Auto Focus

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Description:  Auto focus is an excellent step towards automated imaging.  If setup correctly you can complete an entire imaging run with little to no interaction with your equipment once the "Run Sequence" button is clicked.  Auto focus assumes that you're already well focused with a Bahtinov Mask or some other focusing aide.  The intent of auto focus is not to take you from completely out of focus to in focus, but to keep you in focus throughout the entire night.  For more information on how auto focus works and how to best tune your setup to get the most out of auto focus please see Understanding Auto Focus.


Auto focus can be invoked by using the Focus Control Panel or the Focus Module:


Above: Focus Control Panel


Above: Focus Control Module


Setup


The majority of the auto focus options can be found in the Profile Manager under the Focus Tab, these options are also available at a sequence level in the Control Panel.  The illustrations below are from the Control Panel.  Clicking the "Set" button next to the "Use auto focus" option will bring up the Focus Options Window.


The text below will describe what each fields represents, but will probably not leave you with a great feeling in terms of how to tune these setting for you rig.  For that we have devised this section which, we hope, will help get you up and running with AF pretty quickly.


To use Auto Focus you will need to have a camera and a focuser which can return its absolute position.



Options:


Note:  While not on this dialog, the auto focus routine can run using fast download speeds (assuming your camera supports it).  This option can be found on the Camera tab of the control panel.  There is no harm in trying it... just a word of caution, that for some cameras, this might introduce enough noise or other unfortunate artifacts that the AF metrics are less than optimal.


Manually Running:


You can manually invoke the Auto Focus routine either through the Focus Module or from the Focus Control Panel by clicking the "Run" button.  This will bring up a window that resembles the window below:




If you are unhappy with the auto focus results (ie you don't get a good V curve or the V seems shifted dramatically to one side) you can invoke Auto Focus again by clicking "Run Again".  This will center the Auto Focus run around the point that was last determined to have the best focus.


The Validation Frame


After auto focus is complete and SGPro has determined the new focus position, it will move the focuser here and take a validation frame.  Because of the way in which SGPro achieves auto focus, it has a pretty good idea what your ending HFR should be if you truly arrived the focus position.  If the validation frame's HFR is not within 15% of the low HFR, a temporary warning dialog will appear and let you know (if you purchased the notification add-on, a notification will also be sent).  If this happens often, it might be due to backlash issues in the focus motor, underpowered focuser motor (heavy imaging chain fighting gravity near meridian) or some sort of binding.


If you cancel the auto focus run after it has completed the focuser will be returned to the last focus position.  For example:


However if "Run Again" has been used this will reset the start position.  For example: