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    Default How much more from a 2" EP



    Thinking of moving up to my next telescope I'm wondering how much sight or FOV am I getting with a 2" EP? Is it worth weighing on a choice for a new scope? And exactly am I getting with a 2" over the 1.25"?
    Meade DS-2114S autostar/GOTO 6.4mm plossl, 9mm, 25mm, 2X barlow
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    Quote Originally Posted by Savage750 View Post
    Thinking of moving up to my next telescope I'm wondering how much sight or FOV am I getting with a 2" EP? Is it worth weighing on a choice for a new scope? And exactly am I getting with a 2" over the 1.25"?
    The advantages of a 2" light train are not necessarily great in some ways. Its going to come down to the types of EP's that you may plan to use and the focal length of your scope.

    In general using standard Plossl type EPs there is absolutely no advantage in 2" until you go to EPs of 32mm or longer focal length. Incidentally if you have a scope of very short focal ratio, say f/4 or less, then standard plossls aren't going to work particularly well at all in any case.

    The actual switch to 2" does have an advantage with EPs with wider than standard Plossl AFOV

    Examples are:

    If you want to use 100░ AFOV EPs then 17mm or longer will need to be 2" for maximum advantage, at 82░AFOV it is 20mm and at 68░AFOV 27mm will be the magic number.

    You may also note that a 100░ AFOV EP is probably going to cost you more than your next scope

    From my personal perspective, however, there is a very strong case for the reason that I only use 2" focusers, diagonals, and barlows (ie 2" light trains) and that is my preferred EPs are very physically large and heavy. In a 2" system large and heavy EPs are much better mechanically supported than in a 1.25" system despite there being no actually gain over 1.25" in actual view in the shorter EP lengths.

    Similarly from an AP perspective a 2" focuser offers much better mechanical support for a camera than does a 1.25"

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    I should have added here that a lot of scopes these days are fitted with 2" focusers. These also come with an adaptor to 1.25" so you can certainly use your 1.25" EPs in a 2" system. I think that it is worth having a 2" focuser available even if you don't use it to advantage its always there for the future

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    ... what he said ... lol ...

    ... thanks for those numbers Vin ... I'm taking notes ...

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