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Thread: Eyepiece issue?

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    pe51c's Avatar
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    Default Eyepiece issue?



    I bought new Celestron Omni 32mm (plossl) eyepiece for my Astromaster 130 telescope. Secondary mirror is quite visible as a fuzzy dark blob when looking during day.I never noticed this with original eyepiece (20mm ,some kind of 3 lens design). I didn't have chance to test new one on stars yet because of clouds. Looking down the street at night is fine,secondary mirror shadow is not noticable. Overall views are much nicer with Omni 32mm.

    Is this something to be expected ?
    Tnx
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    Default

    With most scopes with a secondary mirror you will see a shadow of the secondary mirror in the daytime. At night it is not normaly vissable. (not enough light to make a shadow) for daytime viewing scopes without a secondary mirror or other obstruction are best. (refractor). Don T.

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    Default

    Yes, I had the same experience and almost freaked out! I think it has to do with the relative size of your pupil and the telescope exit pupil. Since your pupil will become smaller when viewing bright objects as well, you may see the same effect when viewing a full moon. It should not present any serious problem otherwise, although I wonder if it may result in lower resolution than a refractor. Perhaps someone here will be able to tell us more.

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    Default

    Exit pupil and eye relief come into play so you may have to adjust your head position on some occasions.... Should not be a problem at all when using the eyepiece under the stars...(like at night)

    In practical terms you are not loosing any resolution ... with the eyepiece....


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    It begins to happen when you approach the theoretical minimum magnification of the scope. The exit pupil gets too big. I had to exchange a 35mm for a 30mm when the 35 overpowered my 5" dob.
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