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Thread: Perplexing Polarization

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    Question Perplexing Polarization



    I took my Meade 70mm AZ telescope out last night to use the full moon for playing around with my new polarizing filter. A strange kept often happening. Only half of the moon would get filtered making it look similar to but not exactly like a quarter moon. How is that happening?
    The features on the moon that stood out to me the most were the craters Plato and Proclus.
    When I got back in and was put things away I happened to look in my diagonal and it surprised me how dirty it was. I used my lens pen and a micro fiber cloth to clean it. It was my first time cleaning a diagonal. I don't think the dirty diagonal was the cause of the filtering problem.
    Donald
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    Default Re: Perplexing Polarization

    Sorry for the typo in the above. It should be Meade 60mm AZ telescope.
    Donald
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    Default Re: Perplexing Polarization

    I can't answer your question about the filter, but I do want to caution you about using a lens pen and cloth on a mirror diagonal. Google "how to clean a star diagonal" for a better approach. A mirror diagonal is a delicate thing; the mirror coating is on top of the glass, not behind it like in your bathroom mirror. It is a very thin coating and easily scratched.
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    Mary


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    Default Re: Perplexing Polarization

    By chance are you using an erecting prism instead of a standard star diagonal?
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    Default Re: Perplexing Polarization

    Quote Originally Posted by Voyageur View Post
    I can't answer your question about the filter, but I do want to caution you about using a lens pen and cloth on a mirror diagonal. Google "how to clean a star diagonal" for a better approach. A mirror diagonal is a delicate thing; the mirror coating is on top of the glass, not behind it like in your bathroom mirror. It is a very thin coating and easily scratched.
    This diagonal's mirror is protected both on the eyepiece and telescope ports by clear plastic windows. I was already aware of the delicacy of surface coated mirrors.
    Donald
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    Default Re: Perplexing Polarization

    Quote Originally Posted by smeyer8015 View Post
    By chance are you using an erecting prism instead of a standard star diagonal?
    This is the diagonal that comes with the telescope which is a Meade Infinity 60mm refractor. I'm pretty sure that it is not a prism.
    Donald
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    Default Re: Perplexing Polarization

    Quote Originally Posted by seer View Post
    This diagonal's mirror is protected both on the eyepiece and telescope ports by clear plastic windows.
    Clear plastic windows probably don't help a lot when it comes to viewing the night sky. And they may be reacting poorly with your polarizing filter. Sounds to me like you really may need a new (astronomical) diagonal.

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    Default Re: Perplexing Polarization

    Quote Originally Posted by seer View Post
    This diagonal's mirror is protected both on the eyepiece and telescope ports by clear plastic windows. I was already aware of the delicacy of surface coated mirrors.
    My apologies. I have owned several diagonals, but have never seen a star diagonal with clear plastic protectors, so when you said you "cleaned the diagonal," I wrongly assumed you used the lens pen on the mirror itself. You said it was the first time you had cleaned a diagonal, so I though you might not be familiar with these mirrors.

    I now suspect that the polarizing issue may be due to the presence of the plastic windows.
    Mary


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    Default Re: Perplexing Polarization

    I will be checking out the diagonal of my other telescope to see if it is the same way.
    Donald
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    Default Re: Perplexing Polarization

    If the polarization problem is coming from the plastic windows how is it darkening only half of the moon?
    Donald
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