Drift Align oddity

[WingnutR32]

Hey IIS members,

I was just in the process of redoing my alignment on the AZ-EQ6-GT mount and noticed a strange occurrence.

Now I have usually followed the same process without an issue:
- Align with Alignmaster (3 iterations)
- Drift align with PHD making minor correction
- Double check with CCD Drift Align

Now, Alignmaster was pretty happy with less the 1 arc second inaccuracy. PHD was giving odd results in dy, drifting both north and south (doing elevation) in BIG sweeps, rather than the normal back and forth along the center line.

CCD Drift essentially confirmed the big sweeps seen in PHD, a really weird bow in the drift. (See attached 120sec exposure, moving north for 60sec, south for 60sec).

If I do a 2 min unguided exposure, it is definitely wrong, as the drift appears huge.

[Peter.M]

You might be overdoing it a little. With 2 iterations of align master I can expose for half an hour and get round stars. Whatever it is I doubt that it is related too your polar alignment.

[WingnutR32]

I usually can also, Peter. Just not sure why tonight is being different to previous nights..

I have never seen a CCD Drift align result with a bowed line which near on finished back where it started.

Edit: I have redone the drift align again and have confirmed that my polar alignment is good. So there is something else going wrong in my sidereal tracking perhaps that is causing terrible stars in 2-3 minute exposures.

Another edit to avoid double posting: I just had a brain fart / lightbulb moment... I have a really odd inkling that I may have forgotten to balance the scope when I put it back on the mount after changing the rubber vibration pads. This is going to be a strain on things if it is out, surely.

[WingnutR32]

Ok, I checked my OTA balance and all is fine there. So it must be something else.

I did a guider calibration in Maxim DL and noticed that I am not getting an L shaped pattern. Have a look at my poor mspaint drawing to see my broken L shape.

Any idea on what causes this?

Also, I ran Pempro last night and it would appear that I have 25 arc second peak to peak with PEC off and after creating a curve and sending it to the mount, turning EQMOD PEC gain to 1x, I had no difference. Even after inverting the curve, there was no change in my peak to peak, at one point it got worse. I'll have another play tonight with it, but this doesn't make sense why.

[WingnutR32]

Bump. Ready to sell all equipment, 4 superb nights wasted.

Can anyone provide some info on what causes a guider calibration to produce an L Shape without a 90degree angle? (See above for picture)

My OTA balance has been redone again, Dec first and then RA... The slight repositioning of my OTA has cleared out nearly all my Dec backlash.

PEMPro still won't provide a suitable PEC, yet I have clearly 4 re-occuring mechanical movements. The instructions are not very clear at all.

[WingnutR32]

And just for reference, I am seeing the same behavior as Steve in this thread when I calibrate PEMPro:
http://ccdware.infopop.cc/eve/forums/a/tpc/f/401101098/m/3637086826