<?xml version="1.0" encoding="utf-8"?>
<rss version="2.0" xmlns:dc="http://purl.org/dc/elements/1.1/" xmlns:atom="http://www.w3.org/2005/Atom">
	<channel>
		<title></title>
		<description>Diskussion </description>
		<link>http://r2.astro-foren.com</link>
		<lastBuildDate>Wed, 08 Apr 2026 01:00:57 +0200</lastBuildDate>
		<generator>JComments</generator>
		<atom:link href="http://r2.astro-foren.com/index.php/de/component/jcomments/feed/com_content/405" rel="self" type="application/rss+xml" />
		<item>
			<title>Alistair Gutcher schreibt:</title>
			<link>http://r2.astro-foren.com#comment-92</link>
			<description><![CDATA[Hi, I notice that the dominant problem in the several examples of Vixen VC200L tested here is the Spherical Aberration. If you alter the mirror spacing (move primary or secondary away / towards each other), the Spherical correction will change. Did you in each and every case alter the mirror spacing until you found the spacing that gave you the minimum Spherical Aberration? If you didn't then this invalidates your Strehl testing unfortunately! At least since the system has an (I assume) Spherical secondary mirror, it should be relatively insensitive to secondary decentering causing Astigmatism, thus so as long as you collimated well at for example 500x magnification, then the Astigmatism found here is it seems ground into the optics and is very disappointing.]]></description>
			<dc:creator>Alistair Gutcher</dc:creator>
			<pubDate>Tue, 12 Jan 2016 04:46:47 +0100</pubDate>
			<guid>http://r2.astro-foren.com#comment-92</guid>
		</item>
	</channel>
</rss>
