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20 inch f/3.55 Telescope at the September 2011 Oregon Star Party
 
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20 inch f/3.55 Dobsonian
First Light: January 7th, 2011 

This Telescope was designed by (me) Greg Babcock and Nate Currier of Aurora Precision and built by Aurora Precision.  It was built mostly out of Aluminum.  Many components were "off the shelve" products including the Truss Clamps,  The Astro-Systems Spider features a heated Secondary Holder.  The Mirror is 1-5/8 inch thick Pyrex made by Swayze Optical. 
 
The goal with the new scope was to increase ease of use and mobility.  It was patterned after the 12 inch Traveler.  A lot of the anxiety comes from transporting the scope.  The 12s hard Baltic Birch Mirror Box protects the scope during transport.  The 20s aluminum Mirror Box Case does the same.  The 20's heaviest piece is the Mirror Box, 65 pounds, its physically small (22.25 inches square), adding to the ease of handling.

To assemble, the Mirror Box can be lowered between the lock-able Alt-Bearings onto a guide track.  The height of the 20 permits attaching the Cage, and viewing, without a ladder.  And no ladder is required for observing.  The Mirror Box easily goes through a narrow RV door and travels well in the small vehicles.
The Cage design features 2 thin "Alucobond"  rings, with Aluminum spacers.  Tension from the Spider gives the Cage torsion strength.  This strong Cage is attached directly to the Trusses.   A del-ran Bridge between a Truss and Focuser Board, supports and stabilizes the Focuser Board.   It replaces what would have been an additional Cage ring.  A 20.25 inch Light Baffle just in front of the Primary Mirror and Cage rings only 21 inches in diameter, add contrast to the view.   The physical Size of the Scope is closer to that of an 18 inch.  The Telescope weighs 114 pounds. 

The Images don't do this Telescope justice.  The architecture could be described as an industrial look.  The red accent enhances the appearance.  


Top Image note:
 
At September 1st., 2011 Oregon Star Party (OSP).  From Left to Right,  My 20 inch f/3.55,  Howard Banich 28 inch f/4 with black shroud, Mel Bartels 13 inch f/3 on aluminum stand.  Dave Danskey's 16 inch on Equatorial Platform (right).

Above image Is the first "operational" use; August 26th, 2012 in Central Oregon.  First Light January 7th, 2011 5:40pm-Cresent Moon.  


















Televue 76mm
The TeleVue 76mm APO Refractor (aka TV76)

Ordered:  September 2001

The 76mm is the smallest of the 3 Telescopes, but gets the most variety of assignments.  It was fitted with a Coronado H-Alpha Solar Filter.  The 8-24mm Zoom Eyepiece gives 20x-60x for Solar Viewing. 
The APO design makes the 76 excellent for night viewing including Planetary and "Rich Field" viewing.  The 40mm Pentax yields 5.8 degrees at 12x.  I installed a JMI Motor for the Focuser for fine tuning focus for imaging.   The  76mm is the size of the old 70mm Pronto and fits in an airline carry on case.  It went to The Venus Transit in 2004 and the Solar Eclipse in 2009 to image these events.  It also Imaged the 2012 Annular Eclipse and the 2012 Venus Transit.
The Takahashi Teegul Mount
This is the only Tracking Mount that I own. I acquired it in 2003.  It is accurate, compact and an excellent traveler.  Custom made Solid Aluminum "Latitude" 
Wedges" machined to 30 & 45 degrees.  They are interchangeable depending on the Telescopes travel destination.  They can be stacked to give Latitudes from 15 degrees up to 75.  Latitude Fine tuning is achieved by adjusting the Tripod legs.  The "C" Cell Battery pack was replaced by a lighter "AAA" battery pack.  For the 2009 eclipse, the counterweight shaft and Latitude wedges were left off to make the Mount a lighter "Alt-az" since ship board observing did not require an Equatorial Mount.  The Mount is very versatile.
Serial Number on this Telescope is 1031.  It was ordered at the Mt. Bachelor Star Party as soon as I found out it was going into production.







 
Normally, I wouldn't list Binoculars as a Telescope, but this is actually my most used Telescope for its "grab and go" qualities.  No tripod or setup is required to observe.  The image stabilizing features eliminates the jiggling motion and gives a "floating effect."

These Binoculars have been fitted with filter adapters, that allow me to attach a UHC filter for observing objects like the North American Nebula and Veil Nebula.  I only put the filter on one lens and let the high contrast, view balance with the natural view. 
These Binoculars provide a 6.5 degree field of view making objects easier to located.  It has a decent 4.2mm Exit Pupil and its compact size and relatively light weight, makes it easier to hold.  The 15x50 Canon IS were an attractive consideration for their power, but the 10x42s size weight, exit pupil and field of view won out.  

See My e-book:
Stargazing for EVERYONE with Binoculars

Canon 10x42
 Image Stabilizing (IS) Binoculars
Acquired March 2014



 
 
 
  The Traveler 
My Current Telescopes     The Travelers     The Ultra Lights     My Early Newtonians     My Refractors     For Beginners    Telescope Links
12 inch f/4.9 Traveler
  In August of 2006, while sitting in the Atlanta Airport, waiting for the connecting flight to Portland, I began to sketch the new Traveling Telescope design.   We had just completed our Argentina trip.  Lessons learned from traveling with the 10 inch would be used in the new design.  The new 12 inch Telescope had the same origin as the 10 inch. A "Classic style" (full metal tube) 12 inch was purchased and many components were retained.  Improvements over the 10 inch were, the detaching Rolling Cart.  Collapsing trusses for easier stowage.  The lid acts as a ground board in a pinch. 
12 inch Traveler
Side view


  12 inch Traveler
Front view 
The Carry on Box-
Brown 10 inch next to the black 12 inch.
 
Volume is similar between the two.





First Light-March 30th, 2008, 9:00pm - Orion Nebula 

Status: Now Joni's Telescope

         
 

More on Telescopes
 For Beginners 
My Current Telescopes     The Travelers     The Ultra Lights     My Early Newtonians     My Refractors     For Beginners    Telescope Links
For beginners I recommend an 8 inch Dobsonian with 3 to 4 good eyepieces (Plossls or better), including a good low power eyepiece.  What a lot of beginners soon learn is, the low power eyepiece is the most used.  

The Dobsonian is suitable for beginners and experienced observers a like.  My 20 inch is a Dobsonian.  Why Dobsonians and why this one?  It offers great value for the cost.  It assembles in about a minute.  The eyepiece is near the top of the Telescope, making it comfortable to look through.  An 8 inch is a serious aperture with almost twice the light gathering power of a 6 inch without adding a lot of weight.  It travels well in small vehicles. 

I do not recommend "goto" mounts for beginners.  I like the concept, but they are often troublesome to operate.   In reality, we still need to know the sky and what is worth looking at on a given night.  That comes from websites, books, charts and experience. 
  Dobsonians do not track, but you will find them easy to operate.  Equatorial Mounts with their tarcking is nice to have, but can be expensive, and awkawrd to transport and setup.   This is the quickest way for your scope to end up in permanent storage.

 Equatorial Mounts are excellent for imaging, but I have seen the interest in imaging faulter as quickly as it comes.  I recommend giving the casual observing a try first. For observing, you want as large as you can get.  But if you want to Equatorially mount it, you will need a monster mount for a stable image.   I myself use a small dedicated Telescope for imaging and I would recommend that for everyone.  A small scope can be a good imager and you can still use it for observing.   For me, I use the TV76 shown above.
   
 
 

Telescope Links 
My Current Telescopes     The Travelers     The Ultra Lights     My Early Newtonians     My Refractors     For Beginners    Telescope Links
         Sub f/4 Telesscope Links
       
Mel Bartels
fleet of f/3s
  Lockwood
14.25 f/2.6
  Ken Lulay
8 inch f/3.8
  Ward-Pekurar
12 inch f/2.8
  Swayze
10 inch f/3
                 
 
Short f/ratio Telescopes, Seconday Mirrors are large
What is the MINIMUM size that your Secondary Mirror's minimum Axis should be?

Minimum Secondary Size Equals (d) divided by the ( f/Ratio) of your Telescope..
d = the center of the Spider to the Focal Plain when the Telescope is focused at Infinity
. 
My 20 inch Telescope:  d = 13.75 inches.  The f/Ratio = 3.55. 
|Minimum Secondary Size = 3.87 inches

The 20 inches Secondary's actual aperture, al20 inches.
source: Gary Seronik.com
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