The StellarMate Plus Manual
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o Centroid: a source detection based on estimating star mass around
signal peaks.
o Gradient: a single source detection based on the Sobel filter. Initial or
full-field analysis will use SEP instead of this method.
o Threshold: a single source detection based on pixel values. Initial or
full-field analysis will use SEP instead of this method.
o Bahtinov: This is useful for users who do not have a motorized focuser
and prefer to focus manually with the aid of a Bahtinov Mask. After
capturing an image in the focus module with the Bahtinov mask
algorithm selected, Ekos would analyze the images and stars within it.
If Ekos recognizes the Bahtinov star pattern, it will draw lines over the
star pattern in circles on the center and on an offset to indicate the
focus.
· Threshold: Threshold percentage value is used for star detection using
the Threshold detection algorithm. Increase to restrict the centroid to bright
cores. Decrease to enclose fuzzy stars.
· Effect: Apply filter to image after capture to enhance it for preview
purposes. It is highly advisable to turn off any effects during the focusing
process as it may interfere with HFR calculations.
· 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 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 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
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 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 dsolution radius.
Caution
Setting the value too low might result in repetitive loop and would most
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