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73518RE: RE: Guider/Imager Image Scale relationship help needed

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  • w0fly2
    Oct 30, 2013

      Thanks for the input Dave. I hear you as far as the names for processes in PixInsight!

      I have the Orion EQ-G and I know that it is a low end mount. Someday I'll upgrade. My goal is to see how well I can do with low end equipment. I've seen plenty of good images made on the EQ-G and I've had some luck but the guiding is driving me nuts. 

      I've come to the conclusion that it is the hardware, either the mount or the imaging train. One thing I changed that made an improvement was to unbalance the mount to the east. I was able to get nice tight stars at 300 sec and a little wobble at 600 secs. I also removed the Field Flattner and have everything mounted to the OTA via a threaded connection instead of thumbscrews. Unfortunately the weather stinks right now and I'm unable to test the change.

      My question about the Imaging Scale was based on the fact that my RMS is routinely .05 (I don't understand what that means exactly but I think that's good), the graph looks nice but still getting the oval stars. 


      PS I'm at that point where I need to decide which way to go to process my images. I have PhotoShop and Pixinsight and not very experienced in either. It's time to pick one method and learn it well !

      ---In ccd-newastro@yahoogroups.com, <ccd-newastro@yahoogroups.com> wrote:

      What mount are you using?  I'll share some of my experience.  If you have a paramount - just stop reading right here :)

      I struggled with guiding.  It seemed so simple, yet all my subs had oval stars.  I changed every software setting a million times and even asked this same question.  Turns out it was my mount (I was in denial for a long time).  What was happening was the mount errors were happening fast and the guider couldn't react fast enough.  A guider can easily guide out slow errors.  It's the fast transients that get past it.  So fast that you may not see it in the guider data very easily because they aren't represented in the data well. I spent hours looking at my guider error graphs.  Then I surrendered and realized my fork mounted LX200 just wasn't capable of taking a sub longer than about 300 seconds.  I bought a G11-G2 and plopped my rig on it (with a ring mounted guide scope - it doesn't move, but it should) and I can now guide at .1 RMS all night long with points for stars.  30 minute plus subs are the norm for me.  More than happy to chat on the phone if you want.  I'm pretty new too and the climb up the learning curve is fun and frustrating.  Now if I could figure out why the named things the way they did in pixinsight, but that's another story.

      Clear skies,


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