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24% Of Diameter Obstruction By The Secondary?

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Posted by Martin on May 24, 2001 07:40:11 UTC

Thanx for recomending Harry siebert to me! :) I've done some research about him and his eyepieces and I was thoroughly amazed! I allso called him up and he was a real joy to talk to! I haven't decided yet but I'm really thinking in the ways of buying some eypieces from him. If half of what I've heard is true he makes some killer eypieces, and after talking to him yesterday I feel very reassured that everything they say is true :)

On to the secondary. The 2.25" secondary is something I haven't seen yet unfortuenately :( I've only been able to find 2.14" and the next step is all the way up to 2.37" or 2.4". Unfortuenately a 2.4" secondary would mean that I have a 24% blocking of the diameter of my main mirror. I don't know exactly how much this would affect the contrast but somehow it feels like it could actually make quite a big difference? As I said before ( I think :) I plan on using the telescope for deepsky observing and so I would be willing to trade some contrast for a larger 100% ilumination of the eyepiece. But I'm affraid that it will get out of hand and just kill the contrast :( I've been looking a lot on the 2.14" and actually as I wrote this I found one company that supplies 2.17 (not a big difference but still :) that would probably be able to get me into the .4 degre area of 100% if I built the tube a litte narrower. Suggestions?


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