<I have installed a new Newtonian OTA and since doing so SGP keeps reporting that Smart Focus Failed, yet I have disabled Smartfocus as I have a central Obstruction.
I cannot find a way to stop the smartfocus from attempting to do so, yet if I manually tell the sequence to focus, it does that without fail>
The new AF routine reports just that, if it cant find a good focus after trying several times, even though the smart focus is disabled. Mine does the same. Not sure how that checkbox applies to the new focus routine.
Anyway, after looking at your log using the AF Logviewer, it is clear that there were no range shifts, instead the AF failed after 3 attemps using the same range, because none of the curves passed the default minimum quality Q of 90%:
The curves dont look that bad, but the “ear” in the beginning of each curve indicate backlash, and that might be what lowers the Q value. I suggest you enable backlash, and put it at 200-300 steps. See what that does. You might want to increase you step size ever slightly, but test the backlash first.
My stars are coming our beautifully pin sharp at 1200mm fl and when I focus out of the sequence the results are excellent.
Surely if you tell it not to use smart focus, then it shouldn’t report that smartfocus has failed.
This was a quick screen grab from the other night, I still have a little tilt to fix, but there doesn’t look like there is much wrong with a single 1200s x Ha: -
The new routine is trying to maintain a high quality Q factor, so if it drops below 90% (default value) it will try to repeat. It is unfortunate that the term “smart focus” is used for the two.
You can also lower the minimum Q value for accepting a AF run, by using the “quadratic_fit_min_quality” parameter in the “Variables” field in “Sequencer” window. If you put it to “quadratic_fit_min_quality=0.8”, then any AF run with Q >= 80% will be accepted. See here:
Your step size is fine. Just do what Mikael has suggested: please INCREASE your focuser backlash value (by about 50 - 60 steps), and don’t touch the variable “quadratic_fit_min_quality”.
Thanks Mikael & Bernd, you may well be right about the backlash as I normally have it calculated for my other OTA’s but had forgotten to on the Newt, so will try at 60. I normally I trap a piece of paper between the draw tube of the focuser and the housing and keep manually moving it out until it drops and that then is my backlash calculation.
There is no need for adjusting backlash exactly to a measured value. If you get 60 then put 100 and it will focus the same and that way you make sure that you are well covered for backlash.
From SGP Help: Compensation step size:The number of steps to move to remove the backlash. This number does not need to be precise. If anything it needs to be larger than the total backlash in the focuser, so overshoot
