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Showing results for tags 'secondary adjustment'.
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Hope someone with more experience than I, which basically means anyone that has successfully collimated a Newtonian, can answer a couple of compound questions I have based on my first and only attempt at secondary collimation of my SkyWatcher Flextube 250. 1) All three of my secondary collimation screws were extremely snug before I did anything and I was only able to comfortably turn them counter-clockwise. Is this normal? Do I need to loosen all three screws first before I can properly start collimation? Should I be turning any screw beyond "snug"? 2) Before collimating, I placed a yellow sheet inside my OTA opposite my focuser tube and I placed a red sheet between my secondary and primary. The view this gave through my focuser tube was of a red circle surrounded by a partial yellow ring (the secondary mirror stalk blocking a portion of this yellow annulus). While independently turning each of the secondary collimation screws counter-clockwise I looked down the focuser tube (both with and without a sight tube installed) expecting to see some change in the shape of the red area (more or less circular) and/or the yellow area (less or more even thickness). I turned the screws no more that 2 complete revolutions. I did not perceive any appreciable difference in what I saw and I turned each screw back (clockwise) to their original tightness before working with another of the screws. Does it make sense that I didn't perceive any change? Should I have turned the screws more revolutions? Should I have loosened more than one at a time? Very confused and looking for your help. Thanks
Hello all Can I ask the question to some of you seasoned imagers if you find your flats are showing off center do I adjust the focuser, secondary or primary. I have laser collimated but the scope which is a Skywatcher 150pds has a offset. Yes I know there is a way of calculating it but I'm just a beginner in many ways. It might be nothing to do with the offset. I checked on Ccd inspector and I'm around 29% curvature but with the darker spot slightly to the right. So do I adjust the focuser secondary or the primary? Thanks for any help Gerry