Re: 2" 90° Apparent Field Eyepieces Announced

From: brian (brianc1959_at_aol.com)
Date: 07/02/04 

Date: 2 Jul 2004 07:07:46 -0700

shneor@my-deja.com (Shneor Sherman) wrote in message news:<9dedb1fb.0406300643.2e10efd6@posting.google.com>...
> jonisaacs@aol.com (Jon Isaacs) wrote in message news:<20040629175818.11708.00000633@mb-m11.aol.com>...
> > >My experience with Burgess has been excellent value for the money. But
> > >I do wonder about the optical characteristics of this eyepiece.
> > >
> > >Clear skies,
> > >Shneor Sherman
> >
> > Probably best to take the wait and see attitude if something isn't currently
> > yet available. Burgess Optical has been somewhat optimistic in the past about
> > delivery dates...
> >
> > Jon
>
> Here's some more info from Bill Burgess: It's a 7-element design, all
> ED glass,"broadband multicoatings on all air-to-glass surfaces", and
> pinpoint stars to the edge down to f/3.5. Availability is at least 60
> days out.
>
> The part about pinpoint stars to the edge of a 90° apparent field 29mm
> eyepiece sounds very attractive. Maybe some of our eyepiece design
> mavens can tell us why this is either impossible or comes at the price
> of field curvature, loss of contrast or some other desirable optical
> characteristic. Or not.
>
> Clear skies,
> Shneor Sherman

Don Dilworth demonstrated that its possible to build a 90deg. eyepiece
with extraordinary performance. See U.S. Patent 4,720,183. The
designs published in this patent are among the highest performance
eyepieces I've ever seen. Much better than even the published Nagler
designs. No ED or high-index lanthanum type glasses are needed. The
only drawback is size. A 29mm focal length would have some elements
as large as 4" in diameter. Below is the patent prescription for a
15.9mm Dilworth:

Surf Radius Thickness Glass Diameter
 OBJ Infinity Infinity 0
 STO Infinity 16.367 3.984463
   2 -46.13459 1.294 1.805180,25.430 34
   3 59.64817 12.152 1.638540,55.420 39
   4 -25.6419 0.4099999 39
   5 104.509 14.0534 1.620410,60.320 60
   6 -57.40218 24.826 60
   7 50.58608 12.4375 1.620410,60.320 62
   8 4353.534 0.4099999 62
   9 23.4904 10.75047 1.620410,60.320 45.2
  10 26.7368 11.6589 40
  11 -83.8454 3.57986 1.620040,36.370 40
  12 23.38768 14.06033 32
  13 33.9786 5.868849 1.846660,23.830 33
  14 221.1201 4.122499 33
  15 -46.2614 3.39373 1.539960,59.710 33
  16 56.31179 -27.43597 33
 IMA Infinity 28.58338

Brian
www.caldwellphotographic.com

Relevant Pages

  • Re: 2" 90° Apparent Field Eyepieces Announced
    ... > eyepiece sounds very attractive. ... with extraordinary performance. ... See U.S. Patent 4,720,183. ... designs published in this patent are among the highest performance ...
    (sci.astro.amateur)
  • Re: Uli Behringer responds to those "rip off" claims
    ... point about your Behringer article. ... cheap little mixer has 'soul'. ... then I had a little garage company and believed Aphex's patent was ... How Behringer designs products: Our R&D department, which I head, ...
    (rec.audio.pro)
  • Re: Announcement: Evolution based improvement of (at least web)images (A Patent Buster)
    ... Player's visualizations - the crazy patterns that play when you play ... The text formulation present in patent claims, ... creating audio and / or visual designs k n o w n for it... ... * Use 'Magnify'-links to save your images locally; ...
    (sci.image.processing)
  • Re: Review of TMB Super Monos with Valery on board
    ... The monocentrics, when proper executed, are certainly fine planetary ... " While talking with Thomas Baader several years ago about eyepiece designs, ... we discussed the original Zeiss monocentric vs. the newer Abbe Orthoscopic ...
    (sci.astro.amateur)
  • Re: UK distributor wants me to stop my parallel imports
    ... Designs and Patents Act 1988. ... >>Firstly drugs are not covered by copyright but rather patent. ... >>The OP doesn't say what they are importing - I have assumed it ... manufacturers content on my website. ...
    (uk.legal)