Page 1 of 2 12 LastLast
Results 1 to 10 of 20
  1. #1
    Pete Rasmussen's Avatar
    Pete Rasmussen Guest

    Default Anybody used the GSO 50mm SuperView in 6" F-8 Achro?



    Seems there isn't any worthy review material so to speak about this
    2.00" 5-element FMC eyepiece. The number crunch suggests a great
    match up to F-8 and longer. With a common 6" F-8 Chinese Achro it
    will give 24x and ~2.25° TFOV with 6.25mm exit pupil. That would be
    rather ideal for large objects viewed straight ahead (ie. Double
    Cluster, Great Andromeda galaxy, etc.). Any helpful comments to share
    about this model from you folks?

    Thx kindly in advance.

    Pete

  2. #2
    RichA's Avatar
    RichA Guest

    Default Anybody used the GSO 50mm SuperView in 6" F-8 Achro?

    On Fri, 26 Nov 2004 11:35:11 -0600, Pete Rasmussen
    <eye_petes@arkansas.net> wrote:


    You must have great skies!

    I haven't use it but I'm wondering what it's benefit is, apart
    from field size?

    Even though you'd have the wide field, the amount of detail you'd
    lose due to lack of magnification would be appalling.
    I've got a 55mm UO Plossl and the only time I use it is as a finder
    eyepiece for bright objects, stictly because of FOV.
    But I'm amazed that these $80 2" eyepieces can work as well as they
    do. I remember the first cheap 2" offering, the Optilux. What a dog.
    -Rich

  3. #3
    Jon Isaacs's Avatar
    Jon Isaacs Guest

    Default Anybody used the GSO 50mm SuperView in 6" F-8 Achro?

    >). Any helpful comments to share

    No suggestions, I am just curious what the TFOV might be with this eyepiece. I
    found that with the SuperView 42mm the true FOV corresponded to a 56degree AFOV
    rather than the advertised 65 degree.

    None the less, I think the 42mm is still a decent eyepiece.

    jon


  4. #4
    Pete Rasmussen's Avatar
    Pete Rasmussen Guest

    Default Anybody used the GSO 50mm SuperView in 6" F-8 Achro?

    On Fri, 26 Nov 2004 20:03:51 -0500, RichA <none@none.com> wrote:


    They are Ok but not real dark unless traveling a mile out of town.


    A 6mm exit pupil eyepiece with FMC and baffled optics is about the
    limit under the most transparent urban night skies here. The light
    pollution in my small town is getting worse though.

    The benefit of a 50mm eyepiece is the often flat, perfectly corrected
    FOV with objects offered in narrower periferal field.


    Not really for a number of large objects under dark skies. For
    example it is my opinion the double cluster summarily looks it's best
    at 21-24x. Diffuse M-31 and satellite galaxies can be viewed brightly
    and more in front of the observer.


    Never tried the Optilux. The Burgess 26mm, 32mm, and 38mm in 2" SWA
    series for $70 and Owl Services 30mm, 42mm and 50mm in 2" SV series
    for $50 probably offer the best promise in overall quality on the
    cheap.

    Pete

  5. #5
    Pete Rasmussen's Avatar
    Pete Rasmussen Guest

    Default Anybody used the GSO 50mm SuperView in 6" F-8 Achro?

    On 27 Nov 2004 14:47:05 GMT, jonisaacs@aol.com (Jon Isaacs) wrote:

    Hey Jon,


    I got 64° for it *freestanding* under differing methods of measure. I
    think I may know why you got your different results. First there is
    no field stop perse it is the ID edge of the very bottom of 2" barrel
    not the smaller dia. lens retainer ring found just under the field
    lens. Secondly as my review back on March 3rd indicated:

    http://groups.google.com/groups?hl=e...04ax.com#link1

    The field stop becomes restricted dia. by the smaller aperture of a 2"
    star diagonal's eyepiece seat. I got 58° in that situation which is
    about the same as your 56° finding.

    Pete

  6. #6
    Jon Isaacs's Avatar
    Jon Isaacs Guest

    Default Anybody used the GSO 50mm SuperView in 6" F-8 Achro?

    >I got 64° for it *freestanding* under differing methods of measure. I

    Well, I have a hard time visualizing this situation, ie the clear aperture of
    the field lens is 41mm and yet the FOV is supposed to correspond to a
    significantly larger field stop...


    This has been suggested before.

    A couple of things I did to address the issue.

    1. Tried to measure the eyepiece seat diameter of the TV 2 inch Everbright
    diagonal I used for my measurement, it seems to be between 44mm and 45mm which
    would be sufficient for a 61 degree AFOV.

    2 I also took the time to measure the TFOV with 2 different Newtonians using
    some bright stars near the ring nebula. There are some nice bright stars which
    seemed ideal for this, just slightly less than 2 degree seperation.

    I did this with no Paracorr and I ended up with the same result, 56-57 degrees.
    I tried to maximize the field of view by looking at extreme eyepiece angles.

    jon




  7. #7
    Pete Rasmussen's Avatar
    Pete Rasmussen Guest

    Default Anybody used the GSO 50mm SuperView in 6" F-8 Achro?

    On 01 Dec 2004 00:26:37 GMT, jonisaacs@aol.com (Jon Isaacs) wrote:


    Do these to make visualization easy...

    Unscrew and remove the barrel and see how much larger the AFOV
    becomes.

    Another trick is under lighted conditions look into the eyepiece
    normally while placing a toothpick at the end of barrel ID. You will
    see it in focus. That is the field stop area.


    It's true.


    Yours seems maybe a larger opening diagonal than the one I had at the
    time.


    Not sure why you are not getting a wider AFOV measure by the stars
    using a Newtonian but I assure you the 42mm SV I had was about 64° due
    its existing barrel. I would tend to believe the 50mm SV may face the
    same issue.

    Pete


  8. #8
    Jon Isaacs's Avatar
    Jon Isaacs Guest

    Default Anybody used the GSO 50mm SuperView in 6" F-8 Achro?

    >

    I tried this last night with my 10 inch F5 Newtonian. The fields of view were
    exactly the same size.

    I am going to play around with some simple ray tracing to see if it makes sense
    to me that the Field of view can be larger than the clear aperture would seem
    to allow.

    jon


  9. #9
    Pete Rasmussen's Avatar
    Pete Rasmussen Guest

    Default Anybody used the GSO 50mm SuperView in 6" F-8 Achro?

    On 04 Dec 2004 15:15:04 GMT, jonisaacs@aol.com (Jon Isaacs) wrote:


    Sorry, I wasn't clear. What I meant to suggest was look into the
    eyepiece *freestanding*...not placed in an instrument. The purpose is
    to show that the eyepiece barrel is indeed the point of restriction of
    the AFOV. There is no association due the lens retainer ring located
    in front of the entrance aperture. This experiment will answer your
    pending question


    The only way to know how this eyepiece behaves is to take it apart,
    measure and ray trace it specifically. The smallish entrance aperture
    apparently has no effect to limit field size.

    Pete

  10. #10
    Jon Isaacs's Avatar
    Jon Isaacs Guest

    Default Anybody used the GSO 50mm SuperView in 6" F-8 Achro?

    >The only way to know how this eyepiece behaves is to take it apart,

    The one I tested seemed to behave differently than the one you tested....

    Could be they are not the same eyepiece...

    But I would like an explanation of why this eyepiece only provides a 56 degree
    Apparent FOV in a Newtonian with a 2.5 inch diagonal...

    jon

 

 
Page 1 of 2 12 LastLast

Similar Threads

  1. 50mm ep for 6" dob
    By Emu in forum Dobsonian Telescopes Forum
    Replies: 8
    Last Post: 11-24-2009, 06:47 PM
  2. Clavius with 6" ACHRO and Registax
    By Lotz in forum Amateur Astronomy Forum
    Replies: 0
    Last Post: 02-18-2008, 09:09 PM
  3. Copernicus with 6" ACHRO
    By Lotz in forum Amateur Astronomy Forum
    Replies: 8
    Last Post: 02-18-2008, 05:51 PM
  4. 6" achro or 8" newt for DSO's?
    By RKroeppler in forum Amateur Astronomy Forum
    Replies: 20
    Last Post: 04-05-2004, 12:58 PM
  5. GSO SuperView 42mm 68° 2" Eyepiece - A Feverish Indoor Review
    By Pete Rasmussen in forum Amateur Astronomy Forum
    Replies: 2
    Last Post: 03-06-2004, 12:08 AM

Tags for this Thread

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •  
Powered by vBulletin® Version 4.2.0
Powered by vBulletin®
All times are GMT. The time now is 07:42 PM.