Even more guiding problems

[Astrofriend]

Hi,

Maybe this can give some tips.

 

My mount is a EQ6 Synscan mount but I don't think there is very much different compare to yours and I also have to take my mount apart and regrease. But still my total rms error normally is in the 0.8" rms range and my guidning curve didn't look like yours. I almost have the default parameters, later I adjusted the pulselength (I connect it over EQMOD, not ST4) only adjusted the pulselength from 1000mSec to 1500mSec. And I also adjusted the camera angle to align with the RA and DEC axis carefully. Backslash compensation is on.

This is a typical curve when it perform good for me (before I adjust the play in axis and the mount is not modified in any part):

When telescope pointing in some direction it's much worse, maybe 1.5" rms error totally. I have off-axis guiding with an old QHY5 camera and my telescope has a focallenght of 682mm f/5.3.

 

Our setup isn't too much different. But you guide with the guide telescope and that has much shorter focallength, maybe 1/4 of the main telescope focallength? Earlier when I guided with a guide telescope my focallength relation was about 1/2. My mainproblem then was flex between main telescope and guide telescope, have you checked your equipment about this? But I think your problem is more related to mechanical problem and maybe you allready have found the problem with the defective roller bearing. How about the noise on the star you guide on? I try to have it better than s/n=8.

 

After that I have adjusted the backslash in RA & DEC axis. Now it's alomst zero where it's tightest and when I revolve the axis 180 degree where I have the biggest backslash I can bearly feel it. Maybe a bit too tight and I get problem in cold weather and have too increase it a bit. I will test it soon, just waiting for a clear sky. My biggest problem was the backslash in DEC axis as it's normally.

Now after adjusted the backslash I hope to reach the 0.5" to 0.6" rms error range. But still no modification to the mount so maybe a bit optimistic. I also use dithering and have to put long delay to let it stabilize, even that I hope to get faster after my adjustment.

 

About the polar align and how important it is. I use drift align and I have written down an instruction how to use it with PHD2, maybe helpfull:

http://astrofriend.eu/astronomy/tutorials/tutorial-drift-align/tutorial-drift-align.html

 

/Lars

[dyfiastro]

Thanks for the replies everyone.
 

To be honest I am not now sure what the issue is.
I have rebuilt it again and now I have the belt off etc... I can actually feel just how bad it is still.
Not knowing enough about this type of thing and how to go about correcting it I think I am going to opt to send it away for professional repair and a tune up.
At least once it comes back I know its going to be good.

Thanks again everyone for all the help and advise and I will post an update once I have had everything sorted and report back.