The StellarMate Plus Manual
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· Kernel size: This is the gaussian blur kernel size. Used for blurring the image
before for instance the Bahtinov edge detection.
· Sigma: This is the gaussian blur sigma value. Used for blurring the image
before for instance the Bahtinov edge detection.
· Algorithm: Select the autofocus process algorithm:
o Iterative: Moves focuser by discreet steps initially decided by the step
size. Once a curve slope is calculated, further step sizes are calculated
to reach an optimal solution. The algorithm stops when the measured
HFR is within percentage tolerance of the minimum HFR recorded in the
procedure.
o Polynomial: Starts with the iterative method. Upon crossing to the other
side of the V-Curve, polynomial fitting coefficients along with possible
minimum solution are calculated. This algorithm can be faster than a
purely iterative approach given a good data set.
o Linear: Samples focus inward in a regular fashion, using 2 passes. The
algorithm can be slow, but it is more resilient to backlash. Start with the
focuser positioned near good focus. Set Initial Step Size and Max Travel
for the desired sampling interval and range around start focus position.
Tolerance should be around 5%.
· Tolerance: The tolerance percentage values decides when the autofocus
process stops in the Iterative algorithm. During the autofocus process, HFR
values are recorded, and once the focuser is close to an optimal position, it
starts measuring HFRs against the minimum recorded HFR in the sessions and
stops whenever a measured HFR value is within % difference of the minimum
recorded HFR. Decrease value to narrow optimal focus point solution radius.
Increase to expand solution radius.
WARNING
Setting the value too low might result in a repetitive loop and would most
likely result in a failed autofocus process.
· Average over: Sets the number of frames to capture in order to average the
HFR value at the current focuser position.
· Num. of rows: The number of rows set in this field will be combined in the
Bahtinov max average calculation. Changing this value might help to match
the Bahtinov lines on the star pattern more accurately.
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