View Single Post
  #4  
Old 06-06-2018, 11:03 AM
OuterObsession's Avatar
OuterObsession (Jameson)
Registered User

OuterObsession is offline
 
Join Date: May 2018
Location: NORMAN PARK
Posts: 37
I don't quite understand how to determine which wavelength I should be using for the calculations. Also is depth of focus the same thing as CFZ? When I use IanLs calc I get a CFZ of 178.2 microns, but when I use your calculation I get 45.9microns (theoretical) 117.9 (seeing) which would lead me to believe that the area for "good focus" is actually a lot smaller than I think.

This is how I set up the focuser on my ed100 currently. As you can see there's no gearing atm. Based on IanLs formulas I get 2.8512 steps in the 'perfect' focus area.

Because of that I'm replacing the nema17 with a 5:1 reduction gearbox, but unfortunately the gearbox adds about <=1° of backlash. So that would be around +/- 3 steps in the CFZ.

I do not use a flattener atm but with my current setup I haven't had issues with the focuser running close to the end of the drawtube. I usually just manually bring the focus in roughly then start the APT autofocus routine so I'm not waiting there forever.

How do you focus if your imaging target doesn't have any focus stars in frame? Goto commands with platesolve?? I haven't done a lot of long imaging sessions in APT yet so I'm still trying to work all this stuff out.
Attached Thumbnails
Click for full-size image (a7638f96-b461-415f-866d-e9279862cf1c.jpg)
191.3 KB25 views
Reply With Quote