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Bahtinov diffraction pattern not right

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  • 22 April 2026 at 9:28 am #637238
    Alan Snook
    Participant

    Hi Folks,
    Last night I put a Bahtinov mask on my Altair Astro 130EDT refractor. The diffraction pattern I am seeing at point of focus is not the expected cross with an intercept. Any suggestions on what the reason may be please?

    • This topic was modified 3 hours, 33 minutes ago by Alan Snook.
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    1. Bahtinov-star_00001.png

    22 April 2026 at 12:23 pm #637242
    Dr Paul Leyland
    Participant

    Are you sure that the scope is in focus?

    The vertical line is usually outside the cross when it is severely out of focus. Otherwise, I have no idea at present.

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