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Equipment Discussions >> Video and Electronically Assisted Astronomy

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treyk
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Reged: 12/12/07

Loc: Roswell Georgia
Help: A nasty little M42(SDC-435)
      #5587753 - 12/24/12 09:10 PM Attachment (84 downloads)

Got a new scope and I wanted to try some video imaging on it the other evening. This did not go so well. Attached is a screen cap of M42. Here's some data:

Seeing: Fair to good in suburban Atlanta

Platform: AT72ED on CGEM (go to was pretty good)

Cam modifications: Stock IR removed, Fan installed & wired remote

Optical train: SDC-435>blue fireball nose>GSO .5x FR>Orion IR cut>Orion Imaging Skyglow>AT72ED (no diagonal involved)

My gut tells me there is a problem in the optics here. I tried just about every adjustable setting on the cam and the problem remained as long as the object was visible. Im pretty confident in the focusing having used a mask though it took a really bright object to get the pattern to focus with. The best focus I could achieve was toward the end of the focuser travel though I can slide the nose out a bit and still have travel room to spare. I approximate that FR is around 57mm from the CCD chip.

Any suggestions would be appreciated.

Trey


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Ira
Carpal Tunnel
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Reged: 08/22/10

Loc: Mitzpe Ramon, Israel
Re: Help: A nasty little M42(SDC-435) new [Re: treyk]
      #5587757 - 12/24/12 09:14 PM

Star of Bethlehem?

/Ira


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treyk
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Reged: 12/12/07

Loc: Roswell Georgia
Re: Help: A nasty little M42(SDC-435) new [Re: Ira]
      #5587760 - 12/24/12 09:17 PM

Thanks Ira ... I knew I'd get an answer here!

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Ira
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Reged: 08/22/10

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Re: Help: A nasty little M42(SDC-435) new [Re: treyk]
      #5587766 - 12/24/12 09:23 PM



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StarStuff1
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Reged: 04/01/07

Loc: South of the Mason-Dixon Line
Re: Help: A nasty little M42(SDC-435) new [Re: Ira]
      #5587791 - 12/24/12 09:52 PM Attachment (47 downloads)

It kinda does look like a focus and exposing problem. Here is a pic I made almost two years a go with a 435 and a similar sized optic. Too many scopes to remember the exact one or exposure time...sorry.

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StarStuff1
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Re: Help: A nasty little M42(SDC-435) new [Re: StarStuff1]
      #5587797 - 12/24/12 09:54 PM Attachment (42 downloads)

OK, I can do a little better than that.

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StarStuff1
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Re: Help: A nasty little M42(SDC-435) new [Re: StarStuff1]
      #5587800 - 12/24/12 09:58 PM

Both are just quick point 'n' shoot screen shots. The scope was (I think) a 5.1-in f/5 newt.

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Martin Lyons
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Reged: 10/06/08

Loc: Cape Town, South Africa
Re: Help: A nasty little M42(SDC-435) new [Re: StarStuff1]
      #5587984 - 12/25/12 01:27 AM

Try without all those filters.
I suspect there's some sort of internal reflection interference going on between all those parallel surfaces.
Also, I have thrown away my GSO reducers because they introduced more distortion and abberations than I needed no matter where I had them positioned (both 2" and 1.25" versions)

Start with just the scope and camera and then introduce each additional component until the symptom re-appears.

Martin


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Dwight J
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Reged: 05/14/09

Loc: Lethbridge, Alberta, Canada
Re: Help: A nasty little M42(SDC-435) new [Re: Martin Lyons]
      #5588010 - 12/25/12 01:48 AM

I concur with Martin. I have the GSO reducer as well and it was not very good with the videocam, especially with the extension tube. The glow around the stars is the giveaway for internal reflections.

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treyk
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Reged: 12/12/07

Loc: Roswell Georgia
Re: Help: A nasty little M42(SDC-435) new [Re: Dwight J]
      #5588242 - 12/25/12 09:35 AM

Thanks ya'll will try that next and will post the result (as soon as the sky clears and the inlaws leave).

Trey


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GlennLeDrew
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Reged: 06/18/08

Loc: Ottawa, Ontario, Canada
Re: Help: A nasty little M42(SDC-435) new [Re: treyk]
      #5589113 - 12/26/12 12:33 AM

Wow! This has the appearance of a diffractive effect. As Martin suggests. Start simplest, and go from there in complexity re. the number of additional components. Sometimes, simply peering into the optical train from both ends when the camera is removed can supply clues. Point the scope toward a variety of light sources, a flashlight across the room being one possibility.

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Craig in Tacoma
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Reged: 01/27/11

Re: Help: A nasty little M42(SDC-435) new [Re: treyk]
      #5601143 - 01/02/13 12:09 PM Attachment (30 downloads)

I just had to say this is not typical of what you can produce with the Samsung and an AT 72mm ED telescope. I agree you may have too much in between the camera and M42. Here's a shot I took with no filters, the SDC435/Astro Tech 72mm ED, on an iOptron Minitower from 2.8 mag skies..You should be able to duplicate this easily with your set up.

Craig


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