I thought I'd share where my 'eFinder' project has got. It's a small camera and lens fitted to any visual Dobsonian telescope. A Python script on a local Raspberry Pi looks after the camera, does solves, calculates Scope AltAz, and manages a tethered handpad and an optional remote full GUI on a tablet or PC.
The code feature a semi-automatic calibration feature to align the camera to the main scope. (based on wcs-xy2rd). The Pi talks to the telescope drive (if fitted) and provides alignment data and can even finish a normal 'GoTo' by nudging the scope on to the intended true sky RA & Dec.
The capture and solve takes about 2.5 seconds, and I haven't had a solve fail for months. The main scope gets pointed to within an arc minute, which for a lightweight portable Dobsonian (18") is groundbreaking. The corrected scope position is relayed back to a connected SkySafari planetarium App.
Many thanks to all who have produced and supported astrometry.net
, plus those who have helped along the way with coding and testing.