Unpredictable guiding with a 600e Goto


Tom Blahovici
 

Hi,

I am trying to come to grips with strange guiding behavior using my 600e (with the CP2 controller and latest roms etc).  I am wondering if perhaps I am not balancing the mount correctly for example.  The camera is an STL11000 with a Tak FSQ106.  The pixel scale is 3.5 arcs/pixel and I am using TheSkyX for autoguiding.  The mount has been polar aligned with PemPro to within 20 arc seconds of the pole in both az and alt.

Now in general it seems to be working with pulse guide and a rate of 1 and the aggressiveness has to be all the way down to 1 which means it is hardly doing anything.  At times however, changing position of the telescope (same side of the meridian and maybe 20 or so degrees away) will result in one direction of guiding continuing to increase with the corrections doing nothing.  To have it guide, I need to increase the aggressiveness higher in this direction.

If I decide to use an overall higher aggressiveness then the guiding will have a strong sawtooth pattern of over 1 pixel.

BTW I usually take 3 to 7 second exposures of the guide star.

I am wondering if balancing has something to do with this.  I keep the balance around the polar axis so that when the telescope is on the west of the meridian, the balance is heavier on the counterweight side.  I never image on the other side of the meridian since I have trees there. The Dec balance is kind of tricky.  Where should it be? Perfectly balanced?  How does one do this since when the clutches are released there is quite a spread of balance points.

As to the backlash, it was adjusted a while ago using a dial gauge and was as small as possible without causing any binding.

Any hints would be great.

Tom



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