SteveD Correct me if I am wrong but I am assuming that you are using the S50. 95% capture rate for M42 at 60sec exposure is phenomenal in my experience. For comparison I am using the WO wedge on the ZWO TC40 tripod and 30sec subs. I level the tripod and pre-align to the NCP during the day. While I do not re-calibrate the compass and accelerometer every time, I did re-calibrate both before I took a sequence of images over a group of recent clear nights, not moving the scope between sessions. Unless I am doing an experiment I always PA to 0.0/0.0 and once I get that I have the SS App verify it by repeating the measurements without making any adjustments 2 more time. I have only once had it not repeat in which case I re-do the alignment until it does. Also, I have re-checked the PA after a few nights and it still reports 0.0/0.0 so it stays well aligned.
So, with that setup and procedures I have gotten capture rates for M42 of 55%, 49%, 37% and 47% on very clear moonless nights with no noticeable wind and good seeing.
What latitude are you at? The PA error depends upon the alignment errors in Alt and Az. The Az error depends upon the cosine of the latitude. If you are at a high latitude then your setup may be significantly less sensitive to Az errors and only depend upon your Alt error. I am at lat 38 deg which makes me sensitive to both.
