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Anybody ever buy one of these???

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8 replies to this topic

#1 Tom T

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Posted 19 January 2004 - 01:01 PM

Get a load of the 29" sonotube coulter!

http://mysite.verizo...coulter0684.jpg

It makes the 17.5 seem positively tiny. I'd LOVE to see a review of that beast. Thank goodness for the truss design.

Tom T.

#2 Don W

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Posted 19 January 2004 - 01:33 PM

Well my 17.5" Odyssey (nicknamed Oddity) gave a wonderful example of astigmatism. It was ok at low powers. Mechanically, it was a nightmare. It creaked and groaned and the movement was sticky. After about a year I rebuilt it as a truss dob and won an award at Astrofest. It was the big box design that was popular in the mid 80's. The following year, I sold the mirror and replaced it with an 18" Galaxy. Just had to do a little work on the mirror cell and replace the truss tubes. Some dentist from southern Wisconsin came to Astrofest and set up his sleek new dob design next to me. When I saw it, I knew it was back to the drawing board. His name is Dave Kriege and he named his scope Obsession 1. We became good friends. :winky:

I heard that the 29" did very poorly, the mirror 'potato-chipped'. Basically that means that it was so thin that it tried to 'fold over' and it just threw off the figure terribly. They only sold a couple of those monsters, thankfully.

#3 Guest_**DONOTDELETE**_*

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Posted 09 February 2004 - 08:05 PM

Optical quality in Coulter mirrors...well they wer very good.

I had a full thickness 14.25" dia. Newtonian on a Cave Mount and optically it did a very good job even on planets.

I had a friend who bought a Dobsonian 10.1" it too performed well.

It is likely that inadequate mirror support on the thin and larger mirrors caused them to warp and introduce astigmatism.

That is why the larger the thin mirror Dobsonian the point mirror support points they need.

Dan Kahraman

#4 tishovlin

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Posted 10 February 2004 - 06:55 AM

I have a 13.1 Coulter optics dob, and I consider the mirror to be very good, although I am nowhere near an expert. I remember seeing the double-double before I even knew it was the double-double. I had no idea that some people considered it a challenge to split. M13? Wow!!
What could this mirror do if it was mounted in a truss-tube design and allowed to ventilate? I think that is the main drawback of the original tube design, only one opening for air to get in and out. I don't see why potato-chipping should be an issue unless you're looking down near the horizon. I just got a copy of Krieg and Berry's book, and I am going to give the 13.1 a home it deserves, a truss tube 18 point flotation system. Great book, by the way! The coulter optics mirrors are thin, but if they are supported correctly, and well collimated, there is no reason they should not perform as well as a full thickness mirror. As a matter of fact, they should stabilize thermally quicker than a 2 inch thick mirror.

Tim S

#5 desertstars

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Posted 10 February 2004 - 10:52 AM

Last time I saw something like that they were firing a clown out of it and into a net!

#6 matt

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Posted 10 February 2004 - 03:31 PM

That used to be my kind of teenage dreams!

#7 LivingNDixie

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Posted 10 February 2004 - 05:29 PM

.... gave a wonderful example of astigmatism

Don,
Consider that quote saved for posssible further use :bigshock:

#8 Guest_**DONOTDELETE**_*

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Posted 10 February 2004 - 05:54 PM

Last time I saw something like that they were firing a clown out of it and into a net!


LOL :cool:

#9 PMB

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Posted 22 February 2004 - 09:39 AM

WOW! The scope that devouered Cleveland! :p


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