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		<description>Diskussion </description>
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		<lastBuildDate>Thu, 16 Apr 2026 07:12:58 +0200</lastBuildDate>
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			<title>Alistair Gutcher schreibt:</title>
			<link>http://astro-foren.com#comment-217</link>
			<description><![CDATA[The optics in some of these Mewlons are disappointingly rough (as seen in your Foucalt and Lyot Phase Contrast test) compared with e.g. the Takahashi CN-212 !]]></description>
			<dc:creator>Alistair Gutcher</dc:creator>
			<pubDate>Tue, 31 Mar 2020 14:19:30 +0200</pubDate>
			<guid>http://astro-foren.com#comment-217</guid>
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			<title>Alistair Gutcher schreibt:</title>
			<link>http://astro-foren.com#comment-216</link>
			<description><![CDATA[Hi, are you saying, for this old style Mewlon 210, that you tested it's Primary mirror and it had a Conic Constant of -0.73 which is indeed Elliptical as it should be, however for the secondary mirror you get a conic constant of -0.36 ?! In which case this is a mild Ellipse and quite strongly deformed from a Spheroid, and Dall Kirkham's are supposed to have Spherical Secondary mirrors, these being easier to make, hence the attraction for Takahashi to make them in the first place and why they mention this in their Mewlon 180C user manual for example! The old style u210 user manual also says that the secondary mirror is Spherical !]]></description>
			<dc:creator>Alistair Gutcher</dc:creator>
			<pubDate>Tue, 31 Mar 2020 14:16:58 +0200</pubDate>
			<guid>http://astro-foren.com#comment-216</guid>
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