CHriss But "best" is most relative here, a RMS of 0.8 to 0.9 certainly is nothing to be happy about, especially taking the price of the AM5 into consideration.
As I have mentioned many times, a typical worm geared mount will outperform (w.r.t. autoguiding) a strain wave geared mount that is at least 3 times more expensive. The price of the strain wave gear mount has nothing to do with guide performance (and ZWO may be worse than folks who know how to machine precision mechanical parts); you are paying for other conveniences (such as portability) and not precision.
No one should ever buy a strain wave gear mount if they don't understand that price performance aspect of stain wave gears. Don't listen to the YouTube shills, it is not their money; and you never see a YouTube shill tout a 10Micron mount, have you? That should tell you something.
That being said, if you are getting 0.9" typically and ZWO advertises on paper (or web page) that you can get 0.7", that should be enough to return it and get your money back. Even if 0.9" is good enough for you -- you did not get the mount that you had paid for. If they use weasel words such as "typically 0.7", then keep that in mind the next time you need to buy something ("fool me once, shame on you, fool me twice, shame on me").
Just one note about the pixel size of the guide cam.
From the first guide graph that you showed, the large errors are not caused by bad correction pulses. It looks like a mechanical problem. So, not need to look at pixel scales etc. Look for lose bearings, bad belts, etc.
A telling point (which you did not mention earlier) is that the large error spikes are periodic. They occur every 110 seconds or so (you probably can do more work to get a better average using more cycles than is shown in the above graph).
Now, the problem with the above is that it happens on both the RA and the declination axes at the same time. They are independent and orthogonal motors. So, that appears to preclude the strain wave gears themselves as the source of the problem, but some mechanical defect in the rest of the ZWO mount.
Did you send the graph to your dealer? They should immediately refund the cost of the drive since there is something so obviously wrong from the large periodic spikes. If not, just dispute it through your bank/PayPal and do a stop payment.
The problem with the ZWO mounts so far is that everyone seems to have a different problem with it. The design does not appear to have been vetted by an engineer, with proper limits in place for QC to take defective products off the assembly line before shipping to customers.
Chen
