Dismiss Notice
We were experiencing issues with a server migration and upgrade to the underlying platform. Everything should be up and running now, but if you notice any issues with the site please head over to Report and Issue Forums to let us know. If you are unable able to do so, free to email me directly atgeorge@astronomyconnect.com. Thank you for your patience and understanding.
-George

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

53 Replies 1458 Views 0 Likes

Reply to Thread Post New Thread
  1. Dave In Vermont

    Dave In Vermont Well-Known Member

    Joined:
    Jan 5, 2016
    Posts:
    1,236
    Trophy Points:
    83
    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

    Joined:
    Jul 10, 2016
    Posts:
    1,734
    Trophy Points:
    83
    Location:
    Lloegr
    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

    Joined:
    Sep 5, 2015
    Posts:
    33
    Trophy Points:
    8
    Location:
    Sao Paulo, Brazil

    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.
     

    Attached Files:

  4. Mak the Night

    Mak the Night Well-Known Member

    Joined:
    Jul 10, 2016
    Posts:
    1,734
    Trophy Points:
    83
    Location:
    Lloegr
    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

    Joined:
    Sep 5, 2015
    Posts:
    33
    Trophy Points:
    8
    Location:
    Sao Paulo, Brazil
    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

    Joined:
    Jul 10, 2016
    Posts:
    1,734
    Trophy Points:
    83
    Location:
    Lloegr
    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.
     
    Eduardo Costa likes this.
  7. Eduardo Costa

    Eduardo Costa Active Member

    Joined:
    Sep 5, 2015
    Posts:
    33
    Trophy Points:
    8
    Location:
    Sao Paulo, Brazil
    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.
     
    Mak the Night likes this.
  8. Dave In Vermont

    Dave In Vermont Well-Known Member

    Joined:
    Jan 5, 2016
    Posts:
    1,236
    Trophy Points:
    83
    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

    Joined:
    Jul 10, 2016
    Posts:
    1,734
    Trophy Points:
    83
    Location:
    Lloegr
    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.
     
    Eduardo Costa likes this.
  10. Mak the Night

    Mak the Night Well-Known Member

    Joined:
    Jul 10, 2016
    Posts:
    1,734
    Trophy Points:
    83
    Location:
    Lloegr
    I so want that as a wallchart!
     
  11. Dave In Vermont

    Dave In Vermont Well-Known Member

    Joined:
    Jan 5, 2016
    Posts:
    1,236
    Trophy Points:
    83
    I put the print-out on my wall here. Clashes well! :D

    Dave
     
  12. Don Pensack

    Don Pensack Vendor

    Joined:
    Nov 30, 2015
    Posts:
    39
    Trophy Points:
    8
    Location:
    Los Angeles
    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.
     
    Mak the Night likes this.
  13. Mak the Night

    Mak the Night Well-Known Member

    Joined:
    Jul 10, 2016
    Posts:
    1,734
    Trophy Points:
    83
    Location:
    Lloegr
    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).
     
  14. Mak the Night

    Mak the Night Well-Known Member

    Joined:
    Jul 10, 2016
    Posts:
    1,734
    Trophy Points:
    83
    Location:
    Lloegr
    I finally got some viewing in with the 5.5mm Bresser 60° Plossl. It gave me just under 164x for an 0.79mm exit pupil and a TFOV of almost exactly 22 arc minutes. The telescope was an f/6.9 13cm Newtonian with a Baader helical focuser on an EQ2 mount. The main lunar targets were Schroter’s Valley, Montes Harbinger, the Schickard crater and their corresponding areas. I viewed both with and without a Baader Neodymium and a Solomark Moon & Skyglow filter.

    MONTES HARBINGER.jpg

    On the lunar targets the Bresser performed well compared to other eyepieces I used, including a 7mm Abbe orthoscopic, a 5mm TS Optics Planetary HR and a 4mm Sky-Watcher UWA.

    Bresser 5.5.jpg

    There was no noticeable degradation towards the outer 10° of the FOV with the Bresser. Conditions weren’t ideal though and there were transparency issues with a lot of moisture in the air. The Solomark filter helped a little with contrast in this respect. Also, it acted a bit like a Wratten 82A Light Blue filter which can help highlight detail.

    SCHICKARD.jpg

    The real surprise was with Jupiter. Admittedly only a day after opposition, but the GRS was very visible with the Bresser and detail was very good. On the night of the opposition itself I’d stuck mainly with the 5mm TSO HR EP and didn’t use the Bresser at all. The image of Jupiter with the 5.5mm Bresser was basically as good as with the 5mm TSO, and to me, not far off the 7mm Kokusai orthoscopic.

    GRS1.jpg

    Images of the Moon & Jupiter by courtesy of VMA & CDC.
     

Share This Page