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  1. #1
    therealroland's Avatar
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    Default Placement of Barlow / Eyepiece on Diagonal



    Hey,

    I recently received my 2" 2x Barlow, and was wondering where in the 'optical train' to place it.

    option one:
    focuser -> barlow -> diagonal -> eyepiece

    option two:
    focuser -> diagonal - barlow - eyepiece

    Option two so far works - focusing seems not to be a problem, as long as I place the barlow 'at the end' of its tube - see photo # 1 rps20150720_115350_501.jpg

    Now, i can of course completely insert the barlow, so that it sits completely deep into the focuser - see photo # 2 rps20150720_115451_327.jpg

    But that seems to shift the focus point (which i think makes sense, since the barlow lens is now closer to the diagonal, etc.)

    What's the general preferred method?

    And what about option one? Do i need any extender tubes to get things into focus again?
    Nikon Monarch 8x42 / 12x42 binos - Canon 7D - Sigma 150-500mm f/5-6.3 AF APO DG OS HSM Telephoto Zoom Lens - 1.4x extender - Celestron CG-5 Goto mount - Explore Scientific 80 mm Essential ED Triplet - Telrad finder - Baader Hyperion Zoom mkIII (8 - 24mm) - Baader Planetarium Moon & Skyglow filter - Manfrotto 055x tripod, 322RC2 ball head with quick release plate (ballhead bit too lightweight for ED80 + dovetail plate!)


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  2. #2
    Dragonsfire's Avatar
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    Default Re: Placement of Barlow / Eyepiece on Diagonal

    Option two is what I use (just don't use diagonal)
    Neil
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    XT8i, AR102
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    ES24, 18mm 2", 11mm
    Agena 38mm 70SWA 2", 6mm, 25mm Ortho Volcono top.
    TeleVue 3X Barlow Long, TELRAD, Oly E-PM2, ASI120MC,
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  3. #3
    therealroland's Avatar
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    Default Re: Placement of Barlow / Eyepiece on Diagonal

    yeah, already found out that i should not use the diagonal when using my extension tube and t-ring/t-ring adapter. That's causing focus issues as well.

    so, Neil, how do you look at things when they are way up in the sky, when not using the diagonal?
    Nikon Monarch 8x42 / 12x42 binos - Canon 7D - Sigma 150-500mm f/5-6.3 AF APO DG OS HSM Telephoto Zoom Lens - 1.4x extender - Celestron CG-5 Goto mount - Explore Scientific 80 mm Essential ED Triplet - Telrad finder - Baader Hyperion Zoom mkIII (8 - 24mm) - Baader Planetarium Moon & Skyglow filter - Manfrotto 055x tripod, 322RC2 ball head with quick release plate (ballhead bit too lightweight for ED80 + dovetail plate!)


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  4. #4
    Dragonsfire's Avatar
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    Default Re: Placement of Barlow / Eyepiece on Diagonal

    Display from the camera when im doing prime focus but that's just planets/moon. I don't need a diagonal for general vueing
    Besides the amplification, the Barlow (Long) deals with the backfocus problems, shorty does not work for Dobs from my experience.
    Neil
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    XT8i, AR102
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    ES24, 18mm 2", 11mm
    Agena 38mm 70SWA 2", 6mm, 25mm Ortho Volcono top.
    TeleVue 3X Barlow Long, TELRAD, Oly E-PM2, ASI120MC,
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  5. #5
    therealroland's Avatar
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    Default Re: Placement of Barlow / Eyepiece on Diagonal

    Yeah, will slowly start experimenting with using my camera and this scope; see how it works with the barlow, t-ring/adapter, etc.

    Fun stuff!
    Nikon Monarch 8x42 / 12x42 binos - Canon 7D - Sigma 150-500mm f/5-6.3 AF APO DG OS HSM Telephoto Zoom Lens - 1.4x extender - Celestron CG-5 Goto mount - Explore Scientific 80 mm Essential ED Triplet - Telrad finder - Baader Hyperion Zoom mkIII (8 - 24mm) - Baader Planetarium Moon & Skyglow filter - Manfrotto 055x tripod, 322RC2 ball head with quick release plate (ballhead bit too lightweight for ED80 + dovetail plate!)


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