ONAG and SGP

I have an IFI ONAG SC on order and have been contemplating how to integrate it into my system which consists (partially) of an AT8RC, SBIG ST-8300M/FW8-8300 FW, Lodestar, and Moonlight Stepper focuser. My observatory is fixed (8’ dome) and none of my operation is done remotely nor do I contemplate moving to unmanned remote operation in the near future.

SGP is my program of choice for sequencing and PHD2 for guiding. I have not been using SGP for auto focusing, just manual focus using a mask. When the ONAG arrives I thought I would play with the Optec/IFI FocusLock software to see if real time focusing was “real” or not. But, there is a small problem.

My Astrodon LRGB and Bader NB filters are not parfocal (2mm vs 3mm), meaning that I must be able to communicate the offsets to the focuser. The SBIG FW, being non-ASCOM, cannot talk to FocusLock. So, what I was thinking was to characterize the filter offsets at a given temperature, store them in the SGP Filter Setup and let both SGP and FocusLock talk to the Moonlight focuser (I tested this with SGP and APT, seems to work). When the SGP sequencer commands a filter change, the focus point will move to the preset value for that filter and FocusLock will trim the focus depending on the information furnished by the ONAG.

Any comments and/or suggestions would be appreciated, particularly if you have ONAG experience. Now, if we could just get some clear skies in Central Texas …

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