implement flourite lenses but I don't remember if it oxidized or was hydroscopic. Interesting page that cites the RI of materials that you would not normally associate with optics: http://www.harricksci.com/H_optics.cfm Rob Studdert HURSTVILLE AUSTRALIA Tel +61-2-9554-4110 UTC(GMT) +10 Hours [EMAIL PROTECTED] http://members.ozemail.com.au/~distudio/publications/ Pentax user since 1986, PDMLer since 1998
