orion63
super member
Reged: 12/10/07
Posts: 140
Loc: Lima, Peru
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Here is my first shot at a Z folded refractor. It is meant to serve just as a proof of concept. It uses my 70mm f12 and a couple of really cheap second surface mirrors (I know, I know, but I only wanted to make sure the design was ok). It took me far more time to design it than to build it, and the results are very encouraging. The main goal was an as-compact-as-possible spotting scope using this objective.
I was amazed to be able to see an image the first time I put an eyepiece to it. Collimation was not an issue. Shadow images due to the second surface mirrors are perceptible, but not as annoying as I thought, especially in daylight use. These cheap mirrors loose too much light to be comfortable in the night.
I am really intrigued by this concept, the result is really portable and I am sure that with proper mirrors and objective this can make for a very good travelscope.
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orion63
super member
Reged: 12/10/07
Posts: 140
Loc: Lima, Peru
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Without the diagonal and eyepiece, at 29x20x10 cms, it is smaller than the proverbial shoebox.
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orion63
super member
Reged: 12/10/07
Posts: 140
Loc: Lima, Peru
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Here is the first mirror cell. I masked the squared mirror with sand paper painted flat black. Using my 32mm Plossl, this scope gives very reasonable images. Changing to higher power eyepieces reveals the deficiencies of the cheap mirrors, which was expected.
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orion63
super member
Reged: 12/10/07
Posts: 140
Loc: Lima, Peru
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The interior, showing the second mirror and part of the objective. This scope lacks buffles, and it shows, specially when the sun is at the side of the view. I have an idea of how to buffle this, but been just a proof of concept, I thought it wasn’t worth the work.
I believe that sometime I will build a “real” travelscope using this concept, but I am not sure when.
Gonzalo
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ssatko
scholastic sledgehammer
Reged: 03/05/05
Posts: 905
Loc: NC
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Neat concept--thanks for sharing, Gonzalo!
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Scott
SV80/9D
SV102ABV
Orion 4.5" Starblast
Meade LX90 8" UHTC
Orion XT12i
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Sky Captain
Metal Whisperer
Reged: 11/07/04
Posts: 7195
Loc: Issaquah, WA.
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Great project and design Gonzalo. 
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Equipment Overload!
Kerry
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strix
sage
Reged: 07/21/05
Posts: 288
Loc: southern Chile
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Brilliant 
Just buy some first surface mirrors at Surplus Shed and you're done or, if you want going really cheap, follow my recipe "pour some paint remover on the painted back surface of the mirror and left it alone all night long inside a plastic bag (fumes are toxic and flammable). Next day, carefully remove the jelly-like substance with some cotton swabs drenched on WD-40, trying not to scratch the surface (use cotton swabs liberally). Wash your mirror with warm water and some dish soap with the aid of pure cotton swabs, rinse with tap water and then with distilled water, let it dries and it's done". Think about a dewshield just to avoid lateral glare.
Best regards
David
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Homemade 80 mm f/5 refractor (Starcat)
Homemade 80 mm f/11.3 refractor (Astrix)
Homemade 83 mm f/12 refractor (Astrix-Jaegers)
Homemade 114 mm f/8 newtonian (Silverghost)
UNITRON 105 mm f/15 refractor (older than me...)
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Vincent Becker
super member
Reged: 09/16/08
Posts: 198
Loc: France
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Really nice project. It looks really good for just a "proof of concept".
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Vincent Becker
10" dobsonian on EQ platform (home-made by my father)
8" string newtonian as travelscope (home-made by myself )
Orion 80ED and GSO 200/1000 on Atlas EQ-G for astro-imaging
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rustynailz911
professor emeritus
Reged: 01/30/08
Posts: 545
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More proof that some of the most incrediable telescope builders in the world are right here on cloudy nights.Hats off to you sir that is a verry cool inventive project.
Russ
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4.5"F8 Newt
9.7mm Meade 4000 Plossl 52 Deg FOV
15mm Meade 4000 Plossl 52 Deg FOV
26mm Meade 4000 Plossl 52 Deg FOV
2x Shorty Acromatic Barlow
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Gary Fuchs
scholastic sledgehammer
Reged: 05/22/06
Posts: 867
Loc: Easton, PA, USA
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Nice!
Gary
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Luigi
Post Laureate
Reged: 07/03/07
Posts: 4941
Loc: MA
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There a few spotting scopes built in this format. The Leupold 60mm Golden Ring is one that comes to mind.
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17.5" f/5 Dob. IM-715 MCT. 120ED. Lunt 60mm Ha.
Zeiss, Leica, Fujinon, Nikon, Pentax, Bushnell bins
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orion63
super member
Reged: 12/10/07
Posts: 140
Loc: Lima, Peru
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Thanks to all. I am really happy with this project that actually started with a post by Randy (randtek).
http://www.cloudynights.com/ubbthreads/showflat.php/Cat/0/Number/2666106/page/0/view/collapsed/sb/5/o/all/fpart/1/vc/1
Yep, I've identified the right mirrors at Surplusshed. I want to polish the idea a little bit and find a more suitable objective. I believe that a 70mm to 80mm will be ok, but I want to find a longer FL, maybe an f15. We'll see.
Yesterday we had a clear night and I took it for a look. The stars were tripled by the mirrors, which is very annoying. But in daylight it is ok. I gave this scope to my daughter as an improvement over the 50x600 I build for her a year ago. She's happy and so am I 
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StarStuff1
scholastic sledgehammer
Reged: 04/01/07
Posts: 979
Loc: South of the Mason-Dixon Line
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Hey Gonzalo, this is the same design I have for a solar projection refractor in a thread I started several days ago. The design does work very good. Congrats on a nice looking project that will only get better as you improve it.
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Tools that make objects very far away appear much closer than they actually are.
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orion63
super member
Reged: 12/10/07
Posts: 140
Loc: Lima, Peru
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Terry, that SS 70/800 achromat you were considering is the same I used in my project. I just remembered it is not really an f12, but an f11.4. It is a fine lens for the price. When I used it for my first DYI refractor, it gave me nice views of Saturn.
Edited by orion63 (03/21/09 03:25 AM)
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StarStuff1
scholastic sledgehammer
Reged: 04/01/07
Posts: 979
Loc: South of the Mason-Dixon Line
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Thanks for the info on the lens, Gonzolo. I also found an 80mm f/10 in a cell for only $5 more so I will probably go for a little more aperture.
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Tools that make objects very far away appear much closer than they actually are.
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RRPG
sage
Reged: 01/26/08
Posts: 362
Loc: 42° 25'50" 123° 19'00"
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looks like one half of a large wood binocular, for some strange reason. Just on a larger scale. Nice proof of concept though. I have a cople of odd scope laying around, could be an intersting project.
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Peter
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8 in HO Truss Dob
8 in. Skywatcher SCT
C102XLT
ETX 90 EC
C80ED
CG5-GT
WIP: 14 inch HO Truss Dob
Canon 450D Xsi
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orion63
super member
Reged: 12/10/07
Posts: 140
Loc: Lima, Peru
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Peter, actually I as considering using this basic design for a binocular using a couple of 60x900 I have. I haven't studied binos, but I believe they have some design complications that I have to resolve. Maybe for another "proof of concept"?
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jeffg
member
Reged: 02/13/07
Posts: 66
Loc: Irvine CA
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Now I know what to make with that same 70mm lens from the Shed
that is sitting on my desk!
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Jeff
14", 10", & 4.25" Dobs
8" Schmidt Newtonian, C-8 SC, 8" LSC
6" Cave Student Model A, 6" Dall-Kirkham, 6" RV-6
5" Refractor & 80 mm Folded Refractor
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