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Thread: Eyepiece Advice

  1. #1
    Pat Dotson's Avatar
    Pat Dotson Guest

    Default Eyepiece Advice

    With a target price of ~$50 each, what are the best 4 and 5 mm
    eyepieces to be had for planetary viewing?

    I have the Konus version of the Synta 120 mm refractor (F/8.3). It is
    collimated, the focuser is aligned, and it star tests well. My
    current highest power EP's (10mm and 6.5 mm) produce 100X and 150X,
    and I am very happy with the view at those magnifications. I added a
    GTO 2X Barlow to get 200X and 300X, but with the Barlow the view isn't
    good at all. The Barlow seems to have a lot of internal reflections
    so that all contrast is lost, and the image is dim and hazy. I really
    feel that the Barlow is at fault here, and that especially at 200X
    this scope should do well.

    Rather than invest in another Barlow, I want avoid any further
    obstructions of extra glass by buying one 4 mm and one 5 mm eyepiece.
    The only other consideration is eye relief. More is better for me.

    Any advice is appreciated!


  2. #2
    Pat Dotson's Avatar
    Pat Dotson Guest

    Default $50 Eyepiece Advice

    Thanks. The UO ortho sounds like the right solution. Plus, it's
    available in both a 4 and 5 mm configuration. How is the eye relief
    in those?

    My 6.5 mm is one of the GTO's, and it's not bad. The eye relief is
    tight, though. The low cost GTO's only come in a 4 mm version. I
    think one of the higher priced versions is available in 5 mm.

    Any other possibilities?

    wfoley2@wmconnect.comp.q (FoneBone) wrote in message

    Pat Dotson wrote:

  3. #3
    Brian Tung's Avatar
    Brian Tung Guest

    Default $50 Eyepiece Advice

    Pat Dotson wrote:

    Almost non-existent. If you're observing the planets in a motor-driven
    scope, however, you can set your eye well back beyond the nominal eye
    relief, and still see the planet just fine. The field of view will be
    much smaller than nominal, also, but with a motor-driven scope, that
    shouldn't matter too much (except for aesthetics). I use this tactic
    with my 9 mm ortho all the time.

    Brian Tung <>
    The Astronomy Corner at
    Unofficial C5+ Home Page at
    The PleiadAtlas Home Page at
    My Own Personal FAQ (SAA) at

  4. #4
    Edward's Avatar
    Edward Guest

    Default $50 Eyepiece Advice

    The eyerelief cited by K. Kohki is 80% of the focal length with the
    exception of the 4mm which has an eyerelief of 3.5mm.


    "Brian Tung" <> wrote in message

  5. #5
    Joe S.'s Avatar
    Joe S. Guest

    Default Eyepiece Advice

    I have a 5mm Nagler and 4mm and 5mm University Optics orthos.

    The Nagler cost almost as much as a low-end scope.

    The UO orthos are around $60.00 each. I use the orthos more than I use the
    Nagler. The eye relief is non-existent -- you get your eye right down on
    the eyepiece, almost on the glass -- the lack of eye relief has never
    bothered me -- and the field of view is a bit less than the Nagler but
    objects are bright and you can't go wrong with the price of the UO orthos.


    Joe S.

    "Pat Dotson" <> wrote in message om...

  6. #6
    Pat Dotson's Avatar
    Pat Dotson Guest

    Default $50 Eyepiece Advice

    Thanks again for the comments. I'm sold on the UO pieces. The only
    decision left is, HD or classic? The conical design of the classic is
    appealing, but the HD seems to have the edge in performance.

    I only see the classic listed on the web site. Are the HD's

  7. #7
    Alan W. Craft's Avatar
    Alan W. Craft Guest

    Default $50 Eyepiece Advice

    On 29 Oct 2003 19:18:48 -0800, (Pat Dotson) wrote:

    You will LOVE the classic 4mm, and its truncated top.

    If it's a toss-up between the 4mm and the 5mm, get the 4mm,
    as I have both; it's superior.

    I've never had an HD, but have read that they're only
    slightly superior to the classic, and at best. The truncated
    tops, I feel, would certainly outweigh that negligibility,
    particularly when one considers the HD series's
    extra cost.


  8. #8
    Alan W. Craft's Avatar
    Alan W. Craft Guest

    Default $50 Eyepiece Advice

    On 29 Oct 2003 12:52:13 -0800, (Pat Dotson) wrote:

    The 4mm's is short, of course, but with its truncated top
    it's most surprisingly accomodating; in toto, get the 4mm.


  9. #9
    Pat Dotson's Avatar
    Pat Dotson Guest

    Default $50 Eyepiece Advice

    Thanks for the advice.

    I picked up the 4mm and 5mm classic UO ortho. Eye relief is *very*
    comfortable in both, much better than I had expected. They both
    appear to work well with my 120mm F/8 refractor. The views are very
    bright compared to the Barlow/EP combo I was using.

    Unfortunately, because of poor seeing and mostly overcast skies, there
    hasn't been a good opportunity for observing since the EP's arrived.
    Things should clear up by the weekend.

    On another topic, who has the best bargain on Newtonian OTA's? Orion
    has an 8" for $269 that is very tempting, but I think I want at least
    a 10". Are there any 10" OTA's out there available for under $350?

    Alan W. Craft <> wrote in message news:<>. ..

  10. #10
    Alan W. Craft's Avatar
    Alan W. Craft Guest

    Default $50 Eyepiece Advice

    On 5 Nov 2003 12:55:14 -0800, (Pat Dotson) wrote:

    I'm glad you're pleased, as I am, too. Well, almost, as I'm still
    undecided on the 5mm. I've informed the gentleman at University
    that I may exchange it for another of the same focal length, but only
    after I observe with it a bit more, and with my yet-to-arrive Newtonian.

    I had purchased an 11mm TeleVue Plossl, and promptly sent
    it back as its eye relief was virtually nonexistent. I have a 40mm
    TeleVue Plossl, that's not too bad really, but I dare not consider
    anything shorter, or at least as short as that 11mm; dreadful.

    I'd like a 32mm 2" ocular now, and maybe one even longer,
    as I recently found that I have at least 7.5mm dark-adapted pupils,
    if not 8mm, and at the age of 39, hence that 55mm may not be so
    unreasonable after all. The prospect's rather exciting.

    Yes, of course, as the orthoscopic design consists of only
    four elements. I do like the simpler designs very much. I have
    12mm and 16mm Konigs which are wide-field designs also
    employing four elements. They're...fair-to-middling, at least.

    Orion's may very well be about as inexpensive as they get, and
    I understand that the quality is quite good for the price, and beyond

    If I considered a 10", then I'd ask myself, "Why not a 12.5, or
    even a 16"," but that's as far as I'd go, personally.

    Of course, we mustn't neglect the mount...

    What sort of mount had you envisioned for the 10"?



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