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Terry Wood

Jupiter (clearer) Nov 5th 2023 w/Mewlon 180c

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Posts Made By: John Holt

September 6, 2009 01:22 AM Forum: DVDs and Music and Books That You Recommend

Space is Deep

Posted By John Holt

Still very much enjoy these guys. And some of the present day contributions of video artist's.
http://www.youtube.com/watch?v=cULwlnEok1c&NR=1

January 8, 2010 06:51 PM Forum: Equipment Talk

Re: AP 130 on a Teegul Mount?

Posted By John Holt

Barry,
Have you asked the folk's at Astro Physics?
I'd bet they will know what will work from among all possible options.

January 13, 2010 07:17 PM Forum: Telescope Making

Re: virgin teflon source

Posted By John Holt

Steven Sterner said:

Hi , I'm looking for a source for teflon . I'm rebuilding a 13.1" Coulter . Anyone hear of records for ground board bearings ?

Thanks ,
Steve S


Records have been used in years past. But the texture will likely not be a good match with teflon and this heavy of a scope.
Furniture Glides and pebble texture counter top material (like Ebony Star is) works though.

January 24, 2010 06:23 AM Forum: Telescope Making

Re: old Coulter box-n-tube dob

Posted By John Holt

Possibly this. But you might have to call these folks and ask first, to double check thickness compatibility.

http://www.meridiantelescopes.com/edgeguard.htm

May 22, 2003 07:15 PM Forum: Deep Sky Observing

Star Chart

Posted By John Holt

--If you've got a large scope, the Sky Atlas might not go deep enough for you.--

Good point!
I opted for the MSA a few years back, for this very reason. I have never regretted it. My SA2000 is now in limbo.

Check the classifieds here. Deeper field atlases are frequenty available. They are all pretty cool!

john

May 24, 2003 02:54 PM Forum: Pictures of Me and My Telescope and........

Salad Bowl Ball Telescope

Posted By John Holt

Looks neat! The picnic table thing just doesn't cut it for me either. I made a three legged platform for my Astroscan too.

Looking at your mount, I wonder how teflon pads would work? Hmmm....perhaps a trip to K-mart today.

john


May 26, 2003 11:00 PM Forum: Equipment Talk

planetary viewing scopes

Posted By John Holt

If you are considering the Obsession 15 for the circumstances you cite, then go for it.

As has been said, if the atmosphere will not do sub arc second seeing, then you can mask it down (both off and on axis). This is not a project scope. You won't have to upgrade parts. It is high performance, with superior optics and movement. Hand traking at high power is not an issue, if your scope is made for hand tracking at high power. These are. They are also one person scopes: compact and portable.

I had a budget dob. I still have it, but there is very little left of it's original hardware. It still needs more upgrades. Lower power sweeps were wonderful. High power deep sky and planets were not. Until after upgrades. Like those that Obsession (and other premium dobs) have as standard issue. My 3 cents.

john

May 30, 2003 12:47 AM Forum: Equipment Talk

Fine Tuning My Eyepiece Linup

Posted By John Holt

-- Anyway, what else could I add to this (or subtract) to fine tune it? --

You need to add a 28mm, 21.5mm, 15mm, 12mm, 8mm to fill in the gaps. You have no RKE's. How can you observe without no RKE's?

john




July 21, 2003 03:45 PM Forum: Equipment Talk

Baffling isn't it?

Posted By John Holt

It is my understanding that baffling a newt tube may push tube currents (that sneak along the wall of the tube) into the optical path. This does make some sense. Solid tube newts have more issues with tube currents then open tubes do.

The best newt baffling recommendations I have read of involve baffling the bottom of the mirror cell, to shut out intrusive light (but not airflow). Particularly for urban or suburban observing.

john

July 27, 2003 10:13 AM Forum: Equipment Talk

How I avoided aperature fever

Posted By John Holt

I agree with you! There is now way under heaven, or on earth, that I would haul a 13" sonotube out of the basement to observe with it.

A few points here.

Unless your local temps are virtually the same, day and night, this sized scope will not be a "quick-look" scope anyway. Therefore, if the basement is the _only_ place you could store such a scope, then a truss type is the way to go. The optics can be cooling as you set up.

There is a significant differance between an 8" and a 13"(+/-) scope. Optically there is really no contest.

For a solid tube scope this big physically, it is necessary to take realistic countermeasures. Store the scope somewhere else. Make it egonomically useable. Or, as you have correctly deduced, it won't get used.

If you want one (and you would love it!), then reprioritize your floor space options. Store the scope within one doorway of the outdoors. Be it in a breezeway, porch, garage, den, livingroom or whatever. Pick the biggest, accessible doorway you can, and make a minor adjustment in floor plan, that will yield a major adjustment in your night sky viewing. The folks tooling around the sky with the big SCT's do this same thing.

john