The 3-6mm Nagler Zoom is an exceptional, specialized high-power eyepiece for dialing in the optimum power for planetary viewing with short-focal-length telescopes, such as fast apo refractors. Imaging is superb, and the apparent field stays constant throughout the zoom range. Click stops define the 6mm, 5mm, 4mm and 3mm positions. It also lets observers choose in-between focal lengths, thus giving them the ability to tune the magnification to atmospheric conditions, which is very critical for high-power viewing.
Concept / Background: I did not set out to design a zoom eyepiece, per se. David and I were discussing characteristics we'd like in a superior "planetary" eyepiece, and the zoom feature answered one of the major goals; how to obtain the highest possible useful magnification on a given night considering the ever-changing atmosphere. There were other aspects of equal importance and only the combination of all would satisfy our ethos in creating a "planetary" eyepiece: full field sharpness for any speed telescope, high contrast and transmission for natural color rendition, low scatter, and comfortable eye-relief. Being a zoom, we also concerned ourselves with making sure it was parfocal through the zoom range as well maintaining a constant apparent field of view. The one aspect we were not too concerned with was giving the eyepiece a wide AFOV.
Limiting the AFOV to 50° and the eye-relief to 10mm, we were able to create a compact physical design employing only five elements to reach the optical goals. Like other "Naglers," it utilized a negative lens group ahead of the focal plane. This permitted relatively long eye-relief for very short focal lengths. By independently moving the upper and lower lens groups, we achieved constant focus (parfocality), constant apparent field of view, and essentially constant eye-relief. Just by rotating the upper barrel, you can zoom through the power range. Click stops offer known power points for reference without needing to look at the barrel and instantaneously choose the optimum magnification for the given observing conditions.
I was sufficiently confident in the design and purposely decided to attach my name to the zoom, despite the common association between "Nagler" and 82° AFOV. I felt it was more important to stake our reputation on overcoming the "degrading zoom reputation" than maintaining the 82° assumption for "Nagler" designs.— Al Nagler
Jul 2, 2018
best eyepiece yetPros: Cons: Comments:
I needed some small focal length premium eyepieces for my small refractors.
It would just cost too much to have 4 or 5 of these.
This short focal length zoom eyepiece was the answer to my problem.
I basically have 4 eyepieces in one with the same field of view now.
This review was provided courtesy of AgenaAstro.comDec 10, 2013
The best eyepiece that you can buy.Pros:
Because to tell you, the best eye that I have. With the Newton 200/1000A current probe the problem with our little focal is get increases for planets, and at the time I also doubted that focal choose and the opportunity arose to acquire the zoom of 3-6, and hear a joy, I have all the needed increases for every occasion and above without go changing eyepiece. My conclusion is that it is an excellent eyepiece.
This review was provided courtesy of AgenaAstro.com
kevinbozard New Member
- Skill Level
- Time with Product
Mar 18, 2008
- User Notes:
A powerful eyepiece, in more ways than one!Pros:
Premium optics, parfocal, easy to useCons:
I had the opportunity of field testing this eyepiece during a presentation by Nagler. I was also one of those amateurs that thought a zoom eyepiece was a waste of money. After setting up a Tele Vue 85, Mr. Nagler showed off his wares with a standard plossl in place. After the crowd had thinned, he dropped in the 3mm-6mm zoom. Out of curiosity, I made my way to the scope and gave the zoom piece a run. The eyepiece as it turns out, was outstanding. Of course, using a nice eyepiece in a very nice scope may have helped too. Image quality was amazing, and the clarity was second to none. One feature I loved was the fact that the eyepiece was parfocal, which means I didn't have to refocus each time I changed the setting. That alone makes the eyepiece worth it's weight in cost. Also, the different settings could be achieved without removing the eyepiece from it's holder, which was another big plus. I have to save some cash, but as soon as I reach my goal, one of these babies will be residing in my equipment case.
astroman7 New Member
- Skill Level
- Time with Product
Jan 16, 2007
- User Notes:
A Zoom Worth OwningPros:
Great power range for planetsCons:
None discovered yetComments:
I used to think "who would want to spend this much money on a zoom that covers only 4mm in range". With that mentality, I bought a cheap 7-21mm zoom which I promptly resold. I found myself much preferring the set size eyepieces in that power range due to the wider FOV etc. Anyway, with the goal to own too many eyepieces, I bought the Televue 3-6 zoom just to try it out. Conclusion... this is one zoom eyepiece worth having. It is well made and carries with it the quality typical of Televue goods. At over $300, it is pricey, especially for an 1.25" eyepiece, but will save you from owning multiple EP's in that power range. Although a bit powerful for my Nexstar 11, it has a great power range for my Nexstar 5 and especially my 102 refractor. I love the "way" that it zooms where a silky smooth twist brings you to a click stop at 3, 4, 5, & 6mm respectively. Unlike with deep sky objects, in viewing planets, most of us typically want the highest power that any given night will allow. Thus owning a zoom in this range allows you to easily discover the power limits of the particular viewing session. You will find yourself using this one more than anticipated. I do not use Barlows all that much either, but put a Barlow on this one and you have a really powerful eyepiece for really pushing the limits of your smaller scopes. Highly recommended!Sort by
Apparent Field of View 50° Barrel Size 1.25" (31.7mm) Bolt Case Included Yes - Free Agena Eyepiece Container Bolt Case Size Agena 42x60mm Coatings Fully Multi-Coated Design Nagler Max Width 1.7" (43.2mm) Eye Relief by Design 10mm Field Stop Diameter 2.6mm - 5.1mm Filter Threads Standard 1.25" Filter Thread (M28.5 x 0.6) Focal Length 3mm Lens Elements 5 Lens Groups 3 Parfocal Yes Rubber Eye Guard Yes Blackened Lens Edges Yes Additional Information
- Suitable for use with Tele Vue Bino Vue binoviewer
- Not suitable for use with Tele Vue Dioptrx / digiscoping
Manufacturer TeleVue Eyepiece Focal Length Variable Range Eyepiece Field of View 51 - 60 degrees Eyepiece Series Tele Vue Nagler Barrel Type With safety undercut Eyepiece Weight 5.30oz (150.25g)