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  1. #1
    Stephen Tonkin's Avatar
    Stephen Tonkin Guest

    Default Eyepiece design question.



    Can someone help identify this eyepiece design:

    6 elements in 4 groups; from field lens to eye lens they are:

    Biconcave doublet
    Biconvex singlet
    Biconvex doublet
    Convex meniscus with concave side towards eye

    AFoV is about 50º, field is flat, eye relief is about 20mm.

    Some sort of hybrid of a Zeiss Astroplanar and a Nagler Mk1?


    Best,
    Stephen

    Remove footfrommouth to reply

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  2. #2
    brian's Avatar
    brian Guest

    Default Eyepiece design question.

    Stephen Tonkin <news05footfrommouth@astunit.com> wrote in message news:<aaBKN4B+V2KBFwsy@astunit.com>...

    In the patent literature I found:

    1) U.S. 3,233,513 (Zeiss)
    2) JP 06-175,047 (Pentax)
    3) JP 10-319,327 (Nikon)

    There are quite a few others which are very similar, but don't match
    your description exactly. Its almost certainly an internal image type
    eyepiece, like the Nagler and its predecessors.

    Brian
    www.caldwellphotographic.com

  3. #3
    Adam Norton's Avatar
    Adam Norton Guest

    Default Eyepiece design question.

    Stephen,

    This sparse description does not sound like anything very classic. It could
    be a variation of a Nagler especially if the first lens is before the field
    stop. The links below might help you identify which type is most similar.
    Keep in mind that, when designing a lens, nearly any singlet can be improved
    by making it a doublet or by splitting it into two separate lenses. Of
    course more elements are more expensive and create more stray light.

    http://www.brayebrookobservatory.org...fEYEPIECES.pdf
    http://members.shaw.ca/quadibloc/science/opt04.htm
    http://www.cloudynights.com/reviews5/diagrams.htm

    Adam Norton
    Norton Engineered Optics

    (when replying, remove the "REMOVETHIS" from the address)


    "Stephen Tonkin" <news05footfrommouth@astunit.com> wrote in message
    news:aaBKN4B+V2KBFwsy@astunit.com...



  4. #4
    Alexander Dräbenstedt's Avatar
    Alexander Dräbenstedt Guest

    Default Eyepiece design question.


    "Stephen Tonkin" <news05footfrommouth@astunit.com> schrieb im Newsbeitrag
    news:aaBKN4B+V2KBFwsy@astunit.com...


    How about some ASCII-Art in these cases? ;-)
    )|( () (|) ((



    have a look at this microlens array:
    B
    B
    B
    B
    B
    B

    any more ideas?

    Alex



  5. #5
    Helpful person's Avatar
    Helpful person Guest

    Default Eyepiece design question.

    "Adam Norton" <AnortonREMOVETHIS@ix.netcom.com> wrote in message news:<6kQWc.12218$3O3.9234@newsread2.news.pas.eart hlink.net>...

    Actually, it is not true that for by splitting or turning a singlet
    into a doublet will necessarily improve a lens design. For designs
    consisting of more than just a few elements this is often contrary to
    the truth.



  6. #6
    Adam Norton's Avatar
    Adam Norton Guest

    Default Eyepiece design question.

    In the worst case, attempting to split an element or turn it into a doublet
    will simply make no improvement; during optimization, the design variables
    will want to change so that the two elements will effectively merge back
    into a single element. I think this is what you meant when you said that it
    "will not necessarily improve a lens" although in my experience almost any
    lens design can be made more complicated and produce a marginal improvement.
    Of course a "marginal improvement" does not necessarily mean a worthwhile
    improvement. Usually the designer stops tinkering when the practical
    considerations of cost, stray light, etc. outweigh the benefits. This is why
    it is rare to find a lens where you absolutely could not improve its imaging
    performance by making it more complicated.

    My original point was that a classic eyepiece design can be made to look
    more complicated by these types of variations making it difficult to
    determine what type it is.

    Adam Norton


    "Helpful person" <rrllff@yahoo.com> wrote in message
    news:87946313.0408250426.1d6ce1ec@posting.google.c om...

    (snip)


    (snip)



  7. #7
    Helpful person's Avatar
    Helpful person Guest

    Default Eyepiece design question.

    "Adam Norton" <AnortonREMOVETHIS@ix.netcom.com> wrote in message news:<6e5Xc.13023$3O3.12088@newsread2.news.pas.ear thlink.net>...

    Splitting a singlet or making a singlet into a doublet can most
    certainly make the performance of a lens worse. The most common
    reason for this is that for a lens to be manufacturable it must have a
    positive edge thickness. This usually requires an increase in glass
    thickness. For some designs this is extremely detrimental.


  8. #8
    Allan Adler's Avatar
    Allan Adler Guest

    Default Eyepiece design question.

    brianc1959@aol.com (brian) writes:


    I've never seen anyone do a patent search like that before, based only
    on a technical description of the item. Can you explain how you did that?
    --
    Ignorantly,
    Allan Adler <ara@zurich.csail.mit.edu>
    * Disclaimer: I am a guest and *not* a member of the MIT CSAIL. My actions and
    * comments do not reflect in any way on MIT. Also, I am nowhere near Boston.

  9. #9
    John Savard's Avatar
    John Savard Guest

    Default Eyepiece design question.

    On 04 Dec 2004 07:05:40 -0500, Allan Adler <ara@nestle.csail.mit.edu>
    wrote, in part:





    The patent classifications for optical devices are based on the order of
    positive and negative groups.

    John Savard
    http://home.ecn.ab.ca/~jsavard/index.html

  10. #10
    brian's Avatar
    brian Guest

    Default Eyepiece design question.

    Allan Adler <ara@nestle.csail.mit.edu> wrote in message news:<y938y8es1yj.fsf@nestle.csail.mit.edu>...

    I spent 15 years developing a lens design database called LensVIEW.
    There are currently more than 30,000 individual designs in the
    database, all of which have been categorized by me according to a
    system that I devised. I generally find this system more useful than
    the US or International classification systems. For example, one of
    the categories is for eyepieces with an internal image. I can also
    search on a wide variety of optical parameters.

    Brian
    www.caldwellphotographic.com

    (founder of Optical Data Solutions, which publishes LensVIEW)

 

 
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