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  1. #1
    Pete Rasmussen's Avatar
    Pete Rasmussen Guest

    Default GSO SuperView 42mm 68░ 2" Eyepiece - A Feverish Indoor Review

    Being at home sick with a cold today, I had the infectious "bug" to do
    some indoor evaluation work with a newly available model Taiwanese
    wide-angle eyepiece I found. I bought it because the offered
    specifications made it seem a potential candidate as budget
    replacement to my University Optics Konig MK-70 40mm.

    To the best of my knowledge this new-to-market Guan Sheng Optical Co.
    product has been advertised for only three weeks now beginning with
    eBay seller adastra4ync. The bid price being set at $69.00 or $79.00
    for "Buy-It-Now" with $8.00 U.S. domestic rate shipping. About a week
    later eBay seller owl1 launched his sales campaign for it at bid price
    $49.00 or $59.00 for "Buy-It-Now" with $6.00 domestic shipping. These
    both are likely record breaking cheap prices for a commercially made
    astronomical telescope eyepiece in this class.

    The outward appearance is clean and speaks of good quality. The
    lettering is white paint embossed reading: GSO SUPERVIEW 42mm 68░ FIVE
    ELEMENTS. It measures 112mm tall with eyecup extended and 55mm for
    major body diameter. There is a 22mm wide diamond knurled rubber grip
    ring midway on the black anodized upper housing. A fold-down rubber
    eyecup is added on top. There is a nicely plated silver colored 2"
    format barrel with safety undercut. It is threaded for standard
    filters. The optics have a desirable dull reflection green lens
    multicoating variation throughout, with 6 air-glass surfaces indicated
    as shown from an external light source. The model comes with a lower
    barrel slide on dust cap and is placed in a gloss black cover
    cardboard box.

    There is also a new very similar looking GSO 50mm model out as well.
    It is sold at the same price point and is specified as having about a
    54░ AFOV.

    To get some highly useful reference points against a well known model,
    I faced the unknown eyepiece head-to-head with my late version
    Japanese made University Optics Konig MK-70 40mm 2" eyepiece. The one
    I own has the full 70░ AFOV vs. 68░ as was found in earlier units that
    were sold. I also used other various eyepiece optics to more closely
    gauge this new models effective AFOV.

    Compared Specifications (GSO SV 42mm / University MK-70 40mm)

    Weight: 320g / 525g

    Entrance Aperture: 40mm / 47.5mm

    Exit Aperture: 34mm / 40mm

    Field Stop: 47mm / 46.5mm

    Interestingly the visibly used field stop location for the GSO 42mm is
    effectively the very bottom edge (entrance ID) of the eyepiece barrel
    itself. For reference, that's where the filter threads are located.
    Holding the eyepiece alone to the eye shows it is vague visually to
    see its circle all at one time. My eye tended to quicky fall below
    the approx. 15mm eye relief margin to then barrel distort the view.

    Once gauged, the effective AFOV measured no more than 64░ with the
    eyepiece freestanding. When placed in my (common) 41.5mm seat
    aperture 2" 90░ mirror star diagonal, the measure then fell to 58░.
    This is well below the advertised (and physically labelled)
    specification of 68░ AFOV.

    Since "under the weather", I wasn't about to head outside to get other
    measures of actual optic system performance. Instead, I opted for
    some brief views out a window with a 100mm f/6 achromat refractor.
    The image given was sharp for approx. 80% from center-to-edge. Not
    bad for the given 58░ apparent field angle of the design. There was a
    slight bit of field curvature also noted.

    At this point I needed to stop and take a rest. Because the
    University MK-70 40mm gives such a vastly larger view, I think I will
    just hang onto it and give the GSO 42mm away to a friend in need.

    Clear skies,


  2. #2
    Leonard's Avatar
    Leonard Guest

    Default GSO SuperView 42mm 68░ 2" Eyepiece - A Feverish Indoor Review

    Pete Rasmussen <> wrote in message news:<>. ..

    Hi Pete ,

    Sure hope your feeling better soon. Thanks for this
    thoughtful evaluation . You are quite an asset to SAA . Looking
    forward to some warmer days .

  3. #3
    Pete Rasmussen's Avatar
    Pete Rasmussen Guest

    Default GSO SuperView 42mm 68░ 2" Eyepiece - A Feverish Indoor Review

    On 4 Mar 2004 13:29:40 -0800, (Leonard) wrote:

    Thanks, Leonard for the well wishes and commendation. The new
    eyepiece seems nice and does have good user eyerelief. Probably very
    sharp with a barlow, too. Looks like we beat your weather it has been
    to 72░ here the other day.

    Clear skies,




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