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50mm Zeiss SF --- When??!
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<blockquote data-quote="Binastro" data-source="post: 3476749" data-attributes="member: 111403"><p>I hope that Gijs doesn't mind.</p><p></p><p>But</p><p></p><p>Dr Gijs van Ginkel</p><p>Investigation of top quality telescopes.</p><p>2009.</p><p></p><p>He confirms, as I well know, that calcium fluorite is affected by humid air.</p><p></p><p>That is why such elements, not only have to coated and placed in between other elements, but also sealed properly.</p><p></p><p>If badly treated or used by the seaside, I wouldn't buy an old instrument containing calcium fluoride and I would check any instrument with exotic glass.</p><p></p><p>As an aside my 52cm Newtonian mirror lost all its new coating one week from new because I backed my classic Saab without catalyser into the garage, where the exhaust gases went into the scope bottom end where the mirror was situated.</p><p></p><p>One week..</p></blockquote><p></p>
[QUOTE="Binastro, post: 3476749, member: 111403"] I hope that Gijs doesn't mind. But Dr Gijs van Ginkel Investigation of top quality telescopes. 2009. He confirms, as I well know, that calcium fluorite is affected by humid air. That is why such elements, not only have to coated and placed in between other elements, but also sealed properly. If badly treated or used by the seaside, I wouldn't buy an old instrument containing calcium fluoride and I would check any instrument with exotic glass. As an aside my 52cm Newtonian mirror lost all its new coating one week from new because I backed my classic Saab without catalyser into the garage, where the exhaust gases went into the scope bottom end where the mirror was situated. One week.. [/QUOTE]
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50mm Zeiss SF --- When??!
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