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  1. #1
    AK's Avatar
    AK Guest

    Default Meade Value Pack Plossl eyepieces



    I bought this set of 6 mm Plossl, 4 mm Plossl, and Barlow 2x lens eye pieces
    for my Celestron Nexstar reflector and have been very disappointed. Is the
    magnification just too much for this small a scope? The field of view is so
    small that finding the object I want to view is very difficult, and the
    image seems very blurred - really I am no better off than with the 25 mm and
    10 mm that came with the original scope. Was I mistaken to assume that the
    Meade lenses could be used with a Celestron scope? Or is this set simply a
    cheap and not very good set of lenses?

    Was out viewing, among other things, Saturn to night - spectacular even with
    my small scope due to the cold and windy weather which kept the sky over
    Washington very clear for once. But, as I say, my best viewing was with the
    original lenses, and the 6 mm and 4 mm Plossl's were really no better than
    the original lenses.

    Alan




  2. #2
    JAS's Avatar
    JAS Guest

    Default Meade Value Pack Plossl eyepieces

    Nothing wrong with the eyepieces. Also, there is no problem with
    incompatibility between brands -- Meade, Orion, Celestron, TeleVue,
    University Optics, etc., -- any eyepiece can be used with any scope.

    You are more than likely running into two phenomena:
    1. Sky conditions.
    2. Maximum magnification.

    Sky conditions
    The greatest limit to what you can see through your scope is atmospheric
    conditions -- what is referred to as "seeing." What looks to your naked eye
    like a clear, sparkling night may be not so good through the scope.
    Remember -- you are viewing the object through 30-50 miles of air and that
    air contains industrial pollution, moisture from natural sources, ice
    crystals, and the like -- plus -- the atmosphere is changing temperature as
    the night gets cooler while the earth remains fairly warm, thereby causing
    currents of warm air to rise, further disturbing the atmosphere through
    which you are looking.

    Check out the atmosphere with your naked eye. Are the stars twinkling?
    Bad -- that means air currents are rising from the earth and the turbulence
    of those air currents is causing the stars to twinkle. Is there a "ring" or
    a bright area around the moon? Not good -- this means there is moisture in
    the air that will not only interfere with your seeing but that will also
    condense on your optics. In fact, unless you live in a dry climate, most
    nights you will experience so-so seeing.

    Maximum magnification
    What is the aperture of your scope in inches? Aperture in inches multiplied
    by 50 or 60 equals the maximum magnification you can expect from your scope.
    Focal length of the scope divided by focal length of the eyepiece equals
    magnification. Here is what this means on my scope, an Orion XT-8, 8-inch
    reflector.
    Aperture: 8 inches
    Focal length: 1200 mm
    Maximum magnification for my scope: 8 inches x 50 or 60 = 400X to 480X;
    thus, the most magnification I can expect from my scope is 400X to 480X
    Eyepiece magnification:
    -- 32mm eyepiece: 1200 mm scope focal length divided by 32mm eyepiece =
    38X, or, 38 power magnification
    -- 32mm eyepiece with a 2X Barlow = 76X
    -- 4mm eyepiece: 1200mm scope FL divided by 4mm eyepiece = 300X
    -- etc, etc, etc

    Now, sit down with your scope. Calculate the max magnification using your
    aperture then calculate the magnification of your eyepieces.

    The fact is, you are not likely to be able to approach your scope's maximum
    magnification because seeing conditions will limit the clarity of what you
    see long before you get to max mag.

    On my 8-inch Dobsonian, I find that 170X is a good magnification -- when I
    get to 250X, things don't look any better because atmospheric conditions
    begin to degrade the image. 170X is a good magnification for me -- I can
    see shadow transits of Jupiter and the Cassini Division in Saturn's rings.
    170X showed the Martian polar cap in clear detail along with surface
    features of Mars.

    Hope this helps.

    --
    ----
    JAS


    "AK" <a.kolnik@delete-this-part-that-stops-spam.verizon.net> wrote in
    message news:l2bEb.17110$G9.7317@nwrddc01.gnilink.net...
    pieces
    so
    and
    the
    with
    the



  3. #3
    AK's Avatar
    AK Guest

    Default Meade Value Pack Plossl eyepieces

    Thanks for your informative and careful reply!

    Actually, viewing (at least for Washington) was spectacular sky very, very
    clear for once.

    Alan

    "JAS" <maxleonard@hotmail.com> wrote in message
    news:brrvmk01d9n@enews3.newsguy.com...
    eye
    as
    turbulence
    or
    in
    multiplied
    scope.
    maximum
    the
    is
    a
    than



  4. #4
    AK's Avatar
    AK Guest

    Default Meade Value Pack Plossl eyepieces

    I had a chance to do the calculations tonight (cloudy skies!).

    My scope is the 114GT, and it has a 4.5" mirror and 1000mm FL.

    So, using your rule of thumb of, say, 50 ax aperture= magnification, my
    maximum magnification is in the ballpark of 225.

    Now, under ideal condition, the 4 mm Plossl lens should still work (1000/4 =
    250), but it really doesn't at all - the viewing is terrible, even last
    night. You may be right about atmospheric conditions, as I am north of DC
    looking south over the city, with all the haze, smog, etc., but last night
    the air was clearer than I can remember in a long time - when I got home,
    got out of the car and saw the stars, it was quite a shock (in summer they
    are almost invisible around here!)

    On the other hand, the 10 mm lens that came with the scope was really clear
    (100x magnifification). So I still wonder if I have a problem with lens
    quality?

    Alan






    "JAS" <maxleonard@hotmail.com> wrote in message
    news:brrvmk01d9n@enews3.newsguy.com...
    eye
    as
    turbulence
    or
    in
    multiplied
    scope.
    maximum
    the
    is
    a
    than



  5. #5
    Ray Porter's Avatar
    Ray Porter Guest

    Default Meade Value Pack Plossl eyepieces

    Hi Alan,
    The original responder is correct. There's nothing wrong with the Meade
    Plossl eyepieces. I've used both the Series 3000 Plossls and the Series
    4000 Super Plossls with no problem with a variety of scopes. I suspect
    you're still facing a seeing condition problem. You have to consider more
    than just how clear the sky is (transparency). You also have to consider
    how stable the air is and this second factor is more important for high
    power, solar system observing. If the air is moving around a lot, even in
    the upper atmosphere where you can't detect it directly, you're not going to
    be able to approach the theoretical magnification limit of your telescope.
    If the stars appear to be twinkling, it's probably not an ideal night for
    high power, planetary observing. Strangely enough, a little haze and lower
    transparency is often a good sign that the evening is right for this type of
    observing. A little haze won't really interfere with viewing the planets
    and it almost always means the air mass is stagnant and very stable.

    I also have an 8" scope (LX90 8" SCT) and have owned a variety of scopes
    over the years. I've only been able to approach that limit with my scope a
    few times in the past 10 years (less than once or twice a year) and I live
    in central NC where conditions aren't all that different from your location.
    In general, my best viewing is at about 180x-230x. If you're close enough to
    DC to really be looking over the city, all the heat rising from the
    buildings and concrete is going to make things even worse for you. You're
    probably not going to find more than 2 or 3 times per year when you're going
    to able to profitably use that 4mm. On most nights, you're probably going
    to start seeing image degradation if you exceed 25x-30x per inch of aperture
    (in other words, your 10mm eyepiece is probably going to be your most use
    ocular).

    Clear skies,
    Ray Porter

    "AK" <a.kolnik@delete-this-part-that-stops-spam.verizon.net> wrote in
    message news:lLsEb.36959$xO.27@nwrddc02.gnilink.net...


    =
    clear
    that
    causing
    "ring"
    most
    8-inch
    your
    you
    I
    can
    rings.
    the
    mm
    that
    simply
    even
    over
    with



  6. #6
    Astronut's Avatar
    Astronut Guest

    Default Meade Value Pack Plossl eyepieces

    One of the biggest issues is the collimation on these scopes. In order
    to achieve the 1000mm focal length, a Barlow lens is used in the
    focusing tube. While I don't profess that this process works, and you
    may end up with a worse view of the night sky than when you started, it
    seems to have worked for this person.
    http://www.grcooperjr.com/_disc2/00000029.htm

    A local astronomy shop, where the owner is a 15 year Meade field rep.,
    had worked on the 114GT for an entire day, before getting it collimated.
    This can make a BIG difference when viewing at higher magnification.

    I'm thinking of buying one as a second scope for my night sky tours,
    just to take the load off my LX-200 10" GPS/UHTC scope, and allow for
    more people on the tour at one time. I've looked through one about 5 or
    6 times now, and feel I have enough experience with telescopes that
    collimation on this won't be a problem (I have owned 11 telescopes in
    the past 22 years). Particularly now that I know the steps to get the
    mirrors properly placed.

    This is a good short-tube, fairly wide field scope, at f/8.7. So it will
    provide a slightly wider field than my F/10 LX-200.



    --
    Gil Tennant
    Night Sky Tours - We bring the Universe to you
    www.nightskytours.ca


    "AK" <a.kolnik@delete-this-part-that-stops-spam.verizon.net> wrote in
    message news:lLsEb.36959$xO.27@nwrddc02.gnilink.net...
    my
    (1000/4 =
    last
    of DC
    night
    home,
    they
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    and that
    ice
    temperature
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    also
    most
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    480X;
    480X
    eyepiece =
    using your
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    eye
    disappointed. Is
    view
    and the
    25 mm
    that
    simply
    even
    sky over
    was with
    better


  7. #7
    AK's Avatar
    AK Guest

    Default Meade Value Pack Plossl eyepieces

    Thanks - I appreciate all the thoughtful replies.

    Looks like my 10 mm will be my best lens - actually, its very crisp, just
    hoped to get more detail via more magnification with the other lenses. But,
    clearly, as one might expect, the other factors outweigh the high
    magnification.


    "AK" <a.kolnik@delete-this-part-that-stops-spam.verizon.net> wrote in
    message news:lLsEb.36959$xO.27@nwrddc02.gnilink.net...
    =
    clear
    that
    causing
    "ring"
    most
    8-inch
    your
    you
    I
    can
    rings.
    the
    mm
    that
    simply
    even
    over
    with



  8. #8
    OG's Avatar
    OG Guest

    Default Meade Value Pack Plossl eyepieces


    "AK" <a.kolnik@delete-this-part-that-stops-spam.verizon.net> wrote in
    message news:NaDEb.41198$xO.30346@nwrddc02.gnilink.net...
    But,

    Hi Alan,
    I've got a similar set up to yours with a Meade 4504 114mm, though mine is a
    long tube.

    Using your Barlow wisely can be a good idea, Use your 25 and 10mm EPs for
    most work and your barlow gives you a quick and easy way of checking whether
    its worth breaking out the 6mm and 4mm EPs as well. Somehow it's much
    easier to keep a barlow to hand rather than getting out 2 extra EPs.

    However I would recommend checking the collimation - I know my collimation
    is slightly out, and I can't get much out of my 6.7mm EP at the best of
    times.

    All the best




 

 

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