Add manual input of focus steps to AF final value to correct for corner stars

I am not sure if this has been brought up before but perhaps it is a potential helpful add to the AF options. I am proposing that we allow a user selected offset or padding value of focuser steps to be added or subtracted to each filter to help correct for corner stars. This is not to be confused with using filter offsets in the traditional sense here. I am testing a new reducer that is extremely critical to focus and even if I use an .99 to .9 (outer to inner crop ratio donut) it still leaves the AF at a point where the stars are visibly elongated on all edges. There is not a traditional backspacing number per say for this scope, so once you are at focus you are spaced correctly. So I can not add a spacer to correct for this. Instead, if we added a factor of, in this particular case 100-200 steps, to the final focus position that the AF routine comes up with, then I can better average the stars across the entire field. This is going to be more applicable as more of everyone here gets their APS-c cameras and more users are using the FF as well. As far as I can tell the AF routine is measuring center of mass and not elongated shape/eccentricity so it misses the opportunity to average the stars to a better result where the inner stars are potentially slightly bloated but still round and the outer stars are substantially more round.

This could be a input in the AF prefs or potentially a sequence plugin or AF sequence added field.

February 22, 2021

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