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CA in my 80ED

Discussion in 'Telescopes and Mounts' started by PXR-5, Oct 17, 2023.

CA in my 80ED

Started by PXR-5 on Oct 17, 2023 at 9:02 AM

6 Replies 1072 Views 2 Likes

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  1. PXR-5

    PXR-5 Well-Known Member

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    PXR-5, Oct 17, 2023
    #1
    I'm pretty much a mirror guy since 1968 when I received a cardboard Newt at the age of 8.
    So I'm pretty sensitive to CA, but last night Jupiter was a mess!

    I was using a mirror diagonal and my Hyperion 24mm, I also tried a 17mm Plossl, but Jupiter looked like it was being viewed through a ST80.

    I haven't owned this Orion 80ed that long, tonight I may set up an SCT next to it to rule out atmospheric conditions.

    Any thoughts?
     
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  2. Ed D

    Ed D Well-Known Member

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    Ed D, Oct 17, 2023
    #2
    Has this scope shown CA in the past? It could be conditions causing it.

    Another possibility could be the diagonal. Try observing through it without the diagonal.

    I have eyepieces that induce CA even in the Dob. Sometimes the combination of a particular diagonal combined with certain eyepieces can induce CA.

    My suggestion is to try it on a few different nights, with and without the diagonal.

    Good luck.
     
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  3. Gabby76

    Gabby76 Well-Known Member

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    Gabby76, Oct 17, 2023
    #3
    It could also be refraction from the atmosphere.
    If this is the Orion 80mm I am thinking of they were typically very good refractors.
    Have you ever checked the focuser alignment and lens collimation before?
     
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  4. sojourneyer

    sojourneyer Well-Known Member

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    sojourneyer, Oct 18, 2023
    #4
    I concur with Gabby. There is good glass in the Orion 80 ED. I believe that the Orion ED80 80mm f/7.5 Apochromatic
    has Extra-Low Dispersion Fluorocrown FPL-53 optical glass. That is top end glass.

    No not use prism diagonals with a refractor just glass diagonals.

    I think that the problems are due to the atmospheric conditions.

    OrionED80featured.jpg
     
  5. PXR-5

    PXR-5 Well-Known Member

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    PXR-5, Oct 19, 2023
    #5
    Hey all, yes it does appear to be the atmospheric conditions.
    I set up the C5 next to it last night and I was seeing pretty much the same "CA"

    I was also observing it at about 45° above the horizon, or as I like to say; mid point between the trees and the damn streetlight. LoL
     
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  6. Gabby76

    Gabby76 Well-Known Member

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    Gabby76, Oct 19, 2023
    #6
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  7. sojourneyer

    sojourneyer Well-Known Member

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    sojourneyer, Oct 21, 2023
    #7
    or just put the scope away and listen to some AC/DC


    AustralianHighVoltage_ACDC.jpg
     
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