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Equipment Discussions >> Mounts

Pages: 1
Stew57
Carpal Tunnel
*****

Reged: 05/03/09

Loc: Silsbee Texas
Guiding Problem?
      #5482463 - 10/21/12 06:14 PM

I have been guiding my CGEM C11 with the celestron guidescope 80mm F7.5. The DEC is very good but I do get some elongation in the RA axis.





The graphs are pretty much the same for all runs. There is always a spike at the same place in the frequency spread. it appears at the 8/3 pe error location, the rest of the errors are random and change between imaging runs. Is this because the 8/3 PE error of my mount (runs about 75% of the worm PE) is too hard to guide out?

I am using my setup for live video work and have just started guiding. The mount cannot be used for longer integrations without guiding.


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orlyandico
Postmaster
*****

Reged: 08/10/09

Loc: Singapore
Re: Guiding Problem? new [Re: Stew57]
      #5482898 - 10/21/12 11:45 PM

hi Mark

Looking at your guiding graph that's about +/- 0.8" - or is that +/- 0.8 pixels?

If it's already in arc-seconds, then you aren't gonna get any better than that.

I bet your RMS is less than that, maybe 0.4" ?

That sort of performance is as good as it's going to get. I think guiding a C11 tightly on a CGEM is... not really doable. Try using a reducer..

Alternatively, try an OAG. Might help. Tighter guiding intervals too. Metaguide? Frank says sub 1" is consistently possible with MG on CGE-class mounts.


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orlyandico
Postmaster
*****

Reged: 08/10/09

Loc: Singapore
Re: Guiding Problem? new [Re: orlyandico]
      #5483537 - 10/22/12 12:11 PM

Hi Mark,

Post my miraculous CGEM resurrection, here is a guiding graph I took (the guider is a 50mm guidescope). But you can see my residual PE and the largest is also the 8/3. Interesting that the fundamental is so tiny it's lost in the noise. But then I have an Aeroquest worm.



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orion69
scholastic sledgehammer


Reged: 05/09/10

Loc: Croatia
Re: Guiding Problem? new [Re: orlyandico]
      #5483734 - 10/22/12 02:06 PM

If you manage to get decent images with C11, then you have really exceptional CGEM mount.
But I don't think you can manage that without OAG (flexure).

Knez

Edited by orion69 (10/22/12 02:06 PM)


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