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  1. rcabrerab90

    Gonio lenses... Volk vs OI

    Hello, I'm new to this forum... I was looking to buy a pair of gonio lenses, one 3-mirror lens and either a 4-mirror or a 6-mirror lens. I just have a few questions I hope someone can help me with: First of all, for the 3-mirror lens, should I get flange, no flange, nmr or what? And also what...