Good "conversation" on eye pieces here. Chuck, you're comments are very informative and helpful (to everyone). This is the real value of this board - the exchange of information and knowledge (about astronomy). As Siegfried well knows :) I have a 6" Brandt doublet refractor, fl 16.3. Incredibly long (the tube alone is 8 feet in length -yikes, ugh, n ah, very light weight actually - it's just the climbing up the ladder steps with it and lifiting it over the head to seat it in the cradle (but worth it :)) ) MANY years ago, at Siegfried's suggestion, encouragement, recommendation ... two Clave eyepieces were purchased and they are still the best eyepieces to use in that refractor. Also, many years ago, the Clave's were put into a dobsonian and the views, while good were easily beat by other eyepieces. Chuck's comments explain why. Still, I would NEVER give or sell those clave s . Eyepieces are like telescopes, a good scope or (eyepiece) will not "wear out" or lose it's abillity to provide mind numbing views. Well, you might get aperturitis , but it's a disease only the ardent astronomer can appreciate. The best eye piece for a scope depends on the scope. It doesn't have to cost an arm and a leg, it just had to work with your optical system.
On Thu, Jan 26, 2012 at 12:25 PM, <jcarman6@q.com> wrote:
It doesn't have to cost an arm and a leg, it just had to work with your optical system.
That's a big reason I make many of my own eyepieces. (Plus, it's fun, and not a lot of amateurs did it prior to about ten years ago). Back around the turn of the century, in the heyday of the refractor, the eyepiece of choice was a negative lens in most instances. FOV's were incredibly narrow, but then the primary work of astronomers was mostly positional work, and spectroscopy. The beginnings of modern astro-physics. Here's a web page that gives brief descriptions and histories for many familiar designs, including the monocentric: http://www.chuckhawks.com/common_eyepiece_designs.htm
Chuck, have you made a Nagler?
On Thu, Jan 26, 2012 at 12:25 PM, <jcarman6@q.com> wrote:
It doesn't have to cost an arm and a leg, it just had to work with your optical system.
That's a big reason I make many of my own eyepieces. (Plus, it's fun, and not a lot of amateurs did it prior to about ten years ago).
Back around the turn of the century, in the heyday of the refractor, the eyepiece of choice was a negative lens in most instances. FOV's were incredibly narrow, but then the primary work of astronomers was mostly positional work, and spectroscopy. The beginnings of modern astro-physics.
Here's a web page that gives brief descriptions and histories for many familiar designs, including the monocentric:
http://www.chuckhawks.com/common_eyepiece_designs.htm _______________________________________________ Utah-Astronomy mailing list http://mailman.xmission.com/cgi-bin/mailman/listinfo/utah-astronomy
Send messages to the list to Utah-Astronomy@mailman.xmission.com
The Utah-Astronomy mailing list is not affiliated with any astronomy club.
To unsubscribe go to: http://mailman.xmission.com/cgi-bin/mailman/listinfo/utah-astronomy Then enter your email address in the space provided and click on "Unsubscribe or edit options".
On Fri, Jan 27, 2012 at 9:56 AM, <erikhansen@thebluezone.net> wrote:
Chuck, have you made a Nagler?
No, no modern "exotic" designs. I don't grind my own eyepiece lenses (yet) so I'm limited to what's available in the surplus market. You don't see surplus Asian-manufacture eyepiece lenses showing up at Surplus Shed. I'm sure Al Nagler contractually demands that "seconds" be destroyed, anyway. Modern, ultra-wide-field designs have departed from traditional eyepiece formulae thanks to new glass formulations and computer-aided design. The amateur certainly could produce such an eyepiece, but it probably wouldn't be cost-effective given the investment in time and procurement of the glass needed. Those designs that use aspherical lenses are even more problematic. Traditional refractive optics use spherical surfaces almost exclusively. Much easier to polish and figure. Spherical lens surfaces are are manufactured by machine, from beginning to end. Aspherical surfaces need the human touch to figure. You have to remember that Plossls, symmetricals, Konigs, Kellners, and Erfles are all really variations on a theme. There is no hard-and-fast rule that defines them (except the symmetrical design, of course). I've managed to sneak-up on about a 65-degree AFOV with my home-brew stuff, before edge aberrations become objectionable or the field gets objectionably curved. Beyond that, you're into Nagler territory and out of the land of the bottom-feeders. ;-) If you're wondering why modern eyepieces such as Naglers cost about as much as a good-quality camera lens, it's because, essentially, they have as much or more glass in them, with similar curves, as good-quality camera lenses. In fact, when you take into account that there are a lot fewer eyepieces sold than camera lenses, the costs become a lot more reasonable. Trivia: The basic Nagler wide-field design came from Al Nagler's working with the Apollo space program imaging team.
participants (3)
-
Chuck Hards -
erikhansen＠thebluezone.net -
jcarman6＠q.com