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Making your own Hartman Mask


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#1 swholden

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Posted 02 April 2008 - 10:06 AM

I found this really nice sight that will aid in making your own Hartman Mask.

http://billyard.serv...m/Hartmann.html

Just put in your dimensions, and it will generate a template that you can print and use for your cut outs.

Haven't made mine yet, but plan to in the coming days.
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#2 Fish Cat Fish Dog

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Posted 02 April 2008 - 11:49 AM

Great job finding this site.  Thanks.

#3 Tony

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Posted 02 April 2008 - 03:04 PM

Cool template! is it better to use the triangle shapes or circles? Thoughts?

#4 swholden

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Posted 02 April 2008 - 05:03 PM

Not sure which is better.
I think with the triangles, you get defraction spikes. (I think I read that somewhere)

Just pick up some materials to make mine.
Picked up 2 needle point rings (@ $1/each).

I want to make 1 Hartman and 1 defraction to see which I like better.
Using Mark Siboles idea of using 1/4" dowels for the defraction mask. (That was $.29).

My plan is to make the Hartman out of heavy paper. Test, and if all is well, use that paper as a template to make the mask out of a heavy dark plastic or very think plywood. Both of which I have.

This way it will be durable and look nice. It's all in the look you know.

I'll share my findings when I'm done.
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#5 Dave

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Posted 03 April 2008 - 03:59 AM

I can't get the link to work.

I tried in both IE7 and Firefox.

#6 swholden

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Posted 03 April 2008 - 04:50 AM

I just tried it and seems to be working.

Are you getting a pop up message at the top warning you about any scripts that may be running?

What message you you seeing?
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#7 Dave

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Posted 03 April 2008 - 06:27 AM

It works fine now.

#8 swholden

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Posted 03 April 2008 - 06:34 AM

Great!
Let me know how you make out.
I'm making mine right now......(it's slow @ work today).
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#9 Tony

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Posted 03 April 2008 - 07:13 AM

Easy mask... I have used black foam core board, can cut with a matt knife, and use duct tape to "tack it to the scope dew shield. I put one layer on the mask itself to protect the surface from coming up when you put a second layer on it to attache to the scope. fold the end over so you have a place from which to lift it. that way you can stick the "flaps" of tape down on the mask when not in use, and pull them up to attach to the scope. This way I have made masks for my several scope diameters and digital camera lens. The masks are flat so you can easily stack them in a plastic food bag for save keepng and dew protection.

good template!!

#10 swholden

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Posted 03 April 2008 - 07:45 AM

I've printed a few templates, using different mask aperatures and spaced differently. Not sure which would work best. I have an ETX 125.

Using a piece of cardboard first, before making something more permanent.

Also making one using 1/4" dowel.

If time permits, I'll share photos when complete.
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#11 swholden

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Posted 03 April 2008 - 09:23 AM

So here is what I have.

I can't believe I forgot my glue @ home, so can't glue my little sticks together and onto the ring.
I'll do that when I get home.
It should have time to set before dark.

The card board is just a test. For some reason it just doesn't look like it would work. Like the triangles are too small.  Or too close to the center. I don't know. We'll see I guess. :)
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#12 akjudge

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Posted 03 April 2008 - 10:16 AM

Keep the details and results coming.  Alot of us are interested in how it works out.
Jim

#13 swholden

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Posted 03 April 2008 - 10:29 AM

Will do.
Tonight will be "first light" for both of them :)
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#14 Fish Cat Fish Dog

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Posted 03 April 2008 - 11:45 AM

I built one with triangles.  I just need to move some clouds.

#15 swholden

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Posted 03 April 2008 - 12:01 PM

Sounds like it's going to be a "mask-a-thon" tonight.
Be sure to share your results.
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#16 Dave

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Posted 03 April 2008 - 12:53 PM

I made one a few years ago using two triangles and it worked (still works) just fine.

From my experiences you don't have to be too precise, they all seem to work.

#17 swholden

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Posted 04 April 2008 - 04:59 AM

Ok, no pictures to share, but here are my thoughts.

Viewing over all last night really stunk. Thin cloud cover, but you could see a lot.
Cold, somewhat windy. It came in bursts that it just made viewing poor.
And couldn't get the scope to track worth anything.
Also just couldn't get Saturn centered in the imager. Either too far left/right/top/bottom, and of course at the magnification and minute moves you make shoots the object right off the screen. :)

But, my hartman worked well. I think I need to make the holes a bit bigger to let more light in for easier viewing and focusing. Didn't try it with a camera since it was hard to see with just an eye piece.

My diffraction masked worked very well using an eye piece. I was very happy with it. Tried it with a camera and made no progress. But that probably was due in part that after 2 hours of trying to image Saturn again and getting frustrated, I just wanted to test this mask with an imager and see how it worked.

I'm sure it will, just need to practice/use it more.
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#18 karemrazim

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Posted 05 April 2008 - 01:25 PM

What is the rule of thumb for the seperation value of the holes/triangles?  I was looking at the website link from the first posting, but, other than the actual scope dimensions, not sure what to put in for the rest of the requested info.  Thanks.
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#19 swholden

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Posted 06 April 2008 - 03:55 AM

I wasn't sure either, so I made a couple different templates and used the one that put the holes in the center between the center mirror and the inner edge of the scope.

I works, but I think my holes are too small and doesn't allow enough light in.
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#20 Tony

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Posted 06 April 2008 - 04:02 PM

compared one with triangles to one with circles... triagles are most helpful as you can alight the spikes to get a sharp focus easily. Used on ETX 125 for imaging scope and SV102 for guider... both seemed to work great for instant focus confirmation using triangles. Using teh circles requried me to reduce the gain to get smaller spots to align, but the spikes from the triangles seemed to be really positive on focus.

thanks for sharing this neat tool




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