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tech1
member
Reged: 09/30/07
Posts: 58
Loc: Franklin Ohio
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Ok,this is my 3rd question posted on eyepieces,how many elements make a good eyepiece? Are more better?
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Lawrence Sayre
Post Laureate
Reged: 10/16/04
Posts: 3677
Loc: N.E. Ohio
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Take this purely with a grain of salt, but in general:
3-4 seem to be sufficient for ~30-50 degrees AFOV.
5-6 seem to be sufficient for ~51-60 degrees AFOV.
6-8 seem to be sufficient for ~61-82 degrees AFOV.
9+ are likely needed for ~100 degrees AFOV.
That said, the number of elements do not correlate with the quality of the eyepiece. Many more factors are required than just element count.
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My philosophy, in essence, is the concept of man as a moral being, with his own happiness as the moral purpose of his life, with productive achievement as his noblest activity, and reason as his only absolute.
Ayn Rand (in the appendix to 'Atlas Shrugged')
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jrbarnett
Carpal Tunnel
Reged: 02/28/06
Posts: 2635
Loc: Petaluma, CA
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The answer is....drum roll please...it depends!
It depends on (a) what scope you are using, (b) what objects you are viewing, (c) whether you must wear glasses when observing, and (d) what your budget is.
For example, if you have a really nice long focus achromat on a tracking mount, don't need to wear glasses, have a limited budget, and mostly look at the moon, planets and double stars, perhaps a good quality 4-element Orthoscopic or Plossl would be best for you. If, however, you have a fast f/4.5 10" Dobsonian with manual tracking, like to view extended nebulae, have great eye sight and have a lot of dough saved up, perhaps a 7 or 8 element ultra wide field like a Type 5 Nagler is best for you.
There really is no one answer to your question.
Regards,
Jim
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"The Cosmos is all that is or ever was or ever will be. Our feeblest contemplations of the Cosmos stir us — there is a tingling in the spine, a catch in the voice, a faint sensation, as if a distant memory, of falling from a height. We know we are approaching the greatest of mysteries." - Carl Sagan
Edited by jrbarnett (08/12/08 11:22 AM)
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GeorgeDuke
Pooh-Bah
Reged: 04/24/03
Posts: 1143
Loc: PARADISE! (So.Florida)
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I think a lot has to do with your definition of "good eyepiece".
These days with the materials and technology available, most eyepieces can be considered "good".
First you have to qualify good, good as apposed to excellent?
Good for what application?
I have some 2" GSO Kellner 3 element eyepieces which I consider to be very good! I paid $35 each new and being a limited resources kind of guy I am happy with them.
Would I like Naglers? sure if you know of any for $35 each!
I have a set of X-Cels which have 6 elements and cost $40 each and I think they are "good".
Most reading this would not agree with me and tell me I need to pay at least $300 for a "good" eyepiece and maybe they are correct.
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George
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LX200GPS 203mm f10
StellarVue SV102ED2 Feathertouch Ser#0018
Celestron 130mm f15.4 Mak
LXD75 GOTO with Orion 16" pier extension
Desert Sky DSV1 dual head ALT-AZ mount
Baader Hyperion 8mm ,13mm, 21mm and 8-24mm Zoom
2" GSO ED barlow, Orion 2" Prism Diag. 2" WO Dielectric
Chinese Scopes, Chinese Eyepieces, Chinese Wife, Love them all!
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Mr. Mike
scholastic sledgehammer
Reged: 11/08/05
Posts: 855
Loc: Churchville, NY
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Quote:
I think a lot has to do with your definition of "good eyepiece".
These days with the materials and technology available, most eyepieces can be considered "good".
First you have to qualify good, good as apposed to excellent?
Good for what application?
I have some 2" GSO Kellner 3 element eyepieces which I consider to be very good! I paid $35 each new and being a limited resources kind of guy I am happy with them.
Would I like Naglers? sure if you know of any for $35 each!
I have a set of X-Cels which have 6 elements and cost $40 each and I think they are "good".
Most reading this would not agree with me and tell me I need to pay at least $300 for a "good" eyepiece and maybe they are correct.
You certainly do NOT have to pay $300++ dollars for an eyepiece for it to be good. Heck, there are plenty of EPs for $200 or less that are very good performers!
That being said, the higher-end stuff probably works better in "difficult" scopes as in fast f-ratios. Otherwise, the performance gap between the best and middle-tier stuff is shrinking from what I have found.
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Stellarvue NG 80mm ED
Meade 7x50 Binos
Pentax XW 5mm
Meade 5K UWA 8.8mm
Vixen LVW 13mm
Vixen LVW 22mm
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Deep13
Pooh-Bah
Reged: 01/25/05
Posts: 1454
Loc: NE Ohio
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Quote:
Ok,this is my 3rd question posted on eyepieces,how many elements make a good eyepiece? Are more better?
yes and no
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Preserve the night sky. Join the Internat. Dark Sky Assn. for less than a cheap eyepiece.
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