Horsehead from Utah

Hi all. I made a trip to Heber City last night, looking for some dark skies. I found some. At any rate, I imaged the Horsehead and Flame nebulas, and they turned out OK, although my framing sucks! Here is the image.

I didn't notice last night, but I think the nosepiece may have been mounted a little bit crooked, because the stars on the left are not as focused as those on the right.... DANG!! It is odd that I looked at every image that came off the camera, while sitting in the cold last night, but didn't notice the problem until I tried to process the images this morning. This hobby sure has a lot of things that can go wrong!! :S Oh well, it was fun anyway.

Can someone suggest a way to get the focus right? It is much tougher than I thought it would be to do it manually. Any help would be appreciated.

Comments and suggestions are always welcomed.

Cheers,
Tyler

Scope: Takahashi Sky90 with Tak Field Flattener
Mount: Losmandy G-11 with Gemini Level 3
Camera: SBIG ST2000XM
L:R:G:B image - 5:5:5:5 minutes
Acquired using MaximDL 4
Processed in MaximDL 4 and Photoshop

Attached Image:

That's a very nice image, Tyler, especially for your exposure times.
As far as focusing goes, a Hartmann mask would help. The Tak 10:1 microfocuser might make things easier, too. To get really accurate, you would probably need to get automated. The RoboFocus works well on the Taks because it goes on the rack-and-pinion shaft. I believe some of the thinner focusers (like the DF-2?) that go in the optical train also work well.
The Hartmann mask costs $0, a rarity in astro equipment. You might want to try that one first.

dan kowall

Very nice job, great exposure.

I also recommend the 10-1 microfocusser, it does make things easier.

Instead of a Hartmann mask, I use string held in front of my objective in the shape of a "+". If you're out of focus, you'll see two vertical and two horizontal diffraction spikes. As you get closer to focus, the spikes will merge into one. You are in focus when the spikes are brightest and longest.

In conjunction with the diffraction spikes, I also use Images Plus and its FWHM Focus mode (DSLRFocus also has this capability). The combination helps nail down critical focus.

Even with all that, I still manage to miss focus from time to time :-(

Nice shot, Tyler. You got a lot of signal for the short time! The Sky90 looks like a great scope.

I also recommend the diffraction focusing method Don described. A motor focuser helps because you don't have to touch the scope and it can be automated.

For a good, but dated, basic focusing tutorial do a Google search on "Bill McLaughlin" Pick his Images from the Night Sky page and click Information then Focus Techniques under Tutorials. I would give you the link but IIRC we're not suppose to add links here???? I'm sure there are others but I remember this page.

Nice shot - Cal

That's one BEAUTIFUL image Tyler! 8)
Wonderful detail & colors!

Thank you for sharing with us!

Hi all. I was not vey happy with my first effort at processing this one. I think I tried too hard to make the sky jet black, and it really hurt the image. Here is another attempt at processing the data. What do you think? Is it better?

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