Hartman mask

[Orion]

On the 17th Jan there was a thread posted by Paul R on the Hartman Mask and after reading it I decided to make one myself, tell me what you think.

[iceman]

Great looking mask! Have you tried it out yet?

What's it made out of?

If you've got progress pics and want to do a writeup of making it, it'd be a great addition for the "Resources->How To" section on the website!

[[1ponders]]

Now that looks solid.:) I'll be interested to see images of your diffraction spikes when focus to see if they differ from mine. The layout of your triangular holes is slightly different to mine. (see image). I've thought about making one with the points of the triangles pointing directly to the center like your lower triangle to see if that makes a difference.

What have you made yours out of? I gather the mask is on your 18" Obsession. That must be fun to reach to get the mask on and off.

[Striker]

For some reason these masks have a close resemblance and are as scarry as my wife.....http://www.users.on.net/~striker/toilet.gif

[iceman]

:rofl:
I take it she doesn't read the forums :D

[Orion]

The mask is made out of that black cardboard that you get in the news agency, its used for school projects so my kids tell me.
Being a big mask I had to put some stiffeners on it for support
I have a platform that I hop on when I'm observing so slipping the mask on and of won’t be a problem.
Having limited time because of work and the weather not cooperating I haven’t chance to try it out.
The next time I do another project I’ll remember to document every step so I can put it on the forum.

Ps:There's no resemblance to the wife. Actually the mask looks better! sshh:D

[[1ponders]]

Ed, if you get the chance would you post an image of the diffraction spikes. I'd seriously like to compare any differences, with the aim of improving the design.

[Orion]

No problem, Just as I am typing this it started raining again oh well tonight is out of the question.:mad2:

[[1ponders]]

yes:( WE have to talk to someone about that.

[Starkler]

Oh so its not a template for a halloween pumpkin ? :D

[rumples riot]

Nice mask, I would also like to see the diffraction spikes also, as I am using the same type of mask, I must say though even the spikes are a little hard to see on the laptop screen.

BTW Paul how do you collimate your scope. I got mine down to infocus and is still a little out with the ring around the star not quite making it. Out of focus is fine with as small an airy disc as I can get 1 ring. But I am still getting a blue cast and red cast at opposite ends of my images. Do you get this, or is my collimation still wrong. Also I did notice that when I put the barlow in the collimation does look a bit out, just wondering if I have to buy a aprochromatic Barlow, thought I had one of those, made by meade. Hmmm, need to check that.

Anyway, if you could get back to me that would be great.

[[1ponders]]

Paul,
I do get a slight cast, I believe this is due to the slightly different refactivity of red and blue light, though that is only my assumption. I don't think you need an apo barlow. I start with just the ToUcam and get it as close as I can see, then pop in a barlow and repeat. I've tried it with a second barlow (unfortunately not a very good one) but if the seeings not very good it's just a mess. I was reading the other night on CN about this process and it was suggested that seeing needs to be pretty good to get it spot on. I've had a bit of a search over there but I can't seem tofind the thread now.

As for seeing the spikes, maybe try upping your gain and brighness a bit then reducing it after you've slewed to your target.

[rumples riot]

Thanks for the feedback Paul, really helpful. Might do a search on CN's for that thread myself. I will try the tip on the upping the gain and brightness to see those spikes.

regards

[Orion]

I came across this site it might interest some.
http://www.astrozap.com/pages/caps2.html

[[1ponders]]

Thanks for that Ed. Looks like I'm on the right track. Wish I had his seeing conditions though. My out of focus triangles aren't quite that crisp :P.

Paul I'm trying a few modifications to the mask at the moment and I'll post how they work out when I get the chance to use them.

[iceman]

Document the process, with words and pictures! Need it for the how-to guides on the site.

[[1ponders]]

Will do Mike