cvedeler
Carpal Tunnel
Reged: 12/20/05
Posts: 2124
Loc: Scottsdale, AZ
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Here is the front.
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Chris Vedeler
Astro-Physics 160EDF
Astro-Physics 900GTO
Q453HR / QHY8 CCD camera
Canon 450XSi
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www.aznightsky.com
Scottsdale, AZ
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John Wunderlin
Vendor - Spike-a Focusing Mask
Reged: 10/01/04
Posts: 658
Loc: Mineral Point, Wi
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Who says that's not pretty!?!? It's tricked out! Love it.
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John Wunderlin
Vendor - Spike-a Bahtinov Focusing Mask
Empire Ranch Observatory
Iowa County Astronomers
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Nocturnal
Pooh-Bah
Reged: 09/14/05
Posts: 1004
Loc: CT, USA
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Quote:
Here is the front.
Excellent!
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Best,
Sander
C11-HyperStar on Atlas EQ-Q driven by EQMOD
William Optics M110 With FR-III/TRF-2008
DS2090 guide scope
QHY-8, DSI-Pro and DSI cameras
watec 802h video camera with KIWI OSD
Astro stuff: http://www.tungstentech.com
My Astro Photos
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Tomal
member
Reged: 03/24/08
Posts: 95
Loc: Norway
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Here is my Bahtinov mask, it ain't pretty, but it works. I cut it out from some cardboard and made a holder from some "dew cap material". It goes on like a dew cap and works great!
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Celestron C8 203mm f/10
Meade 5000 series APO 80mm f/6
Sky-Watcher Newtonian 203mm f/5.9
Sky-Watcher Maksutov-Cassegrain 80mm f/12,5
Sky-Watcher Finder/Guide scope 50mm f/4
CG-5 GT
Canon 40D (Unmod)
SSAG
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snowdragonusa
Pooh-Bah
Reged: 09/04/07
Posts: 1125
Loc: Denver, CO
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Nice work folks! Looking good!
Chris - Have you tried removing the Popsicle stick that is blocking the middle slit to see if there is a difference in the clarity of the center diffraction spike? I am curious if there will be a difference.
Cheers!
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Adam
12" LX200R, AT80LE
Lunt 60mm Ha & CaK solar scopes
DMK41.AS, DSI Pro, DSI-C, LPI
Denver Astronomical Society
Brighton Astronomical Group
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jgw12936
professor emeritus
Reged: 03/28/07
Posts: 557
Loc: The Woodlands, TX
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I tried one too, will give it a test run tonight. Scaled the drawing (Thanks Snowdragon!), printed, glued it to a piece of cardboard from the back of a pad of notebook paper, cut a plastic container lid that is a close fit, done. Cost $0. If I like it, I plan to buy John's...
Jim
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Jim
APM/TMB 80/480
Takahashi FSQ ED 106
AP 155 EDFS
Mach1GTO
FLI Proline 11002M
Starlight Xpress SXV-H9/H9C
http://jimwood.smugmug.com/
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cvedeler
Carpal Tunnel
Reged: 12/20/05
Posts: 2124
Loc: Scottsdale, AZ
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Quote:
Nice work folks! Looking good!
Chris - Have you tried removing the Popsicle stick that is blocking the middle slit to see if there is a difference in the clarity of the center diffraction spike? I am curious if there will be a difference.
Cheers!
Well, do to my super high tech design  , the Popsicle stick is integral to the integrity of the unit. Removing it would weaken the structure such that it will not hold a uniform flat shape, essentially bowing like a Pringle potato chip upon installation. You see, my design team (my 2 year old and 6 year old daughters), after minutes of R&D came up with a design that holds on to the dew cap via tension gripage. This was a compensation to slightly poor placement of the plastic angle bits. In the field it turned out to be a feature which renders a nice grip unlikely to fly off in the wind. But as a result places undue tension through the center of the unit requiring the 4 spoke pattern of Popsicle sticks to hold it flat and provide ample gripage. I suspect the curved slats of a Pringle potato chip would render a very interesting defraction pattern. 
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Chris Vedeler
Astro-Physics 160EDF
Astro-Physics 900GTO
Q453HR / QHY8 CCD camera
Canon 450XSi
----------------------------
www.aznightsky.com
Scottsdale, AZ
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cvedeler
Carpal Tunnel
Reged: 12/20/05
Posts: 2124
Loc: Scottsdale, AZ
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I just got a quote back from a local sign company that can cut via a water jet for my design. They want $93! I may be getting one of yours John depending on how well my high tech one holds up.
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Chris Vedeler
Astro-Physics 160EDF
Astro-Physics 900GTO
Q453HR / QHY8 CCD camera
Canon 450XSi
----------------------------
www.aznightsky.com
Scottsdale, AZ
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snowdragonusa
Pooh-Bah
Reged: 09/04/07
Posts: 1125
Loc: Denver, CO
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Adam
12" LX200R, AT80LE
Lunt 60mm Ha & CaK solar scopes
DMK41.AS, DSI Pro, DSI-C, LPI
Denver Astronomical Society
Brighton Astronomical Group
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snowdragonusa
Pooh-Bah
Reged: 09/04/07
Posts: 1125
Loc: Denver, CO
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Quote:
I tried one too, will give it a test run tonight. Scaled the drawing (Thanks Snowdragon!), printed, glued it to a piece of cardboard from the back of a pad of notebook paper, cut a plastic container lid that is a close fit, done. Cost $0. If I like it, I plan to buy John's...
Jim
Hey Jim, let me know how that refractor style mask works out! I am really excited to see if it works better for a refractor than the SCT design.
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Adam
12" LX200R, AT80LE
Lunt 60mm Ha & CaK solar scopes
DMK41.AS, DSI Pro, DSI-C, LPI
Denver Astronomical Society
Brighton Astronomical Group
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Gus_Smedstad
Pooh-Bah
Reged: 07/02/06
Posts: 1108
Loc: Boston 42° 16' N 71° 08' W
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I like the plastic lid idea, though I doubt I'm going to find a 9.25" diameter lid (outside diameter of my 8" OTA).
I did discover that while a Dremmel will cut through foam board very easily, it's also almost impossible to control.
- Gus
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Gus Smedstad image gallery
Orion Atlas 8 EQ-G
Celestron Onyx 80EDF (guiding / widefields).
Orion Starshoot Autoguider
QHY8
Philips SPC900NC
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Nocturnal
Pooh-Bah
Reged: 09/14/05
Posts: 1004
Loc: CT, USA
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I think that constructing a mask like this using strips of opaque material like wood or plastic is a realistic option. Hobby stores probably have thin wooden strips for model building in all kinds of widths. Use a stapler to instantly connect the strips to a central support. Glue works too of course but that takes time to dry. With staples you can space the strips with a spare piece. If you absolutely gotta have aluminum you can get strips of aluminum of various widths at hardware stores. Stapling in out and I think drilling and riveting might not be accurate enough unless you're skilled. Self drilling screws are an option too but the strips need to be clamped firmly.
Options options. Mostly because it seems the gap size really isn't that important.
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Best,
Sander
C11-HyperStar on Atlas EQ-Q driven by EQMOD
William Optics M110 With FR-III/TRF-2008
DS2090 guide scope
QHY-8, DSI-Pro and DSI cameras
watec 802h video camera with KIWI OSD
Astro stuff: http://www.tungstentech.com
My Astro Photos
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cvedeler
Carpal Tunnel
Reged: 12/20/05
Posts: 2124
Loc: Scottsdale, AZ
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Quote:
I did discover that while a Dremmel will cut through foam board very easily, it's also almost impossible to control.
- Gus
A Dremmel is WAY overkill for foam board. I can just picture the foam flying everywhere! The easiest way to cut foam board is with a razor blade. My ex-wife does quilting and for fabric they have a rotary cutter. Basically a circular razor blade you can run along a straight edge. Makes perfectly straight cuts on fabric and foam board. I used hers to make my light box out of foam board. The only tricky part would be the ends of the cuts. Perhaps you could cut it to within an 1/8th of an inch and finish the cut with a utility razor blade.
Lots of great ideas! I may be looking for my next generation using foam board. Hmmmm.
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Chris Vedeler
Astro-Physics 160EDF
Astro-Physics 900GTO
Q453HR / QHY8 CCD camera
Canon 450XSi
----------------------------
www.aznightsky.com
Scottsdale, AZ
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jgw12936
professor emeritus
Reged: 03/28/07
Posts: 557
Loc: The Woodlands, TX
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Adam,
I'll let you know how it goes, I have everything set up and ready to go, and my clear sky clock looks perfect!
Jim
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Jim
APM/TMB 80/480
Takahashi FSQ ED 106
AP 155 EDFS
Mach1GTO
FLI Proline 11002M
Starlight Xpress SXV-H9/H9C
http://jimwood.smugmug.com/
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Joe G
scholastic sledgehammer
Reged: 01/10/07
Posts: 757
Loc: Southern California
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Does anyone think that you can print this out on that clear transparency paper (plastic) that teachers use for overhead projectors?
That way you wouldn't need to make any cuts. Just print it out and tape it to the end of the scope. Would the clear plastic cause any problems?
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Tak FSQ 106N, 8" F4 GSO, 10" F4.7 Orion
CCD Labs Q453 (Q8)
TSS Modded Atlas
My Flickr Astrophotos:
http://www.flickr.com/photos/10168933@N08/
Click on the image->All sizes for larger images
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John Wunderlin
Vendor - Spike-a Focusing Mask
Reged: 10/01/04
Posts: 658
Loc: Mineral Point, Wi
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Quote:
Does anyone think that you can print this out on that clear transparency paper
Back a few pages, I posted that I tried this approach. You can see the spike pattern, but it's distorted a bit. When I added the CCD imager to it, it was unusable. However, I was just hand-holding it. If it's mounted in a rigid frame it may work better. Unless the optical quality of the material is better than what I used, you really need to cut out the clear parts.
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John Wunderlin
Vendor - Spike-a Bahtinov Focusing Mask
Empire Ranch Observatory
Iowa County Astronomers
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Joe G
scholastic sledgehammer
Reged: 01/10/07
Posts: 757
Loc: Southern California
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Thanks. It's a long thread making it tempting to skim through much.
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Tak FSQ 106N, 8" F4 GSO, 10" F4.7 Orion
CCD Labs Q453 (Q8)
TSS Modded Atlas
My Flickr Astrophotos:
http://www.flickr.com/photos/10168933@N08/
Click on the image->All sizes for larger images
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Old Dinosaur
Pooh-Bah
Reged: 05/08/07
Posts: 1223
Loc: Out in the sagebrush
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I'd think it would work best if whatever the material, it was finished in flat black. And if, at least the sides, of all the slots were as smooth and straight as possible for the sharpest diffraction pattern.
I know all the masks I've made over the years worked best with smooth sharp edges for any of the hole patterns I've tried.
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WRS Observatory
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raf1
super member
Reged: 11/18/05
Posts: 142
Loc: Texas
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Hey Jim - very nice design and I noticed that you're also from the Lone Star state. What is it that gives us Texas boys that flair for elegant design and cutting edge vision for manufacturing? I dunno - just blessed I guess. As you can see, I've raised the construction bar a bit so don't take offense at this new entry in the Bahtinov mask design contest. Introducing the “South Texas Chinet Focus Mask”. That's right folks, that cellulose fixture at all Fourth of July horse shoe throwin', washer pitchin', dominoe shufflin', barbeque eatin', Shiner Bock drinkin' family tradition get-togethers! The Chinet paper (actually cardboard 'cause nothin’s too good for the family) picnic plate. Ok, I know you're dyin' for the details so here we go. Downloaded Inkscape and used Adam's mask file (thanks Adam!). Printed it out and Scotch taped it to the aforementioned construction material. I then used the sharpest skinnin' knife I had and cut out (actually chopped out) the mask using Adam's template.
As you can see it is a quick and dirty prototype so I’m really pushing the limit on tolerances required to achieve successful focus. I’ll be reporting back on my "first light" results as we are expecting some pretty good local weather this weekend. Seriously though, many thanks to Pavel for the idea, Dennis for the news and Adam for the scalable vector drawing. This has really been a thoughtful thread and I’ve learned a lot from you guys so “thanks” to you as well.
Ron
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-Ron
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Too much "stuff" and too little time to use it .....
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Nocturnal
Pooh-Bah
Reged: 09/14/05
Posts: 1004
Loc: CT, USA
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I'm curious if instead of slats you could use wire spaced at the appropriate interval. I've always been amazed at the diffraction pattern you get from fishing line in a cross. There's going to be some weather the next few days so I won't be able to try this out. If someone else does, let us know how it goes 
I imagine a frame from foam board would be rigid enough to allow enough tension on the wires to keep them straight.
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Best,
Sander
C11-HyperStar on Atlas EQ-Q driven by EQMOD
William Optics M110 With FR-III/TRF-2008
DS2090 guide scope
QHY-8, DSI-Pro and DSI cameras
watec 802h video camera with KIWI OSD
Astro stuff: http://www.tungstentech.com
My Astro Photos
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