dciobota One thing I heard rumored is that the next firmware update will increase the min move from 0.1 pixel to p.2 to solve some guiding issues. This is very bad news for me and others that use small guidescopes to guide larger scopes, especially with strain wave mounts like the am5.
You probably were not around when ASIAIR had defaulted to 0.2 pixel as the MinMo. I found that 0.2 pixel was not appropriate for the RST-135 and sent in the reasoning behind it to Sam (I need to check my email if that was in 2019 or 2020). At that time I also had suggested an Advanced window to expose such adjustments because things like MinMo, LPF, and hysterysis are going to be different for different people. After at least a year, they finally relented and changed it to 0.1 pixel. But they refused to create an Advanced window for fear that it would confuse the typical ASIAIR user.
We will see if they keep being pig headed about Advance windows (not just for guiding but for everything else in ASIAIR).
By the way, to get any real response to a feature request, first establish yourself as a credible technical person, and then write directly to their people. Things posted to this forum get ignored more often than not. I have been sending advices to them (and also gets questions from their developers) for many years now. (Notice the purple lightning bolt in my avatar; I did not put it there :-). The strain wave mount and the dual sensor camera are among my recommendations in just the last couple of years -- ask Sam if you don't believe me, even though I still have reservations that ZWO can pull it off properly without lots more studying.
One suggestion in the last two years that they had absolutely refused to entertain is to use single thin USB-C cable to both power the camera (USB-PD) and transfer data very fast (USB 3.2) with a single light connector (as less problem with gravity). I noticed in the last month that a different manufacturer has started doing just that (and getting blazingly fast frame rates), so they may yet change their mind.
P.S. the reason the 0.2 pixel MinMo is bad for mounts with large periodic error slopes is that, unlike smooth worm geared mounts, is that the 0.1 pixel error is very likely to be a real mount error. It is common for a strain wave gear mount to continue to make more movements that are greater than 0.1 pixels in a long sequence -- as long as the slope remains large for a couple of seconds (not as likely for worm gear mounts).
And, as you said, that 0.2 pixel can correspond to large errors (in arcseconds) when projected to the sky.
If you don't correct that 0.1 pixel right away, by the time you take the next guide frame, it would be 0.2 pixels off by then. It is much better for a strain wave geared mount to make the correction right away before it starts running away from you. Say good bye to guiding better than 0.5".
Not just strain wave geared mounts, but even Avalon recommends a MinMo of zero pixel for the M-zero mount (i.e., always responds to every correction, no matter how small).
The reason for larger MinMo is to avoid correcting rough and noisy gears (often with no belt) in cheap mounts (like avoid correcting wind gusts). Strain wave gears are meshed at multiple places and should not be gitchy.
So, there you go, one more off topic posting in this thread (with apologies to Kevin, who is used to it by now -- you should see some of the exchanges between us on other threads :-). [Hey @Kevin_A , I should have enough parts to do a systemic study of the ZWO fan vibration later this week; lots of different Duro 50 o-rings have already arrived.]
Chen
