Tele Vue 1.25" Nagler Planetary Zoom Eyepiece 2-4mm

Our Price: $415.00
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Out of Stock
Availability: Item has been discontinued and is no longer available.
Our Product ID: ZZE-ZZTV-NAGZOOM2-4
Manufacturer SKU: ENZ-0204
Item Can Ship: Worldwide
Tele Vue 1.25" Nagler Planetary Zoom Eyepiece 2-4mm

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Availability: Item has been discontinued and is no longer available.

Product Details

The 2-4mm Nagler Zoom is recommended for fast, high performance scopes of 800mm focal length or shorter, such as the Tele Vue-60. It has click-stops every half-mm.

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

Manufacturer Tele Vue
Eyepiece Series Nagler
Focal Length 2-4mm
Barrel Size 1.25" (31.7mm)
Apparent Field of View (Mfg Specified) 50°
Eye Relief (Designed) 10mm
Filter Threads Standard 1.25" Filter Thread (M28.5 x 0.6)
Coatings Fully Multi-Coated
Lens Elements 5
Lens Groups 3
Blackened Lens Edges Yes
Barrel Safety Recess Yes
Barrel Type With safety undercut
Protective Plastic Storage Container Discontinued Item
Protective Plastic Storage Container Size Agena 42x60mm
Optical Design Nagler
Maximum Width 1.7" (43.2mm)
Field Stop Diameter 1.7mm - 3.3mm
Parfocal Yes
Rubber Eye Guard Yes
Warranty Limited lifetime warranty
Weight 5.7 oz

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