I want to find a solution for the first issue, because it has been bugging me ever since I got my current equipment about a year ago. I’ve already read a lot of threads about these jumps, and I think I’ve done as much as I could possibly do to minimize these jumps. Besides having relubed my mount, and in the process eliminating as much backlash/slack as possible, I have taken the following precautions:
1) Polar alignment procedure via my mount. This is accurate enough not to cause significant field rotation, but is sufficiently inaccurate to ensure a little drift in the DEC, so I can guide the DEC north only or south only, which keeps constant traction on the gears.
2) Make the RA axis a little east heavy, and the DEC axis back heavy (i.e., just a bit more weight on the camera side than on the corrector plate side). Again, this should ensure constant traction between the gears on both axes.
Now, I’m only using a C6, a Rebel XS / EOS 1000D DSLR and an Orion SSAG autoguider, the combined weight of which should be well within the operational limits of the CG5 mount. Yet, I still manage to get these jumps during guiding. What’s causing this? Does the fact that M51, when passing through the meridian, for me is almost right above me in the zenith, have anything to do with these spikes? Have I inadvertently made the imbalance on my axes too big? I only move the scope and the counterweight about 1cm (or just under half an inch) away from what I perceive to be the point of balance. Those of you who use this mount as well, do you preload your axes, and if so, by how much?
For those who want to see my guide logs, please see the links below. The first run was to determine whether to guide north or south on the DEC, and the last 3 to 5 runs I experimented a little with some settings, like dec algorithm, and aggressiveness and hysteresis combinations. But everything in between is ordinary guiding with the same settings used throughout (except after the meridian flip, when of course I switched between north only and south only dec guiding).
I really hope someone can help me combating this issue. Thanks to anyone who can offer any advice.
Guide log 1: http://www.mediafire.com/?jjeujy22mmy
Guide log 2: http://www.mediafire.com/?yjny3yii2wz
Bear in mind that guiding was done at 950-1000mm, which, with my setup, equates to a resolution of approximately 1.0 arcsec/pixel for the SSAG.