Hi guys, new setup = new problems. I've adjusted all the settings appropriately on phd2 (switched from finder guider to ed80 for guide scope). drift align fine and guide ok. than after a few minutes id get this sudden rise in corrections. it'll settle again for a few seconds and spike again. It's not a balance issue, I dont think. Ive also placed vibration pads and its not that particularly windy. ive attached the phd2 corrections here, this is driving me insane. 3 days in a row where new problems arise and havent been able to get anything more than one picture.
Tony, how is the polar alignment? This can cause issues with the dec going crazy as can backlash. It doesn't take much breeze to move the output on the graph. I have an imaging run going at the moment and the occasional gust is moving the dec axis on an EQ6 pro with an ED120. Not enough to ruin any subs yet but I can see the movement in the graph. I am hoping it will calm down as the night progresses.
Hi brian, the polar alignment (last time i checked) was at around 1.7 arcsec of error. I've also rechecked the balance (it was off but when i checked the guiding again still same spikes). It also spikes when its dead calm and it looks like the spikes occur periodically that I can almost predict when it occurs.
As Peter said, it is most likely DEC backlash. You can see the correction pulses on one side "accumulating" before the correction starts. Then it over-corrects and the correction pulses "accumulate" on the other side.
Run the guiding assistant and measure backlash. It will most likely tell you to guide in one direction only.
Tony, in case you weren't aware of it, further to what Brisen said,
the scope should be balanced a little against the R.A. movement
in order to minimise or eliminate backlash. The same goes for Dec.
raymo
Thanks for the quick responses! I've packed up for the night after some frustration so I'll have to wait for tomorrow night to try out guiding assistance. Someone also suggested that the dec grub screw may be loose and need retightening but I'm scared of making things worse!
So things to try tomorrow, off balance a little on both axis, guiding assistance (didnt even know this was a thing :/ woulda been handy to know aha). Astroanarchy is coming up on saturday so hoping to get it solved by than so i dont waste another dark sky night
