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What sort of scope is it? What f #, that influences secondaey offset. Looking at your photo, its hard to tell if the photo is centred properly. If i assume it is, then rhe secondary is tilted, you can tell this because you can see the secondary vane mount blocks on the upper left of the photo. Do you have a Cheshire tube to check secondary placement? Or even a focuser plug with a centre hole can be used for this. Suggest you read Astrobaby's goid article on Collimation, which should be in the Artickes section of this forum.
Good luck.
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