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wfj
sage
Reged: 01/10/08
Posts: 260
Loc: California, Santa Cruz County
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To use a smaller diagonal (less obstruction, less intensity in first diffraction ring), replaced "flat-iron" spider with bicycle spoke spider.
Went to a bike store, had them cut spokes with a spoke cutter and thread them with a tool. They
were anodized black, got associated nuts.
Drilled a large fender washer and tube. Patched and painted old spider
holes.
Made two mistakes - mislocated and needed to redrill twice as you can see. Used too long screws - best if the screws are very short.
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wfj
sage
Reged: 01/10/08
Posts: 260
Loc: California, Santa Cruz County
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Close up
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mattyfatz
Pooh-Bah
Reged: 12/27/06
Posts: 1297
Loc: Boise Idaho
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What type of secondary is that? Did it come with the Cell, or is that part of the bicycle?
Have you tested it out yet? are the views noticeably better
--------------------
**Matty**
Stimulating the economy, one piece of equipment at a time.   
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wfj
sage
Reged: 01/10/08
Posts: 260
Loc: California, Santa Cruz County
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It is a Chinese diagonal in a machined metal holder I got off ebay as mfr overage. Went from over 26% CO to less than 18% by diameter!
I've been using it for about a 18 months now. Required a lower profile focuser and moving the mirror down the tube 1.5". On star test, the diffraction pattern shows a brighter center spot, and the first, second, and third diffraction rings are much less pronounced, so can see doubles within the rings a lot better.
On a lark, I've been seeing how far I can push the Coulter mirror. I'm up to 475x on Jupiter/Saturn when it softens, but I'm not done yet. I've identified an issue with the original Coulter cell that's causing a bit of astigmatism in the pattern, which changes when you fiddle with the scope - perhaps the "hose clamp" on the mirror is too tight?
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deSitter
Carpal Tunnel
Reged: 12/09/04
Posts: 2928
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Nice!
-drl
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wfj
sage
Reged: 01/10/08
Posts: 260
Loc: California, Santa Cruz County
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FWIW, I did find the astigmatism from the cell - turns out that the Odyssey wooden cell must be carefully assembled to avoid imparting astigmatism on the mirror.
You must presume that any binding of any clamp, screw, or uneven pressure on a bearing surface (including pads) might slightly twist the mirror. So even a wooden, "low tech" mirror cell has to be treated with due care.
So I'm up to 692x during the brief times seeing allows this. Current limit is a slight TDE (will try a cardboard mask), a very small amount of SA, and a slightly rough surface consistent with a rushed job.
Does seem above what I had expected to find / top out at.
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