Using the Auto Focus module of SGP (v 184.108.40.206) I made some observations that need an explaination.
My scope is a Tak FSQ 106N with Robofocus motor and Seletek Armadillo2 Controller. The temperature is measured at the sope, protected against wind.
When I had a look at the logfiles I realized that SGP calculates the AF Focus Position according to 2 methods, which are called “New AF method” and “Old AF method”. SGP always uses the value calculated with the “Old AF method”. Conspiciously, the values obtained with the old method are in coarser steps than the values of the new method: my observation is, that small temperature changes often produce identical AF Focus Positions with the old method. The values of the new method are in finer steps and the change in Focus position is in the expected direction.
When plotting the AF Focus Position (as y) against temperature (as x) separately for the old and new method this is clearly visible. Doing a linear regession results in a significantly higher coefficient of determination for the new method.
So the new method affords more reliable results with my equipment, and I would like to apply these values instead of the ones of the old method. However, there is no mention of the 2 AF methods in the manual and there seems to be no setup in SGP, which method to apply.
Is this still in an experimental stage? How can we use the results of the new method? I can only imagine to manually set the focuser position to the value obtained by the new method, but that’s no practical way for me because I would have to search in the logfile every time an AF run is executed.