Quote:
Originally Posted by TrevorW
I've checked the collimation on the GSO 10" Truss RC and used a mask and everything seems in focus so I'm not sure what caused this. Captured with an Optolong L Pro filter. I'm wondering if the optics are an issue or is the filter causing this.
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Trevor,
Focus can shift even over an hour due to many factors like focuser tube mechanical movement and atmospheric conditions ( humidity, temperature etc.. ) I don’t use auto compensated focuser software , just an ZWOEAF on manual control but I do check my subs “on the fly” during an imaging session to see if focus is stable. It may save an imaging session having a periodic look ( every 20mins or so )
Also filters can change your backfocus by up to 1mm ( divide the thickness of your filter glass by a factor of 3 )
Cheers
Martin