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Mind you they had a Long Pern product there called "ED APO 120mm f/6 OTA refractor - Expected price <$3000.00 AUD" being posted for at least 12 months or more - I remember it because I was interested in the "Flourite ED" - but till now nothing has turned up either - apparently it's a WO look-alike but that's OK because Long Pern manufactures for WO I believe - FWIW
Cheers
Bill[/QUOTE]
Hi Bill,
Be careful of misleading marketing hype by some manufacturers. Fluorite is the term usually given to CaF2 lenses. This is a crystal of calcium fluorite made in a furnace and is a costly and polluting process.
ED glass has fluorite in it. But its a glass, its not fluorite. Fluorite is a crystal and is the slightly superior lens. Hence it commands a premium in camera lenses and telescope lenses.
Almost all refractors these days have 1 ED glass element. Usually its FPL53 from OHara glass in Japan. Its top notch. But fluorite is arguably better. It has less light scatter, it makes it easier for the lens maker to create a faster (lower F ratio) lens with excellent colour correction.
If you shine a green laser through a fluorite lens you will not see it. If you shine it through any other type of lens you will see it shining through the lens.
The only telescope maker I am aware of that currently offers fluorite lenses is TEC. Noone else, including Astrophysics or Takahashi.
Greg.
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