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Bresser 60° Plossl range?

Discussion in 'Eyepieces, Barlows, and Filters' started by Mak the Night, Jan 21, 2017.

Bresser 60° Plossl range?

Started by Mak the Night on Jan 21, 2017 at 7:02 AM

52 Replies 742 Views 0 Likes

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  1. Dave In Vermont

    Dave In Vermont Well-Known Member

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    No - but I like that one better!

    I have little doubt it will be on the shelves in 10 years.

    Dave
     
  2. Mak the Night

    Mak the Night Well-Known Member

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    More like 10 months if Google make it. Of course, the downside is that it will be virtual lol.
     
  3. Eduardo Costa

    Eduardo Costa Active Member

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    Hi!

    Let me talk about first post.

    I believe this is a "new" edition Meade Plossl 5 elements 60 degrees.
    It's a Erfle / like Erfle 5 elements. I don't know why is called Plossl.
    Some people like it, but I hated my experience using Meade Plossl 5 elements.
     

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  4. Mak the Night

    Mak the Night Well-Known Member

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    I think they get labelled as 'Plossls' because of marketing trends. As I understand it, an Erfle is a form of modified Plossl with an added fifth element (usually between the doublets).

    That Meade looks quite nice though, what was it exactly that made you dislike it? I think they probably work best in scopes f/6 and slower.
     
    Last edited: Feb 28, 2017
  5. Eduardo Costa

    Eduardo Costa Active Member

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    There are several designs of eyepieces that use convex plane dubletos, variations of these dubletos and biconvex elements.

    A variation of Erfle with 5 elements can use two of these doublets and biconvex element between them. Astroplanar (Celestron Ultima), Erfle 5 (Wide Angle 60 degress), Long Eye Relief (Vixen SLV) are eyepieces that have elements with similarity with two dublets and biconvex between.

    However, there are differences in curvatures, thicknesses and refractive index. We can not simply say that an Erfle 5 is a different Plossl. In schematic drawings they have some similarity, but other optical properties make these eyepieces different.

    What I did not like?

    There is some field curvature that bothers me. This point is subjective, of course, there are those who do not care so much about field curvature.

    Even in reflectors, the eyepiece delivers a bit of lateral color, especially at the edges.

    There's a lot of coma on the edges of the eyepiece.

    Placing Aldebaran and Hiades on opposite edges of the eyepiece field and observing the central field deliver these 3 defects, even using F / 8 telescopes.

    There are eyepieces 60 degrees worse and better than these. But for a little more money, six-element 60-planet planetary like Celestron XCel LX, Meade HD 60, Paradigm do a better job.
     
  6. Mak the Night

    Mak the Night Well-Known Member

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    Eyepiece development is complicated.

    erf1.jpg
    erf2.jpg

    I think any design compromises something and the history and development is a long and complicated one.

    erf3.jpg
    erf4.jpg

    Evolution of the Eyepiece ~ C.J.B. Lord

    It's interesting to hear about your problems with those Meade EP's though.
     
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  7. Eduardo Costa

    Eduardo Costa Active Member

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    Agree!

    Historical development puts Plossl as a Mother and Grand Mother for several eyepiece designs. However, each eyepiece design has particular aspects and this becames a new eyepiece.

    Even TV Plossl is a difference eyepiece comparing ordinary Plossl, unless to me. There is a few difference curvature at one doublet. Brandon has a small difference and it is considered a other eyepiece.

    Erfle and their derivatives are difference eyepieces too.

    The troubles with Meade "Plossl" 60 is not end of the world. Just are better options for your money.
     
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  8. Dave In Vermont

    Dave In Vermont Well-Known Member

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    I guess I'll splash a few colors on the walls in this thread.....


    EP's Schematic PNG.png

    This prints out well,

    Dave
     
  9. Mak the Night

    Mak the Night Well-Known Member

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    I came to the conclusion a long time ago that everything with astronomical optics is a compromise of sorts. Thanks for the head's up on the Meade 60° 'Plossl' though. They may work well in slower scopes, it's usually the way with modified Erfle designs.
     
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  10. Mak the Night

    Mak the Night Well-Known Member

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    I so want that as a wallchart!
     
  11. Dave In Vermont

    Dave In Vermont Well-Known Member

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    I put the print-out on my wall here. Clashes well! :D

    Dave
     
  12. Don Pensack

    Don Pensack Vendor

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    These are simply re-packaged and re-badged eyepieces JOC has made since the '90s.
    They were originally sold as the Meade Series 5000 "Super Plössls". The AFOV is 60° but the outer 10° isn't very good.
    The design pushed the AFOV farther than it should have gone.
     
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  13. Mak the Night

    Mak the Night Well-Known Member

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    Oh right, thanks Don. I suspected some Meade/JOC connection. The outer 10° isn't too bad in a slow scope, particularly an f/13.8 one. I got a pair of 20mm for my bino.

    WO bino 20mm Plerfles.jpg

    I haven't had a real chance to test them yet but they seem competent. I chose them because they have smooth brass drawtubes which sit well in the WO dioptres and the EP's themselves are relatively small and compact (and fit in my bino case lol).
     

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