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Collimation Again, Again, Again
Chaps,
Having now put my mirror right out and back about a thousand times i think i can say i know how to collimate it. One question i have means explaining my checking proccess: Pick a bright star and put it so far out of focus that i fill almost the whole view. If the spyder is central in the brighter area of the view collimation is correct.... Does anyone think this sounds about right? Rob |
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"Robert Geake" wrote:
Having now put my mirror right out and back about a thousand times i think i can say i know how to collimate it. One question i have means explaining my checking proccess: Pick a bright star and put it so far out of focus that i fill almost the whole view. If the spyder is central in the brighter area of the view collimation is correct.... Does anyone think this sounds about right? Sounds about right, but a bit imprecise. I've found slight defocussing at the highest magnification you can (to see the airy disk and rings) is more precise - I think that's what is usually meant when "star testing" is referred to. Tim -- Love is a travelator. |
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Tim,
Never really understood what im looking for in a star test. I get very good planetary/faint fluffie views but point sources(stars), im guessing thats cos of the diffraction caused by the spyder. Rob "Tim Auton" tim.auton@uton.[groupSexWithoutTheY] wrote in message ... "Robert Geake" wrote: Having now put my mirror right out and back about a thousand times i think i can say i know how to collimate it. One question i have means explaining my checking proccess: Pick a bright star and put it so far out of focus that i fill almost the whole view. If the spyder is central in the brighter area of the view collimation is correct.... Does anyone think this sounds about right? Sounds about right, but a bit imprecise. I've found slight defocussing at the highest magnification you can (to see the airy disk and rings) is more precise - I think that's what is usually meant when "star testing" is referred to. Tim -- Love is a travelator. |
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"Robert Geake" wrote in
: Tim, Never really understood what im looking for in a star test. I get very good planetary/faint fluffie views but point sources(stars), im guessing thats cos of the diffraction caused by the spyder. Rob Have a look at this, Rob http://perso.club-internet.fr/legault/collim.html I didn't respond to your first post because I've mentioned it before, but WTH, I'll only get shouted at. It showed me I needed to take it in stages, and you can't move on until you've done the previous stage as the gross errors have to be cleared before you can see the subtle ones. It's helped me a lot, specially when I suddenly saw a whole specckled effect of very faint stars that (even thogh I couldn't quite see them) weren't even there before. And now my planetary views are much sharper. There's also physical collimation, which is lining up all the bits BEFORE you try to center the optical axis of the mirror down the centre of the tube. So there's another oreference here http://zebu.uoregon.edu/~mbartels/kolli/kolli.html HTH mike r |
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