Check Focus
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Slew the mount to a fairly bright star and place the Bahtinov mask on the front of the telescope tube. Launch the program Bahtinov Grabber, select the area on the Artemis Capture screen where the star's Bahtinov pattern is located and monitor the result in the Bahtinov Grabber window. That window shows the same Bahtinov pattern plus a small red circle indicating where the current focus position is. Using USB_Focus, adjust the focus to move the red circle until it is centred over the Bahtinov pattern at which point a number of dotted yellow concentric circles will be displayed. Although this may be a slower method than using the FWHM feature in Artemis Capture I prefer it because it gives a simple and easily understood analogue portrayal of the focusing status and unambiguous confirmation when proper focus is achieved.
With the addition of the new USB_Focus motor to the focuser this method may possibly change. In theory, computer control now allows the focuser to be set remotely whereas the Bhatinov mask can only be attached when physically at the 'scope. So the use of the Bhatinov mask may be discontinued in favour of using the FWHM function in Artemis Capture. This changeover of procedure is currently a work-in-progress.
With the addition of the new USB_Focus motor to the focuser this method may possibly change. In theory, computer control now allows the focuser to be set remotely whereas the Bhatinov mask can only be attached when physically at the 'scope. So the use of the Bhatinov mask may be discontinued in favour of using the FWHM function in Artemis Capture. This changeover of procedure is currently a work-in-progress.