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Posts Made By: Paul Kammueller

April 12, 2003 02:32 PM Forum: Telescope Making

3-vane vs 4-vane Spiders in Reflectors?

Posted By Paul Kammueller
3-vane spider (as opposed to 4-vane):

Pro: Just 3 vanes instead of 4 to cause 25% less vane diffraction.

Con: Six diffraction "spikes" visible on bright objects instead of four.

The upshot: Less prominent spikes but more of them.

April 16, 2003 03:00 AM Forum: Equipment Talk

Help! I think I royally screwed up my mirror

Posted By Paul Kammueller
?? It's hard to imagine distilled water causing anything so sudden. You sure the dog didn't take a leak on it or something? Did you try to dry it or wipe it with something, something that might have had chemicals in it (you know, like Kleenex with that lotion goo in it or something like that) -- and where did you let it dry -- could there have been something in the air? Pollen, dust, mold, etc?

April 16, 2003 03:32 PM Forum: Religion

My sister died today

Posted By Paul Kammueller
Brian -- my condolences too also. Losing a family member can never be easy, even less so when it is a sibling and so young. While my faith continues to be somewhat nebulous on these matters I hope you take comfort in yours.

April 21, 2003 03:43 AM Forum: Religion

Age and gender

Posted By Paul Kammueller
I've found it interesting just how much more polite and respectful the overall tone and 'feel' of this group has gotten in the days since a lady entered the room. Maybe it's a coincidence.

Reminds me of college days. Guys sit around punching each other, laughing and snorting beer out through their nose and seeing who can fart the loudest. A lady walks in and everybody's having an enlighted discussion about world politics.

April 23, 2003 03:26 PM Forum: Reflectors

Centurian 18/Parks Observatory f3.5 16" Newt

Posted By Paul Kammueller
I'd be very curious to hear about any of the Parks reflectors. These seem to get very good reviews on Excelsis. But they seem conspicuously absent from the used-telescope market. Is it because few have them to start with, or because once purchased, no one ever sells one?

April 25, 2003 05:49 PM Forum: Equipment Talk

Barlow effect on focus

Posted By Paul Kammueller
You almost have to find out by trial and error. Whether it requires more in or out or how much will depend on the amplification factor of the barlow, the length of the barrel its mounted in, the focal ratio of your telescope, and where in the light path you mount it (say before or after the diagonal in a refractor).

April 28, 2003 05:41 PM Forum: Equipment Talk

Casse-fractor telescope design

Posted By Paul Kammueller
Heh heh. Nice! But there are some flaws in the design.

The secondary obstruction is much larger in this case than simply the secondary compared to the objective -- the true secondary obstruction is in effect the size of the hole in the primary mirror relative to the size of that primary which will be disproportionately large for this sort of arrangment, IMHO.

You also have an interesting curve to generate for that primary and secondary since it has to bring to a point focus not parallel incoming rays of light, but already-converging rays, which changes things. You'd need to grind some wacky parabolic elliptical hyperboloidal torus or with a Mobius strip for a secondary. It would be laborious, complicated, EXPENSIVE (!)


April 29, 2003 02:17 PM Forum: Telescope Making

Mars scope

Posted By Paul Kammueller
Nice job, charles! I'm sure that'll be a great Mars scope. I myself built a 10" f/8 (solid tube) and love it. When you take a picture of it, it can be useful to put something in the scene (like a lawn chair or something) to show scale. Pictures tend to make things look smaller than they are.

May 1, 2003 03:47 PM Forum: Equipment Talk

what does triplet mean?

Posted By Paul Kammueller
There is a third lens element (as opposed to the two in a doublet lens) to further correct for chromatic and spherical aberrations which could otherwise be fairly severe in an f/6 refractor such as the scope just discussed.

May 1, 2003 09:12 PM Forum: Religion

Serial polygamy/polyandry

Posted By Paul Kammueller
In the context I've seen it applied, it's been used to describe a case of one man (usually a celebrity or wealthy male) remarrying repeatedly as he ages, but to consistently young women, increasingly younger than himself.

While he never has more than one wife at a time, he effectively monopolizes or "uses up" the child-bearing years of many women (whether or not he actually has children with them), making them unavailable for other men to have for reproductive partners. In this sense it has the same societal, or genetic, effect as concurrent polygamy.

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