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Started by Rosebud, 11/06/2004 10:52AM
Posted 11/06/2004 10:52AM | Edited 11/06/2004 10:52AM Opening Post
I am really confused about all the different types of eyepieces available. would someone recommend for me which eyepieces are best to use? I see plossl's, naglars,Kellners, ???? Whats the diff? I currently own a ETX 90mm at. I hope to upgrade later . :S
Posted 11/06/2004 12:13PM #1
Leigh--
That's a huge question. Here's a brief summary, but you can learn a lot more at the sites listed below. Plossls are a 4-element design, typically sharp throughout a 50 degree field, and a good all-purpose eyepiece for the beginner. Orthoscopics typically have a somewhat smaller field (40 to 45 degrees) and are prized as planetary eyepieces. Kellners are a 3 element design, subject to ghosting and poorly corrected at the edges, at least in fast (low f/ number) scopes. Naglers are a proprietary design of televue and are very pricey, delivering 82 degrees of field and sharp pretty much edge to edge, even in fast scopes--the meade ultrawide is a competitor. The televue panoptic line is somewhat less expensive, delivering 68 degrees of field, again very sharp to the edges--competitors include the meade superwide, pentax xw, and speers-waler. Erfles are an earlier wide field design that are usually poorly corrected in fast scopes, but might work well in your etx-90.

1. eyepiece reviews at cloudy nights--there's also a link here (maybe broken) on eyepiece design:
http://www.cloudynights.com/eyepiece.htm

2. general articles on eyepieces and specifications of televue eyepieces at televue's site:
http://www.televue.com/engine/page.asp?cat=2

an eyepiece primer by jay reynolds freeman at excelsis (somewhat quirky):
http://observers.org/beginner/eyepieces.freeman.html

the eyepiece reviews at excelsis:
http://www.excelsis.com/1.0/section.php?sectionid=22

George Golitzin