FarmerDave
sage
Reged: 09/07/07
Posts: 410
Loc: Northern Virginia
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Quote:
I just noticed a nit- the file name generated is 'bhatinov' but should be 'bahtinov', FYI.
Dang it!  I caught that in 9 places, missed it in the 10th. I'll fix it next time I get a chance. Thanks for pointing that out.
Thanks everyone for the kind words - this was actually kind of fun (and a learning experience) for me to put together.
Just to see what happened, I tried to convert the SVG to DXF using a couple of different programs - it wasn't pretty. In one case, the conversion converted the curves in the wrong direction, and in another, the clipping paths weren't honored, so the DXF ended up with lines all over the place where they didn't belong, so it took a good bit of manual editing to get it right.
I'm off for the weekend, I'll catch up with this thread in a few days - happy masking.
David
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Celestron C6/C9.25/CG-5GT Mount
Orion 80ED/EON 72/Supercharged Atlas EQ-G
Garrett Optical Signature Series 10x50
Canon XTi (soon to be modded)/Canon 40D (unmodded)
Meade DSI/Meade DSI Pro/Philips SPC900N
1944 Ford 2N/1948 Ford 8N
Bahtinov Mask Generator * AstroCataLink * 40DShutterCount
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Elliot
super member
Reged: 09/12/06
Posts: 123
Loc: Medford NJ
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John - When are the masks shipping?
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Celestron CPC 1100
APT Wedge
Celestron ED80 GuideScope
SkyShed
SBIG ST9XE
Celestron Ultima 2000
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raf1
super member
Reged: 11/18/05
Posts: 130
Loc: Texas
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Hi Adam - as you know I had great success using your Inkscape template for my mask. Since David has released his mask generator I decided to create a test mask using that as I still need to create masks for two other refractors. I went ahead and re-created a mask for my TEC160 and noticed that David's generator has less slits than the one Inkscape creates. Question: Any idea what more or less 90 and 20 degree slits does to the diffraction spike pattern? Of course less cutting by hand would be preferable but not at the expense of degrading the focusing spikes!
Thanks,
Ron
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-Ron
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Too much stuff and too little time to use it .....
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snowdragonusa
Pooh-Bah
Reged: 09/04/07
Posts: 1088
Loc: Denver, CO
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Igor - You will most likely need to cut it out. The optical quality of the transpaencies will probably affect the final focus... just like if you were to put a less expensivefilter on your EP, focus, and then remove it.
Ron - He added the ability to dictate how many lines there would be in the mask. All in all this should not effect the diffraction spikes much. This biggest issues fewer cutouts would cause would be to decrease the light and therefor not able to focus on dimmer stars. Personally I like having as much light coming through as possible. Thats one of the big pluses over the traditional Hartmans.
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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John Wunderlin
Vendor - Spike-a Focusing Mask
Reged: 10/01/04
Posts: 501
Loc: Mineral Point, Wi
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Quote:
John - When are the masks shipping?
First batch will be shipping early next week with any luck.
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John Wunderlin
Vendor - Spike-a Bahtinov Focusing Mask
Empire Ranch Observatory
Iowa County Astronomers
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upgrader
member
Reged: 11/09/06
Posts: 12
Loc: Stockport UK
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Here's my effort
Thread on how I made it is here SGL
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SkyWatcher 250PX + ED80 Piggybacked
SkyWatcher EQ6 + EQmod
Modded Canon 350
QHY5 Guider
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raf1
super member
Reged: 11/18/05
Posts: 130
Loc: Texas
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Hey Adam - thanks for your response and I appreciate your comment about decreased light entering the OTA. I compared the masks to one another and considering that the spacing of the cutouts is dictated by the number of the cutouts, doesn't look like I would lose much light at all (especially since I used a 2mag star to focus with your mask). I'll cut out the mask made with the generator and compare focus through both and report back. May be a while though as a little complication named Ike is mucking up our skies.
Cheers,
Ron
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-Ron
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Too much stuff and too little time to use it .....
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smokin oakum
Pooh-Bah
Reged: 09/24/07
Posts: 1497
Loc: Wilmington, NC
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Ok, I've found someone with a plasma cutter that can make one of these. So I have two designs that I'd like your opinion on.
Which one of these would you go with? The left one, or the right?
Neil
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Broadcasting live views of the night sky @
Sparkcast
C11 CGE / Hyperstar
MallinCam Hyper Plus Color
Orion 12" XTi f/4.9
MoonLite Focuser
Round Table Platform
12" Parralax rings
Cape Fear Astronomy Club
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snowdragonusa
Pooh-Bah
Reged: 09/04/07
Posts: 1088
Loc: Denver, CO
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Hmmm, well if cost isn't an issue o with both and see if there is a difference for your scope. I think it would be a great experiment that others here would thank you for carrying out.
Otherwise I think I would go with the more slender slats.
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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raf1
super member
Reged: 11/18/05
Posts: 130
Loc: Texas
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Hey Neil - Adam's right, would appreciate the comparison as that is exactly what I was going to do when the weather clears. Let us know what differences you see.
Thanks.
Ron
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-Ron
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Too much stuff and too little time to use it .....
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hiro
sage
Reged: 07/17/07
Posts: 386
Loc: Tokyo
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Hi all,
I thought that the minimum requirement is precise straight lines to make clear diffraction spikes and that it may be possible easily with fine fishing line.
full size image here:
http://farm4.static.flickr.com/3132/2852140265_0cfd4dd761_o.jpg
You can see two sets of diffraction maker.
The left is for my refractor. This is made of fine fishing line and a round toy badminton racket for kids.
You see a sample here:
http://www.johnlewis.com/230417814/Product.aspx
The right is for camera lenses. This is made of the same fishing line, alpha-cyanoacrylate adhesives, and a cheap round towel ring.
Setting was easy and cheap with Scotch tape.
This is a 100% crop showing the spike with the racket and my refractor at F3.6.
The lines are a little bold. I suspect it due to the fact that the racket is not exactly round.
original full size image here:
http://farm4.static.flickr.com/3123/2852974740_be6c930574_o.jpg
This is a 100% crop showing the spike with the towel ring and camera lens at F2.8.
original full size image here:
http://farm4.static.flickr.com/3238/2852141549_9e03c469ac_o.jpg
Thanks Dennis Sakve,
I could be confident about focussing for the first time.
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hiro
Canon EOS 5D / EOS 5D-AP / EOS 5Dmk2 sp2 by Seo san
Takahashi FSQ-106ED with reducer, extender, and "hiro design" off axis guider
Takahashi EM-200 temma 2 jr
Kenko Skymemo-R
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isramirez
scholastic sledgehammer
Reged: 11/04/05
Posts: 869
Loc: Mexico City
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Quote:
Here's my effort...
Outstanding mask!!!
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Santel MK9 & MK6
IntesMicro 715
Celestron SCT6 & ONIX80 EDF
Meade SN6 & AR6
HiOptic 6in MakCass.Gregory
DBK + DMK + NexImage + LPI
CG-5 & LXD75 Mounts
many EP's, Barlows and Binoviewers
Great astronomic passion 
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groz
scholastic sledgehammer
Reged: 03/14/07
Posts: 884
Loc: Duncan, BC
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Quote:
This is a 100% crop showing the spike with the towel ring and camera lens at F2.8.
Thats an interesting variation hiro, very interesting. Have you got the companion 'slightly out of focus' shot to go with that one ? I'm really interested in seeing how the spikes change and move as you go thru focus with that setup.
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mikefulb
super member
Reged: 04/17/06
Posts: 165
Loc: Central NC
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I retried a new mask based on the nice web generator and it worked MUCH better than the one I'd designed myself in Photoshop. Even so at f/2.8 its very difficult to discern best focus - but much better than any Hartman style mask for sure. I use the mask to get close and then run the real-time CCDInspector curvature tool to determine when I've optimized FWHM across the entire frame.
What I found interesting was how the size of the pattern appears to shrink with wavelength. I don't understand the physics behind this phenomena but it was a surprise. The difference between my R and B filters was significant.
I wrote a small Maxim script to continuously grab frames and run an unsharp mask on the frame which aids centering as well. I also found using a line profile tool across the spikes let me determine with a high degree of accruracy when I'd centered the line.
Now I need to rig something up to swing the mask over the end of the scope remotely so I can stay in my office during the winter and still focus using this tool. I was thinking of using a gear retract servo for an RC plane which flips 180 degrees between two positions.
Michael Fulbright
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Michael Fulbright
http://msfastro.net
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Jerry3672
Vendor - Quantum Astronomy Products
Reged: 01/20/08
Posts: 496
Loc: Lexington NC
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Interesting Mike.
Do you think it is possible to use you mask and adjust the distance of you R and B filters to make them par focal? 
My other hobby is RC planes. I'm thinking 125 oz servo with metal gears. You could also swing the RGB filters with another channel. 
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Meade LXD75-SN-8, SN-10, C11
DSI Pro
Canon XSi 450D unmod
www.spike-a.com Bahtinov Style Focus Mask
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hiro
sage
Reged: 07/17/07
Posts: 386
Loc: Tokyo
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Thanks Dennis Sakve,
I could be confident about focussing for the first time with these tools.
groz,
I did not try out-focus images that night, though I saw the movement of the line the other night.
I use Vixen 4x12mm monocular on camera finder usually to confirm focus, and the focus was perfect at first touch with it that night.
In my preliminary trial with a simple tool made of three injection needles, I could see out-focus images as above.
We can see that the position of the horizontal diffraction line differs according to focus and wave length.
It is difficult to achieve fine focus with my monocular in short lenses, but it became easier with the tool.
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hiro
Canon EOS 5D / EOS 5D-AP / EOS 5Dmk2 sp2 by Seo san
Takahashi FSQ-106ED with reducer, extender, and "hiro design" off axis guider
Takahashi EM-200 temma 2 jr
Kenko Skymemo-R
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Nocturnal
scholastic sledgehammer
Reged: 09/14/05
Posts: 870
Loc: CT, USA
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Hi Michael,
I've also been pondering the possibilities of flipping this mask in front of the OTA automatically. The same mechanism could also be used to cover the scope at the end of an imaging session. Frankly it's a bit surprising that something like that doesn't exist although I'm sure it would be $$$. Instead of servos I was thinking either a stepper or a simple DC motor with a micro controller and end position switches. Servos are a great option too though, good idea.
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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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helmutoil
newbie
Reged: 09/13/08
Posts: 1
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Im new on here and im just starting on the big learning curve of astrophotography! I couldnt focus properly untill I read this thread! WOW it works! It just so happens I own a Laser cutting business so it was quick for me to cut a 3mm Black acrylic mask based on the orinal formula for my 8" SCT. Thanks for the advice guys top site!
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cvedeler
Carpal Tunnel
Reged: 12/20/05
Posts: 1896
Loc: Scottsdale, AZ
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Here is a Youtube video I made tonight showing how moving from inside focus to outside focus looks like with this mask. The difference between one extreme to the other was about 1/8th turn of the rough focus knob of my AP160.
http://www.youtube.com/watch?v=OFZKBop0ILU
While my home made mask works OK, the rough edges do not produce a nice clean defraction line. Time to make a 3rd generation mask... While this is fine for really bright stars, I would like to be able to use my mask on much fainter stars so I wouldn't have to move my scope / camera to check focus during an imaging run.
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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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xumaxer
sage
Reged: 01/30/06
Posts: 204
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Hey guys,
I tried to make my own mask a few days ago but I used a too hard piece of plastic, so today I did it all over again but this time I used a black transparency film (forgive my english, but there are words just to specific for me).
I printed the mask out of FarmerDave's Generator and glue it to the black transparency.
Then I carefully cut the mask with an exacto knife. I then placed the OTA's dewshield over the mask's back side and cut a strip of that foam campers used to sleep on and got the ends together.
After that I wrapped it around the dewshield (just tight enough)and had a few drops of glue on the mask and around the dewshield. Time to slide the foam over the shield and make contact with the mask. Voilá!
I tried it on Arcturus and Jupiter. Dead on!
One thing though: I tried it on my 350D and.... forget it! It's just too dim! 
I tried it on Jupiter with my DMK21AF04.AS at f/6.9 and f/13.8 and it was just spot on.
Next step will be making one for my C11.
Can't wait to get my hands on my still to arrive ST2k...
xumie
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Ciao
xumie
________________________________
C11
FS-102NSV
G-11 Gemini
ST2000XM + CFW10
DMK21AF04.AS
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