Charding, I would love to be able to do this myself. I have an Ioptron CEM25ec with a WO GT71 with a .8 reducer so I am at about 340FL . With that combo the tracking is good enough for me to get very decent 5 minute subs. But I need to guide to dither. And there in is by far my biggest problem. In spite of every effort and countless adjustments even including the recent FW update for my ASI 120mm mini my guiding is a total mess. I'm reaching the point where I am seriously getting ready to give up on the ASIair Pro. I'm starting to consider going to PHD2 and whatever else I need to start enjoying my equipment, and getting some decent subs to stack, instead of wasting the few clear nights we have struggling with the guiding. Obviously your suggestion has a lot of merit for me. If I could dither without guiding I at least could start using my equipment productively while ZWO hopefully finally completely resolves whatever the problem is with the ASIair Pro guiding software.