Gerry Casa Christiana Posted October 28, 2017 Share Posted October 28, 2017 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 Link to comment Share on other sites More sharing options...
PhotoGav Posted October 28, 2017 Share Posted October 28, 2017 Don’t change anything just for the flats. So long as the scope is collimated, just accept whatever the flats look like, so long as they are exposed properly. Most of my scopes show the light cone to be off centre in the flats. It’s not a problem and doesn’t need to be fixed! Link to comment Share on other sites More sharing options...
Gerry Casa Christiana Posted October 28, 2017 Author Share Posted October 28, 2017 I think there is a problem because it's not just the flats but also the pictures. I seem to have elongated stars in the corners. It's a real pain! Not sure what to do. Thanks Gerry Link to comment Share on other sites More sharing options...
PhotoGav Posted October 28, 2017 Share Posted October 28, 2017 6 minutes ago, Gerry Casa Christiana said: I think there is a problem because it's not just the flats but also the pictures. I seem to have elongated stars in the corners. Ah, yes that is definitely an issue. It sounds like coma to me - do you use a coma corrector? I am no expert with the 150pds, so can't much help there, but I'm sure that a knowledgable sort will be along very soon to help. Good luck! Link to comment Share on other sites More sharing options...
Gerry Casa Christiana Posted October 28, 2017 Author Share Posted October 28, 2017 Yes I use a corrector. Wish it was that easy Thanks for the help Gerry Link to comment Share on other sites More sharing options...
alacant Posted October 28, 2017 Share Posted October 28, 2017 3 hours ago, Gerry Casa Christiana said: elongated stars in the corners Hi. Move the camera a mm or so away from the coma corrector. HTH. Link to comment Share on other sites More sharing options...
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