Jim Curry
Pooh-Bah
Reged: 10/29/07
Loc: STL
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Re: Post your home made scope
[Re: dave brock]
#5638309 - 01/23/13 06:54 AM Attachment (98 downloads)
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4" f/12 Istar, powder coated, baffled, AP focuser.
Jim
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NHRob
Post Laureate
Reged: 08/27/04
Loc: New Hampshire
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Re: Post your home made scope
[Re: Jim Curry]
#5638320 - 01/23/13 07:18 AM
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Nice. How are the optics on that 4" Istar?
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John Jarosz
Astro Gearhead
Reged: 04/25/04
Loc: Chicago area, IL
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Re: Post your home made scope
[Re: NHRob]
#5638401 - 01/23/13 08:31 AM Attachment (93 downloads)
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Here are the 3 scopes in my sig line
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tim53
Postmaster
Reged: 12/17/04
Loc: Highland Park, CA
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Re: Post your home made scope
[Re: John Jarosz]
#5638682 - 01/23/13 11:05 AM
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This was my first home-made scope. No jive!
8" f/6 Springfield Newtonian, 1981 RTMC Merit award winner.
-Tim
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droid
rocketman
Reged: 08/29/04
Loc: Conneaut, Ohio
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Re: Post your home made scope
[Re: tim53]
#5638712 - 01/23/13 11:20 AM
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Some beautiful scopes so far.  to all
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Víctor Martínez
sage
Reged: 02/05/07
Loc: Cádiz - Spain
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Re: Post your home made scope
[Re: droid]
#5638733 - 01/23/13 11:31 AM
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Here the mine, 16" f5
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idp
sage
Reged: 08/21/09
Loc: New Haven, CT
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Re: Post your home made scope
[Re: droid]
#5638735 - 01/23/13 11:33 AM
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Awesome thread, I learned a lot just by scrolling down.
Mike, I fell in love with your ball mount but frankly, how hard is it to collimate with the trusses instead of the primary mirror?
Ivano
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droid
rocketman
Reged: 08/29/04
Loc: Conneaut, Ohio
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Re: Post your home made scope
[Re: Víctor Martínez]
#5638831 - 01/23/13 12:28 PM
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Victor , like the 16" f/5 on the focuser board, burned in???
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Víctor Martínez
sage
Reged: 02/05/07
Loc: Cádiz - Spain
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Re: Post your home made scope
[Re: droid]
#5638910 - 01/23/13 01:09 PM
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Andy, is a black vinyl adhesive
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StarWrangler
scholastic sledgehammer
Reged: 09/03/04
Loc: Three Rivers, MI U.S.A>
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Re: Post your home made scope
[Re: John Jarosz]
#5638938 - 01/23/13 01:25 PM
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Cool,
The one open Scope reminds me of D. Dillworths Dall Kirkham Folding scope that was in Sky & Telescope some years ago.
Alan O.
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mconnelley
sage
Reged: 03/14/06
Loc: Hilo, HI
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Collimating using the truss
[Re: idp]
#5639021 - 01/23/13 02:36 PM
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Hello:
Collimating the ballscope using the trusses is fairly easy, but a little different than a 'regular' Newtonian. On the plus side, there is no running back and forth since everything is done at the top end. If I get set up before dark, I use a regular Cheshire collimating tool to collimate the secondary and then the primary in the usual way, and that gets me pretty close. Then I look at a star to zero out the coma by adjusting the truss. I look at the star out of focus, and stick my hand into the beam and move it around until the shadow of my hand is on the 'thin' side of the donut (out of focus image of the star). I then know which way I need to move the truss. After a few iterations, the coma has been taken care of. Overall, I'd say that it's no harder than collimating a 'regular' f/4 Newtonian. The collimation seems to hold well throughout a night.
The reason I put the collimation at the top was to allow me to put the mirror farther back into the ball, thus helping balance. The hardware, plus room to allow for the adjustment, would have taken up about 1" of space back there. Also, since the mirror doesn't move relative to the ball, the mirror edge supports are glued to the inside of the ball, and aren't attached to the part of the mirror cell with the triangles and bars. So, from a certain point of view, the ball is also the frame for the mirror cell.
Cheers
Mike
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philipdo
sage
Reged: 12/06/06
Loc: Flanders, Belgium, Europe
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Re: Post your home made scope
[Re: StarWrangler]
#5639066 - 01/23/13 03:10 PM Attachment (97 downloads)
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My trusted 200 mm F/D 20 Kutter Catadioptric Schiefspiegler. Wood & aluminum construction.
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idp
sage
Reged: 08/21/09
Loc: New Haven, CT
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Re: Collimating using the truss
[Re: mconnelley]
#5639071 - 01/23/13 03:11 PM
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Very interesting, thank you. You says that the collimation holds through the night, does it mean that you'll have to repeat it on the following observing night? Even if you do not disassemble the the telescope?
Ivano
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roscoe
curmudgeon
Reged: 02/04/09
Loc: NW Mass, inches from VT
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Re: Post your home made scope
[Re: philipdo]
#5639780 - 01/23/13 11:35 PM Attachment (82 downloads)
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Here's my 60mm f/16.... a Carton objective, long tube made by splicing together two tubes, vintage .965 focuser, dew shield made from a fire extinguisher, Meade alt-az mount found in a customer's basement, used aluminum tripod, now replaced with a home-made cherry wood model.
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kfiscus
professor emeritus
Reged: 07/09/12
Loc: Albert Lea, MN, USA
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Re: Post your home made scope
[Re: roscoe]
#5639806 - 01/23/13 11:55 PM Attachment (67 downloads)
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My redone rockerboard for my Z12. Shortened, lightened, prettified.
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kfiscus
professor emeritus
Reged: 07/09/12
Loc: Albert Lea, MN, USA
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Re: Post your home made scope
[Re: kfiscus]
#5639811 - 01/23/13 11:59 PM Attachment (77 downloads)
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Side view of same. M31 and friends? Top hole (M32) is functional for C5 solar viewing scope, bottom hole (M110) is handle. Rides on dedicated Atomic EQ platform.
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Jim Curry
Pooh-Bah
Reged: 10/29/07
Loc: STL
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Re: Post your home made scope
[Re: NHRob]
#5639823 - 01/24/13 12:07 AM
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Rob:
As one critical observer noted "that the CA for an 4" f/12 was about as good as it gets. The rings were concentric and perfectly shaped" and " this looks lens like it was turned on a lathe, perfect star test images and as good as a 4" achromat can be. He was even speculating that maybe the glass was special and that this wasn't a Fraunhofer design to get such good correction."
It doesn't get better in a 4" than what this scope puts up. I built up a 6" f/12 Istar and I say the same thing.
Jim
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Crayfordjon
Vendor - Zerochromat
Reged: 06/17/09
Loc: UK
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Re: Post your home made scope
[Re: Jim Curry]
#5639991 - 01/24/13 03:36 AM Attachment (102 downloads)
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Six inch refractor made from cat food tins and plastic drain pipes, used for solar imaging.
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Bob Myler
scholastic sledgehammer
Reged: 05/18/06
Loc: St Louis, MO
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Re: Post your home made scope
[Re: Crayfordjon]
#5640971 - 01/24/13 04:03 PM
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Quote:
Six inch refractor made from cat food tins and plastic drain pipes, used for solar imaging.
Friskies, Fancy Feast - or Tender Vittles? 
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titanio
sage
Reged: 02/15/09
Loc: Alicante, Spain
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Re: Post your home made scope
[Re: Bob Myler]
#5641124 - 01/24/13 05:37 PM
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here is mine I will finish it soon
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