Thanks for your response John.
I will wait for the new KStars release as I haven't quite got around to building it myself.
Regarding the traffic light system idea you described, correct me if I am wrong but to me it sounds more of a "how close you are to the ideal" kind of an indicator.
I suppose it would use CFZ as its main reference and would light green when the delta between the smallest and the largest solutions (out of 4 corners & center) is within CFZ.
I was rather talking about the measure of trustworthiness, if you will, of the tool's output, as it relates to current atmospheric conditions.
I do not really see an obvious way to quantify that other than having the user run the autofocus routine several times without any adjustments and then fitting the results into some [normal] distribution.
Then you would be able to show, right next to your output of Delta (ticks), how it compares to the calculated standard deviation.
If my Delta readings turn out between -20 and 10, but the standard deviation is 30 (just an example, you could use a derived metric, such as 2 sigma, or whatever else), I would know not to bother any further.
Another approach could be to make use of PHD2's guiding assistant output (or some similar routine) where it estimates the high-frequency atmospheric vibrations, but I suppose it could end up quite sophisticated as essentially you would need to translate those readings (which relate to the camera sensor plane) into what would need to relate to distance of focuser travel in the direction perpendicular to the camera sensor plane.
That, in turn, would probably need to rely on how exactly a star image changes with focuser move, e.t.c..
Now, regarding where (corners / adjustment screws) the adjustments need to be made, I think you have already basically nailed it in your video @
13:55
where you rotated the 3D graph and said "I'm sort of looking at this towards the telescope".
I think all the user needs to know is how the coordinate grid relates to their camera sensor. From the tool's perspective it means showing
- Where the telescope is (which side of the sensor plane on the graphic). Maybe just show an arrow towards the telescope where the "Axis of Telescope" label is?
- Where the top of the camera is, which is already done by the TL/TR/BL/BR labels