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Centering secondary mirror

27 May, 2019 19:41
Hi !
I need to collimate my newton (200mm f/4) and I saw somewhere that the secondary mirror need to be a little bit decentered for telescope with big aperture (like f/4). Is it true ? If yes, why ? And is it necessary even with a barlow 3x (f/12) ?

Clear skies,
27 May, 2019 20:24
You can check a thread I started a couple of years ago on Cloudynights:

it has been very useful to me.


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