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Radians, plosses, and naglers..oh my.

Started by gyrocopter24, 09/25/2010 10:11PM
Posted 09/25/2010 10:11PM | Edited 09/25/2010 10:54PM Opening Post
Hi everyone, Just got my first scope! grin First off I want to apologies for the long posting, but here goes.

10" zhumell f4.92
It came with:
Zhumell 32mm eyepiece,
13mm Baader hyperion
moon filter
Skycommander, and so on.

My bio:
Eyeglasses/astigmatism (doesnt really bother me looking through eyepiece).
I’m an ultrasound tech, so I have a train eye for detail and I prefer a quality eyepiece for clarity and details. Price is not too big of an issue right now…. But I will buy use, if I can and get just what i need and not what I want.
I will be using the scope for everything right now..planetary, DSO.
I've been coming to this web site for years, oogling over all the scopes for sale, and just wishing. I got to know fairly well all the ins and outs about scopes in general. But do ya think I would spend a little time reading on eyepieces? Why would I do that?

So now I’m a little perplexed. Here are the questions:

1. a)Where can I go, to a boiled down read of the various eyepieces? There’s nagler 2-6, plossels , hyperion, ethos ( I’ve read a little about ethos, and daddy really likey) etc....
b)And which size 1.25 or 2”

2.I’ve got a grasp on Barlows. I like the Powermates (I know it’s somewhat different from an average Barlow) But should I get 2.5x, 3x, or 4x, in a 2” or 1.25. Logic tells me that the larger diameter of input the more light going through? So is 2” better?

3.Are some eyepieces better for planetary vs DSO?

4.Also my thinking is that eyepieces, for the most part, are engineered to work together better if they are from the same company? EX- A Powermate would probably perform better with a Ethos or nagler, as compare with a Powermate and Baader eyepiece?
Ok that it’s for the long posting. I will keep it shorter the next time. Thank you all, so much, for answering these common newbie tedious letters.

-Terry
P.S. would it be ok to post my scope pictures? When I can get it on the computer?
Posted 09/26/2010 01:37AM #1
Terry swan said:

1. a)Where can I go, to a boiled down read of the various eyepieces? There’s nagler 2-6, plossels , hyperion, ethos ( I’ve read a little about ethos, and daddy really likey) etc....
b)And which size 1.25 or 2�

2.I’ve got a grasp on Barlows. I like the Powermates (I know it’s somewhat different from an average Barlow) But should I get 2.5x, 3x, or 4x, in a 2� or 1.25. Logic tells me that the larger diameter of input the more light going through? So is 2� better?

3.Are some eyepieces better for planetary vs DSO?

4.Also my thinking is that eyepieces, for the most part, are engineered to work together better if they are from the same company? EX- A Powermate would probably perform better with a Ethos or nagler, as compare with a Powermate and Baader eyepiece?
Ok that it’s for the long posting. I will keep it shorter the next time. Thank you all, so much, for answering these common newbie tedious letters.

-Terry
P.S. would it be ok to post my scope pictures? When I can get it on the computer?

1. Ed Ting is worth reading on several eyepiece types: http://www.scopereviews.com/index.html
Excelsis will give you people's reactions to their eyepieces, but not very skilled reviews: http://www.excelsis.com/1.0/section.php?sectionid=22
Cloudy nights of course--the "CN reports" section is usually a little more studied, but not as wide-ranging as the review section: http://www.cloudynights.com/
And of course, here at astromart, there are several good reviews.

Regarding the ethos, there is still an awful lot of hype out there--yes they're fabulous, but so are a lot of other eyepieces with "narrower" but still ample fields. I had a great time with my 13 Ethos, and I wish its new owner lots of joy with it, but I prefer to have a large variety of focal lengths of similar design, so I sold it.

General suggestion: buy used, try it, see if you like it. You'll lose a small amount on the resale--think of this as the price of testing the eyepiece--but you'll take a real bath if you buy new and sell used. If you find a design that appeals to you, plan your collection and work toward it slowly.

You want to move in multiplicative increments in focal length or field, not additive--say you start with a 30mm as the longest fl in your collection: if you divide by 1.4 (~square root 2), you get ~21mm: this fl will have half the field of the 30 (assuming they have the same apparent field, be it 50, 65, or 82 degrees). Then divide by 1.4 again, and you get 15mm. One more time, 11mm, and again, about 8mm. So 30, 21, 15, 11, 8 is roughly a geometric progression, each time cutting the field in half. Add a 2X barlow and the 11 and 8 give you 5.5 and 4, which continues the progression.

2. I don't barlow long fl eyepieces, so I don't see a need for a 2" barlow (but if you want a nice one, check out my antares 1.6X ad smile ). A good 1.25" barlow, like the TV 2x barlow, will serve you in most cases. Some prefer it to the powermates, since it puts fewer elements into the optical path.

3. Yes. But you shouldn't worry about that yet. In an undriven scope like your dob, the T6 naglers will serve you equally well for DSO and planetary in the middle and high mag range. Using a fast scope like yours, you will probably gravitate toward these somewhat expensive but well-corrected widefields.

4. Not necessarily so. OTOH I have almost nothing but televue in my box. I like to play around with good quality plossls for planetary, but they work fine in my TV barlows.

PS Sure, post a picture. We used to have a special forum for that, but try the equipment forum.

good luck!

George Golitzin