Autofocus with Askar 200 f4

Today, 07:16 AM

Hi,
Is anybody working Askar 200?

I’m using EAF motor for focusing and when I made the LocalField Robofire focus and the final focus value is HDF 3,72.
My question is if this value is not so high?
Thanks

Hi Typhoon,

I absolutely dont know your tele, first time I read about. But from image I do not see anything strange.
Remember two things:

  • HFD is not HFR, is double of this value in theory. HFR can have a big error in calculation, the error on calculation of HFD usually is 1/4 of the HFR. If you want to compare to HFR you can approximately divide by 2
  • HFD indicated by Voyager is an average of all the stars in the field

Value of HFD depends from optics and:

  • stars in the field
  • seeing
  • collimation
  • error in correct distance (backfocus) of corrector if you have one
  • exposure time
  • binning used
  • filter used

Its a value and have a relative indication of quality of focus. You must know your system how perform.
If you need an absolute way to evaluate focus you must use a tool with FWHM metric.
Voyager is not interested in this kind of metric because is not useful for manage focus system.

All the best
Leonardo

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