[ATM] what kind of material makes up the lenses in an eyepiece?

["David Williams" <dwilliams1128@earthlink.net>]

Hello

Can you use the Schott KF4 material that was advertised just before to make up the lenses in an eyepiece?  I've heard that some of them are BK-7 and some of them are Flint glass.  Is this true?  And what kind of material is the tool that you use to grind the lens to the right curve?  Can you use a metal tool?  

Does anyone have the resources for the making of different eyepieces? (that would be helpful)

Thank you
dwilliams1128@earthlink.net
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