Take a "spacewalk" across the widest, sharpest apparent field...
Concept: You may know there's a long history of naming eyepieces after their designers: Kellner, Erfle and Plossl, to name a few. In the late 70's I designed an eyepiece sufficiently radical that I dared attach my name to it. Even today, I must admit a little discomfort when talking about "Nagler" eyepieces.
With "Naglers", my aim is to approach the wide angle perspective of naked eye vision, while maintaining the highest degree of sharpness, contrast, and viewing comfort. The goal is to allow the telescope to virtually "disappear," leaving the impact of "spacewalk" viewing. -Al Nagler
Following are excerpts from the book The Backyard Astronomer by Dickenson & Dyer:
"Al Nagler of Tele Vue caused a sensation when he introduced the Nagler in 1982. The Nagler's success can be attributed to two important innovations: an extremely wide apparent field of 82 degrees with outstanding sharpness and exceptionally comfortable eye relief for eyepieces of very short focal length...He designed his melding of eyepiece and Barlow to operate as a single unit; that is, the aberrations of one cancel out the aberrations of the other, producing exquisitely sharp images edge to edge over an unprecedentedly wide field of view. Nagler's background of optical-systems design for visual flight simulators and his interest in amateur astronomy created the perfect match for this breakthrough."
Compare a penny to a half dollar to see the relative size between a 50 degree and 82 degree apparent field - almost 3 times the area difference! And while others boast of impressive apparent field sizes, Tele Vue's philosophy of "showing no field unless it's fine" stresses full field image quality as the ingredient for impressive views. Blackened lens edges, anti-reflection threads and rubber eyeguards deliver maximum contrast. Adapter skirts for 2" focusers on larger 1.25" models (12mm Nagler Type 4 and 22mm Panoptic) and rubber grip rings are additional Tele Vue "firsts". Even 2"/1¼" barrel models have an additional feature allowing the 2" extension tube (EBX-2120) to be screwed on, which permits use of 2" filters as well as 1¼". 100% full field visual inspection on our own flat-field test instruments guarantees the performance of every Tele Vue eyepiece.
Nagler Type 4
Applying the experience of the Radian development to the 82° Nagler series, yielded more contrast, reduced pincushion, more true field, longer eye-relief, and fewer elements to achieve focal lengths of 12mm, 17mm and 22mm. With added eye-relief, the click-stop Instadjust eyeguard helps maintain proper eye distance and centration.
For deep sky viewing, the comfort, clarity and contrast gets us closer to our “spacewalk” viewing goal.
Nagler Type 5
With the 31mm, the unique 6-element design using four exotic glasses, maintains the contrast advancement of the Type 4s while achieving a true field area 82% larger than the 22mm Type 4! Owners of fast Dobsonian/Newtonians can enjoy a larger true field, free of secondary shadowing, than ever before. For example, a 12.5", f/4.5 scope with a Paracorr will deliver a 1.5 degree field (3 Moon diameters), at 53x with a 6mm exit pupil. Use our eyepiece calculator to figure out what the 31mm will deliver on your scope.
The 16mm Nagler Type 5 is a scaled down version of the "king of the field," 31mm. The new 16mm is a smaller, lighter (0.45 lbs.), 1¼” only, 6-element design which replaces the 8-element 16mm Nagler Type 2. This exciting little high contrast eyepiece looks like a 19mm Panoptic, but packs the visual impact and sharpness we all expect from the 82° Nagler series. This eyepiece offers owners of 1¼" only scopes the largest possible true field in an 82°apparent field eyepiece. Great for small scopes and Bino Vues.
26mm Nagler Type 5: This is a somewhat smaller, lighter and more powerful version of the celebrated 31 Nagler Type 5. Why? Because customers such as Tom Dietz, from the Smithsonian, are pests! :-) It weighs about 1.6 lbs and has a field stop diameter of 35mm. It is parfocal with the 17mm Nagler Type 4, making it a nice match in size, weight and convenience.
The 20mm Type 5 is a compact 1-pound, 2" eyepiece that fills out the eyepiece line and is a worthy successor to the heaviest commercial eyepiece ever produced: the Nagler 20mm Type 2, wich weighed-in at 2.3lb. when introduced in 1986.
Nagler Type 6
The 7-element, Nagler Type 6 design is based on the original patented Nagler design. This new 7-element design update for the short focal length Nagler deserves its own designation. Using different exotic materials, coating processes and design ingenuity, Al has massaged more eye-relief, contrast, and true field of view into the shorter focal length Naglers, while maintaining the absolute sharpness of the originals. Eye-relief is 12mm on each model, and all are sized about the same as the original 7mm! Weight about 0.4 to 0.5 lbs. Available in 13mm, 11mm, 9mm, 7mm, 5mm, 3.5, and 2.5mm focal lengths.
In recognition of the cost increase of the new 7mm and 5mm models over the originals, we intend to continue offering the original 7mm and 4.8mm Naglers. NOTE: The goal we set designing these new eyepieces was to increase contrast, maintain or increase eye-relief, reduce size and weight, and maintain the sharpness of the originals. They are all parfocal and great with the Bino Vue. We are confident we’ve succeeded on all accounts and look forward to your comments.
The 11mm Nagler Type 6 slots in perfectly between the 13mm and 9mm Type 6s and makes a perfect companion to the 7mm.
The 3.5mm Nagler Type 6 is a natural progression of 1.4x power steps from 7mm and 5mm Naglers. The 2.5 is also a 1.4x step from the 3.5mm. You don't have to sacrifice field in order to gain sharpness and power. And, you're not limited to slow scopes, or have to squint through pinhead lenses. These are the lunar and "planetary" eyepieces with field to spare.
User Reports
Despite the presence of no less than seven optical elements, these [Nagler] eyepieces provide images which are noticeably brighter than those obtained with many quality orthoscopics, with superb image sharpness and contrast. Even though these oculars are quite expensive, the serious planetary observer would do well to consider employing this type. — Don Parker et al., Introduction to Observing and Photographing the Solar System, 1988. p. 14
The advantages can be summarized as follows: an 82 degree wide field with unexcelled image sharpness to the extreme edge. This is true even for fast focal ratios; lateral color is very low compared with other widefield eyepieces; the eye relief is very large for a 13mm focal length... . In our view these advantages make this eyepiece one of the most remarkable optical developments for the amateur.
— Martin van Venrooij, Telescope Making Magazine
I also tested their 13mm Nagler Type 6, which yields an exceptional, wide-field, 36x view. The 40x (or so) wide field view is becoming one of my favorite all-purpose views, with enough power for detail and enough field for locating and following birds: the best of both worlds.
— Stephen Ingraham, "Tele Vue Upgrades!", Better View Desired web article, April 2003.
