liss@psyche.DEC (Frederick R. Liss 237-3649) (06/04/85)
After a long hiatus I am getting back into astronomy. Sky And Telescope magazine is completely different from what it was back in the late 50s and early 60s. Believe it or not, the most confusing thing that I find today is the advertisements for telescope eyepieces. When I got my first telescope there were only a few types of eyepieces. I'm not sure of the spelling or the exact names, but I believe they were the Orthoscopic (?) and Hyugens (?) eyepieces (correct me if I'm wrong) . Today I see adds for Nagler, Wide Field, Plossl, and Kelner eyepieces. What I would like to know is how do all these eyepieces compare in price and performance. Which ones are suitable for high or low magnification, field of view, etc. I have also heard that some eyepieces work better with a refractor than with a reflector. What is your personal preference? My applications are observation of the Moon as well as the brighter clusters and nebulas. Regards, Fred --- Frederick R. Liss UUCP ...decvax!decwrl!dec-rhea!dec-psyche!liss Digital Equipment Corp. ARPA liss%psyche.DEC@decwrl.ARPA 333 South St. Shrewsbury MA, 01545 Mail Stop SHR1-4/D21 Posted: Tue 4-Jun-1985 09:35 To: RHEA::DECWRL::"net.astro.expert"
freeman@spar.UUCP (Jay Freeman) (06/04/85)
In article <2470@decwrl.UUCP> liss@psyche.DEC (Frederick R. Liss 237-3649) writes: > ... types of eyepieces. I'm not sure of the >spelling or the exact names, but I believe they were the Orthoscopic (?) >and Hyugens (?) eyepieces (correct me if I'm wrong) . Today I see adds >for Nagler, Wide Field, Plossl, and Kelner eyepieces. > >What I would like to know is how do all these eyepieces compare in price >and performance. Which ones are suitable for high or low magnification, >field of view, etc. I have also heard that some eyepieces work better >with a refractor than with a reflector. What is your personal >preference? My applications are observation of the Moon as well as the >brighter clusters and nebulas. I am an amateur astronomer with moderate experience with deep-sky observing (approximately 2500 different objects logged). Most of my observing is with a Celestron 14 (14-inch aperture Schmidt-Cassegrain, f/11), most of the rest with six- and eight-inch f/5 Newtonians. For deep-sky observing with the C-14 my favorite eyepieces, in order from most-commonly used to least-commonly used, are 55 mm Plossl (71X, University Optics, 2-inch barrel) 12.4 mm Erfle (315X, Meade) 32 mm Erfle (122X, University Optics, 2-inch barrel) 20 mm Erfle (196X, Meade) I use a low power for finding things and general viewing -- 71X is very nearly a rich-field power on the big Celestron -- then occasionally switch to more magnification to see detail, resolve stars, or cope with unusual contrasts. I have infrequently used 7mm and 4mm Orthoscopics to advantage with this instrument, on close double stars. I have sampled a variety of other eyepieces with this instrument in each of these power ranges. I advocate these more expensive eyepieces over cheaper ones (Orthoscopics, Kellners, ...) because of wider apparant fields of view and freedom from internal reflections. Image quality is not too much an issue at f/11, except at the very edges of the field. Even an inexpensive coated Ramsden half-inch eyepiece (Jaegers) gave superb definition near the center of its narrow field, and was in that respect indistinguishable from the most expensive half-inch eyepieces. (Actually, it may have been slightly superior, because of fewer air-glass interfaces.) I personally have little use for the very-wide-field eyepieces such as the 82-degree apparant-field Naglers: I find views through them momentarily spectacular, but have difficulty keeping my eye sufficiently precisely located to avoid obstructing portions of the field by parts of my own pupil. With the f/5 Newtonians, my favorite eyepiece for deep-sky work is the Meade 20mm Erfle mentioned above, closely followed by the best 4mm or 6mm Orthoscopic I can get my hands on. At f/5, image quality is everything! You need the best eyepieces you can find (read "expensive") to work with a fast Newtonian. NB: Occasionally a specific Kellner will work well with a specific Newtonian -- the 25mm Kellners that Coulter ships with some of their Dobsons are often satisfactory. I have never seen a Barlow lens that was good for much at f/5. Some of them work pretty well at longer f numbers, but there you don't usually need them since there are plenty of short-focal-length eyepieces that will do just as well. I have no financial interest, and no axes to grind, with any of the companies mentioned. -- Jay Reynolds Freeman (Schlumberger Palo Alto Research)(canonical disclaimer)
chris@leadsv.UUCP (06/06/85)
In article <2470@decwrl.UUCP>, liss@psyche.DEC (Frederick R. Liss 237-3649) writes: > today is the advertisements for telescope eyepieces. When I got my first > telescope there were only a few types of eyepieces. I'm not sure of the > spelling or the exact names, but I believe they were the Orthoscopic (?) > and Hyugens (?) eyepieces (correct me if I'm wrong) . Today I see adds > for Nagler, Wide Field, Plossl, and Kelner eyepieces. What you are seeing is a variation in the complexity of the construction of the lenses. The cheapest lenses (such as Huygens) are made with one or two simple lens. Orthoscopic, an expensive brand, is made of several lenses packed together. The newer lenses fill in the gap in between. The reasons for different lenses are several: 1. To offer the customer a variety of price ranges. 2. To offer different degrees of solution to the various problems associated with lenses. One problem is chromatism, or the tendency for the lense to act like a prism and break up the light of the image, particularly near the edges. Some types of lenses are limited in their focusing power. All the brands should come in a variety of magnifications and allow the option for a filter to be installed in the base of the eyepiece. Some lenses are better built (shock proof, etc.) but cost more. As far as lenses being matched to a particular type of telescope, I believe that eyepieces with wider fields are best used with shorter focal lengths. There is a maximum practical eyepiece magnification for a given telescope. The manual that comes with it should mention this. (E.g., a 60mm refractor shouldn't be used with anything smaller than a 12.5 mm eyepiece. ) An excellent source for information on telescopes is Edmund Scientific Co. in New Jersey. They sell everything associated with the hobby through a mail order catalog that they put out. - Christopher Salander Lockheed Space Systems Div. Silicon Valley
GMS@psuvm.BITNET (06/07/85)
My personal eyepiece preference is a wide-angle Erfle (28 millimeters)
that (believe it or not) is (or was) manufactured by Edmund Scientific.
I use it with a mead 8" F6 reflector and get excellent wide-field views
(almost 1 degree field) of deep-sky objects. The only object it is not
ideal for is small planetary nebula of under 1 arcminute in diameter.
For clusters, diffuse nebulae and galaxies it is great! I have reached
13.5 magnitude (under excellent conditions) with certainty (ie no
averted vision).
It is also great for variable star work, with a field large enough for
comparison stars and makes 'star-hopping' location techniques good also.
Gerry Santoro . . . !psuvax1!santoro
Penn State University . . . !psuvax1!psuvm.bitnet!gms
"I may not know whats best but I know what I like!"
tae@rayssd.UUCP (Thomas A. Edler) (06/14/85)
=== REFERENCED ARTICLE =================================== > Relay-Version: version B 2.10 5/3/83; site rayssd.UUCP > Posting-Version: Version 1.0 Netnews CMS/BITNET 5/19/85; site PSUVM.BITNET > Path: rayssd!raybed2!linus!philabs!cmcl2!seismo!rochester!cmu-cs-pt!cadre!psuvax1!psuvm.bitnet!gms > From: GMS@psuvm.BITNET > Newsgroups: net.astro.expert > Subject: Re: Eyepieces > Message-ID: <1829GMS@psuvm> > Date: Thu, 6-Jun-85 23:16:13 EDT > Article-I.D.: psuvm.1829GMS > Posted: Thu Jun 6 23:16:13 1985 > Date-Received: Fri, 14-Jun-85 03:14:09 EDT > References: <2470@decwrl.UUCP> > Lines: 19 > > My personal eyepiece preference is a wide-angle Erfle (28 millimeters) > that (believe it or not) is (or was) manufactured by Edmund Scientific. > > I use it with a mead 8" F6 reflector and get excellent wide-field views > (almost 1 degree field) of deep-sky objects. The only object it is not > ideal for is small planetary nebula of under 1 arcminute in diameter. > For clusters, diffuse nebulae and galaxies it is great! I have reached > 13.5 magnitude (under excellent conditions) with certainty (ie no > averted vision). > > It is also great for variable star work, with a field large enough for > comparison stars and makes 'star-hopping' location techniques good also. > > Gerry Santoro . . . !psuvax1!santoro > Penn State University . . . !psuvax1!psuvm.bitnet!gms > > > "I may not know whats best but I know what I like!" > ========================================================== *** REPLACE THIS LINE WITH YOUR MESSAGE ***
tae@rayssd.UUCP (Thomas A. Edler) (06/14/85)
*to who it may concern.
readnews@rayssd.UUCP (USENET Current Events) (06/19/85)
*an interesting opinion!