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Thread: Mirrors: Skywatcher 20" vs Hubble Optics 20"

  1. #1
    Member davidem27's Avatar
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    Mirrors: Skywatcher 20" vs Hubble Optics 20"

    Good morning y'all!

    I decided to make the big step: upgrade my 16 to a 20 inches, self made.

    I'm trying to set a stable-but-portable scope and I was looking for a lightweight mirror in worldwide markets.

    My eyes dropped onto these two mirrors: weights are really lighter than other Pyrex standard mirrors.


    The next questions are

    - What is their real optical quality?
    - How much the coating is good in these two type of glasses?
    - Is it durable through the years?
    - Has the parabolized surface made without rugosity, considering they are industrial made mirrors?

    I think these questions could be only answered by owners that had (hardly) tested and measured these optics alongside with precise benchmarks, and also have posted mirrors for many years.

    I would be glad to discuss with you about mentioned issues.


    Davide
    Davide Pistritto - Visual Sky Assist - plan your observation
    Dobson 16" f/4.5 - TeleVue Ethos and Nagler with Paracorr - 1000 Oaks filters on filterslide

    Beware for your CDDs! eheh...

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    The Skywatcher quality control on these is "1/4 wave". See my last blog post for some pretty fine detail in M81 that I caught with mine on a cold but very stable night. I've only looked through an 18" Hubble at low-medium power; not much of a test. Good luck with your project.
    Last edited by Ivan Maly; January 12th, 2018 at 02:10 AM.

  3. #3
    Member davidem27's Avatar
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    Thanks for fast replying Ivan!
    Your HII observations about M81 are very interesting.

    What is your favourite magnification, using Stargate dobson?
    Do you observe at 250-300x?
    How does the mirror works at these powers?
    Davide Pistritto - Visual Sky Assist - plan your observation
    Dobson 16" f/4.5 - TeleVue Ethos and Nagler with Paracorr - 1000 Oaks filters on filterslide

    Beware for your CDDs! eheh...

  4. #4
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    I have just got the scope for Christmas and made one short dark sky run to use the rare winter clearing. 250x looked perfectly fine. I plan to use higher magnifications often and report on it in the coming months.

  5. #5
    Member davidem27's Avatar
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    My ears are fully opened

    Thanks again Ivan.
    Davide Pistritto - Visual Sky Assist - plan your observation
    Dobson 16" f/4.5 - TeleVue Ethos and Nagler with Paracorr - 1000 Oaks filters on filterslide

    Beware for your CDDs! eheh...

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