| Andy Taylor |
| (twistin' by the pool) |
| 07/01/09 03:21 PM |
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Compact refractor
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Hi all...
I'm considering building a lightweight compact refractor for travelling.
At the moment I'm thinking of using a 100mm F4 objective and then further down near the focuser using a negative achromat to bring it to around F8...basically a full time barlow lens. What is the best placement?
Can anyone point out the pitfalls of doing this...?
| Owen |
| (professor emeritus) |
| 07/02/09 09:25 AM |
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Re: Compact refractor
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Why not just fold an F8..?
Owen
| tim53 |
| (Pooh-Bah) |
| 07/02/09 09:28 AM |
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Re: Compact refractor
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Quote:
Can anyone point out the pitfalls of doing this...?
CA out the wazoo?
-Tim.
| Andy Taylor |
| (twistin' by the pool) |
| 07/02/09 09:47 AM |
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Re: Compact refractor
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Quote:
Why not just fold an F8..?
Owen
Yeah - why not make it...
TELESCOPIC!
DOH...!
| Owen |
| (professor emeritus) |
| 07/02/09 10:01 AM |
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Re: Compact refractor
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Theres no reason why a refractor needs a solid tube - using trusses could bring the poratbility you desire
Owen
| Gordon Rayner |
| (scholastic sledgehammer) |
| 07/03/09 07:55 PM |
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Re: Compact refractor
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Have your seen the folded refractor in AMATEUR TELESCOPE MAKING, edited by Stephen F. Tonkin, from Springer?
I have two 10 5/8 inch airspaced doublets, in cells, f/10, and am considering making such an instrument( and in selling the other lens).
| drexelpbp |
| (sage) |
| 07/05/09 11:12 AM |
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Re: Compact refractor
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Hi Gordon
I have that book and I am also interested in making a similar instrument.
I was looking for other sources of design information on this kind of scope and also sources for objectives(I was thinking 8" f/10).
If you sell your objective how much are you looking for?
Thanks
Gary