Chuck, When I get a chance I will compare the Nagler to my 13 mm Plossl, unfortunately I don't have any Orthos in that focal length. -----Original Message----- From: utah-astronomy-bounces@mailman.xmission.com [mailto:utah-astronomy-bounces@mailman.xmission.com] On Behalf Of Chuck Hards Sent: Thursday, July 30, 2009 11:04 AM To: Utah Astronomy Subject: Re: [Utah-astronomy] Jupiter Impact Scar Good report, Don, thanks. If you have a good orthoscopic, I'd be interested in your impressions of resolution when compared to the Nagler. Dick Suiter, in his book "Star Testing Astronomical Telescopes", demonstrated with spot diagrams that the Naglers are a tad soft in the center. I'm at work now so I can't cite the chapter and page. Those simulations were probably done using the original Nagler design; it's been years now since the book was published. But my own admittedly infrequent comparisons bore that out. The FOV of the orthos was only half that of the Nagler, but I always felt I could see finer detail with the Abbe Ortho than the Nagler, stated ep focal lengths never differing by no more than a mm. I also wondered why Tele Vue would sell a different line of eyepieces (Panoptics, IIRC) as "Tack Sharp", but of narrower FOV than the Nagler, if the Naglers were diffraction limited- which Suiter claims they're not. On Thu, Jul 30, 2009 at 10:46 AM, Don J. Colton <djcolton@piol.com> wrote:
I started observing Jupiter's impact scar about 3:45 AM and ended at 4:10 AM (July 30, MDT). I was using an 8" Celestron Ultima SCT at 160x and 236X. At first the scar was faint and barely visible at 160X. Seeing improved markedly after a few minutes and the scar was easily visible. I watched it transit approximately as scheduled (I didn't try to time it). I was surprised how visible it was compared to the last time, but then I was using a smaller scope under poorer seeing. I assume it is now harder to see, all things being equal, than it was on July 23.
I noticed a fairly significant improvement in detail when I switched from a 1.25" - 13 mm Meade Super Wide to a 1.25" - 13mm Nagler Type 6. Even though the Nagler had more glass the image was clearly sharper and the scar more readily observed. The Nagler was probably superior due to better optics and coatings. Previously I had not considered Naglers' to be planetary eyepieces.
_______________________________________________ Utah-Astronomy mailing list Utah-Astronomy@mailman.xmission.com http://mailman.xmission.com/cgi-bin/mailman/listinfo/utah-astronomy Visit the Photo Gallery: http://www.slas.us/gallery2/main.php Visit the Wiki: http://www.utahastronomy.com