Jump to content


Photo

Help: A nasty little M42(SDC-435)

  • Please log in to reply
11 replies to this topic

#1 treyk

treyk

    Sputnik

  • *****
  • Posts: 40
  • Joined: 12 Dec 2007
  • Loc: Roswell Georgia

Posted 24 December 2012 - 09:10 PM

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. I’m 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

Attached Files



#2 Ira

Ira

    Mercury-Atlas

  • *****
  • Posts: 2625
  • Joined: 22 Aug 2010
  • Loc: Mitzpe Ramon, Israel

Posted 24 December 2012 - 09:14 PM

Star of Bethlehem? :)

/Ira

#3 treyk

treyk

    Sputnik

  • *****
  • Posts: 40
  • Joined: 12 Dec 2007
  • Loc: Roswell Georgia

Posted 24 December 2012 - 09:17 PM

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

#4 Ira

Ira

    Mercury-Atlas

  • *****
  • Posts: 2625
  • Joined: 22 Aug 2010
  • Loc: Mitzpe Ramon, Israel

Posted 24 December 2012 - 09:23 PM

:rofl2:

#5 StarStuff1

StarStuff1

    Soyuz

  • *****
  • Posts: 3874
  • Joined: 01 Apr 2007
  • Loc: South of the Mason-Dixon Line

Posted 24 December 2012 - 09:52 PM

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.

Attached Files



#6 StarStuff1

StarStuff1

    Soyuz

  • *****
  • Posts: 3874
  • Joined: 01 Apr 2007
  • Loc: South of the Mason-Dixon Line

Posted 24 December 2012 - 09:54 PM

OK, I can do a little better than that.

Attached Files



#7 StarStuff1

StarStuff1

    Soyuz

  • *****
  • Posts: 3874
  • Joined: 01 Apr 2007
  • Loc: South of the Mason-Dixon Line

Posted 24 December 2012 - 09:58 PM

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

#8 Martin Lyons

Martin Lyons

    Messenger

  • *****
  • Posts: 409
  • Joined: 06 Oct 2008
  • Loc: Cape Town, South Africa

Posted 25 December 2012 - 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

#9 Dwight J

Dwight J

    Apollo

  • *****
  • Posts: 1012
  • Joined: 14 May 2009
  • Loc: Lethbridge, Alberta, Canada

Posted 25 December 2012 - 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.

#10 treyk

treyk

    Sputnik

  • *****
  • Posts: 40
  • Joined: 12 Dec 2007
  • Loc: Roswell Georgia

Posted 25 December 2012 - 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

#11 GlennLeDrew

GlennLeDrew

    Voyager 1

  • *****
  • Posts: 10665
  • Joined: 17 Jun 2008
  • Loc: Ottawa, Ontario, Canada

Posted 26 December 2012 - 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.

#12 Craig in Tacoma

Craig in Tacoma

    Vostok 1

  • -----
  • Posts: 118
  • Joined: 27 Jan 2011

Posted 02 January 2013 - 12:09 PM

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

Attached Files








Cloudy Nights LLC
Cloudy Nights Sponsor: Astronomics