Step size for new stepup


I have just spent too much money and bought an AT65EDQ 65mm f/6.5 ED quadruplet astrograph with the moonlite focuser with the stepper motor. Does anyone have any experience with this combo and found good setting for the step size and other setting in the auto focus settings


You would have to work out the CFZ for your scope which is around 114mm I believe, the moonlite is quite a fine resolution if I recall correctly… About 4 microns per step so a rough rough guess!!
Step size 30?? As a first try.



I’ve used this combination in the past. Here are the settings I would suggest, but some experimentation will be necessary:

If you don’t want to use focus/filter offsets and autofocus with the actual filter, uncheck “Auto Focus with filter: LUM”.

Don’t worry so much about all the numbers and calculations. What you want is a nice “V” focus curve with the outer two points of the V being about 4x the HFR of the bottom point. So for example if the system is in focus and it gives you an HFR of 1.0, then the outer two points of the V curve should be around 4.0


thanks for the suggestions !!!


I am using your exact set up.
I have a step size of 10 and using 7 data points. (4.06 mics per step according to Ron)
I am also using FWHM as I have Pinpoint.

I get very good results but I may increase my step size to see if I can get the 4X that is mentioned. First I ran into it, but that is probably from lack of reading on my part.
Maybe the higher step size will cause it to finish quicker ?



Peter, rather than increase your step size, I would suggest increasing the number of data points to 9 if you want to get more intra and outer focus. The 4x figure is just a guide. Anywhere from 3-4x is optimal in my experience.


Thanks, I will try that, maybe tonight if these clouds disperse :slight_smile: