FocusMax Settings

I now have my V-curves in FocusMax and want to enable the focus convergence. To do that I need to work out Critical Focus Zone (CFZ) and translate that into focuser steps.

CFZ for a scope can be worked out with this fomula:

CFZ(in Microns) = 2.2 x (Scope_Focal_Ratio²)

My RC8 having a focal ratio of 8 gives me a CFZ of 140.8 microns.

That sounds tiny in everyday speak, good thing that I have an awsome high resolution stepper motor focuser.

According to Moonlite focuser manual, 1" travel of the drawtube requires 6135 full steps, wow! that's a lot of tiny steps, 1 micron = 4 steps to be exact.
This leaves me with CFZ = 35.2 steps
So, for the step width in focus convergence setting, I want to set it with  approximately 1/10th to 1/4th of the CFZ step value say 5 steps.

Now to set the various Half Flux Diameter (HFD) values, I'll need to look at my V-curve log.

 The smallest value on the linear parts of the v-curve before it reaches focus seems to be about 6. Increasing this value by 1/4 gives me 7.5(8) to set as Near Focus HFD. This value can be increased by a 1/3 to set as Focus Start HFD, which is 10. The smallest value on the plot is 4.2, increase this value by 1/2 to set as Focus Routine Max HFD, which is 6.3.

Next thing to do is fine tune the V-curve. I'll leave that one for another night....so much too learn...