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Thread: Eyepieces

  1. #1
    conorfitzsimons's Avatar
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    Default Eyepieces



    Hello all,

    I got my Skywatcher Explorer 130P Synscan for Christmas. Really loving it!

    With the scope, the pieces I got are:



    So I noticed the 10mm is shorter than the 25mm...

    Then I was looking www.opticstar.com and I seen this set.

    Sky-Watcher 1.25" Eyepiece & Filter Set.

    In the picture the 2mm looks alot longer than the 20mm.

    Would the 2mm give me stronger magnification that what I already have, even though the lens, is physically longer.

    Sorry that this thread it a bit all over the place, Let me know on any points you aren't clear about.

    Clear Skies,

    conorfitzsimons

  2. #2
    Zeiss's Avatar
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    Default

    yes, the shorter the focal length will give you higher magnification. I do not recommend that set though. That set will add nothing new to your collection aside from the case and possibly the flashlight. Since you already have a 25 and 10, with barlow it would be a 12.5 and 5. And the 2mm will be too much for your scope.
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  3. #3
    MitchAlsup's Avatar
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    Default

    The 5mm and the 2mm from the link are special kinds of eyepieces. Special in that the actual eyepiece part of the EP is rather conventional, but before the light gets to that part it passes through a negative powered lens (sometimes in this configuration called a Smythe lens).The combination creates the very short 'effective' focal length.

    {Asside: your 25mm becomes a 12.5mm EP when placed in the draw tube of the 2X Barlow for exactly the same <first order> optical reasons.}

    The 2mm is PROBABLY a lot more magnification than your scope can use. The 5mm is on the edge of being more magnification tahn you can effectively use (at least most of the time.)

    Also note: You have a 12.5mm EP (made from the 25mm in the 2X Barlow) and a 5mm EP (made from the 10mm in the 2X Barlow) already.

    The filters are the typical collored filters that are seldom used except for certain kinds of planetary viewing.

  4. #4
    Joe Lalumia's Avatar
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    Default

    You cannot tell anything by "size or length". Simply divide the focal length of the scope by the number (mm) written on the eyepiece-- this gives you the magnification.

    Example: My LX90 is 1200mm focal length

    A 10mm eyepiece gives 120 power.

    A 20mm eyepiece gives 60 power.

    Remember that magnification is the least important quality of a telescope -- quality optics and aperture are more important.

    Clear skies to you.
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    Default

    If I had the same equipment you have I honestly would be looking for a 30 mm eyepiece... 10 25 and 30 when used by them selves BUT 5 12.5 and 15 when used with the barlow...in realty you would have 5 10 12.5 15 25 and 30 mm eyepieces ...

    Heck I might even consider buying a 40 mm eyepiece along with the 30

    that would give you the equivalent of 5 -10- 12.5 -15- 20 -25 -30 and 40 mm eyepieces and I woudl also bet that you find yourself using the 25 30 and 40 by themselves more then you would the other combinations combined...

    Bob G.
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