Auto focus reflector


#1

hi all, can anyone assist me with my auto focus routine, i run two set ups, one is my FSQ106 ed…i have no issues at all auto focusing ith that set up, nice V curve etc.
However; no matter how i try, i cannot get auto focus to run reliably on my reflector!!

The scope is an f/4.4 Orion Optics newt…focal length 880 mm, it has a CFZ of 48mm.

the focuser is a Moonlite CR1 with a hi res stepper on it, it has a step size of 0.42 microns…(i.e. 20.828 mm in 5000 steps)

i am using or have used several step sizes and # of steps to try and get a good V curve, i have been close at times but cannot repeat it consistently!!
currently i am using 12 steps and 9 positions though i have used less and more of each.

i have checked the Moonlight for slippage since it carries a QSI 583, however i cannot detect any and its position is repeatable, i have disabled smartfocus as per the advice!

any help appreciated, i want to go to bed…

Ray


#2

Ray,

Every system is unique in it’s own way. Generic advice:

  1. Find focus with a bahtinov mask. Note this position (f)
  2. Remove the mask. Move the focuser out using frame and focus, stop when “donuts” appear
  3. Move back (in) to before they appear (click the “star icon” to ensure that SGPro still detects star centroids in the center of stars. Note this position (f’).
  4. Use 9 steps of focus (data points). Step size = ((f’ - f) * 2) / 9

We might be able to lend more specific advice if you turn on focus packs and send one our way.


#3

Hi Ken thanks for the reply, i will try from step 2 since i have used a Bahtinov mask to focus but not tried that method…

if that fails I’ll send you the log…

wish me luck :slight_smile:

Ray


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