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1. since i am the owner of an 8'' dob and i am starting astrophotography with an heq5 pro mount do i need this mask for focusing or is it only for SCTs, MACs etc?

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hi i'm new to this forum and i followed this link from another forum. my questions for this mask are two


2. the angled bars are at 40 degrees from the center of the of the mask or 20 degrees (i saw this value at another forum)

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So, I have received many requests for the scalable vector graphic drawing I did for the Bahtinov Mask. So I figured I would post the 'email' I was sending everyone and include the actual files here so anyone can download and use them. Please do not use my drawings to produce masks to sell. These drawings are provided to the community as open source and should always be treated as such.

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Hello!

Thank you all for waiting. I must apologize in advance. I had made a mistake in the asking the size of aperture on each of your scopes. I actually needed the full front diameter of your scopes so the mask can sit in front without leaking light in through the sides. I suppose it isn’t that big of a deal but I also didn’t want to send you a useless size.

So I have included the scalable vector drawing that I made. This way you can simply scale it to the exact size you need with out waiting. You will need to download and install Inkscape if you haven’t already. Alternatively you can import the file in to any other editing software that supports svg files (scalable vector graphics) such as Corel Draw.

In addition I have included a new drawing I did that is more designed for refractors. The central obstruction is greatly reduced to allow more light through. Please let me know how it works out if you try it.

Once you have Inkscape installed simply open the svg file. Select the arrow tool in the upper left side and click on the mask. On the far right side of the measurement boxes near the top middle of the screen, change the ‘px’ selection to ‘mm’ – this is your measurement unit. Next, in the right two measurement boxes, enter in the diameter of your scope opening. Enter the same number for both boxes so your mask is a perfect circle.

Click on “File” and export your resized mask as a bitmap. This will allow you to more easily print out your new pattern from your preferred printing program. Here is a screen shot with the items I just mentioned circled.

That should get you a nice new mask to try out. Whether you print it out on paper and cut it out or you have one cut for you, please let me know how it works out for you! Please let me know if you have any questions!

Cheers!

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As someone else posted you will still see some diffraction spiking from the spider but the Bahtinov Mask diffraction spikes should still be very easy to see for focusing. You will just have some extras in there.

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Thanks Adam. I should have looked closer to the other posts to find my answer. I must have put isramirez to sleep. Not sure that was most polite way of comming across, but anyway...

I'll look up the program to download the scaled template.

Thanks again.

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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I think you can contact him, here's his account page with e-mail from the Russian forum
http://www.astronomy.ru/forum/index.php?action=profile;u=408

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We didn't have any luck with his email directly. Not sure if it was a firewall or what - Jerry finally signed up on his forum and translated everything into Russian! Very creative!

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John Wunderlin
Vendor - Spike-a Bahtinov Focusing Mask
Empire Ranch Observatory
Iowa County Astronomers

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