New Price: $380.00 Astromart: $320
Field of view: 50 ° Barrel Size: 1.25" Usable Eye Relief: 10mm
Number of Optical Elements: 5 Weight: 5oz
Unlike all other zooms made, the Nagler zoom maintains a constant and substantial 50 degree apparent field of view at all focal lengths.
Equally important, the usable eye relief stays a constant 10mm. The eyepiece remains parfocal at all focal lengths, as well.
In all other zooms, the apparent field of view and the usable eye relief change as the focal length is changed. Likewise, objects go markedly out of focus as the magnification is changed, as the other zooms are not parfocal. These anomalies don’t happen with the Nagler zoom. The Nagler zoom physically lengthens and contracts as the focal length is changed. This unique approach allows the apparent field, eye relief, and focus to stay the same, no matter what the focal length.
The eyepiece has click stops at 3mm, 4mm, 5mm, and 6mm for quick changes to precise preset magnifications. Naturally, you can use any intermediate focal length between the click-stops, as well. There's a fold-down rubber eyeguard and a rubber grip ring.
The Nagler zoom is designed to provide the best balance of contrast, comfortable eye relief, and resolution for the critical planetary observer. Excellent for those with ultra-premium wide field refractors. It allows the observer to dial in the right balance between magnification, exit pupil, and atmospheric turbulence to achieve the best possible image for the observing conditions at any given moment.
As far as I can tell there have only been a few of these ever listed for sale on Astromart. There seem to be many more want ads. As I have now aquired all the new Nagler Type 6 eyepieces (5,7,9,13 mm) I have duplication of magnification when using a powermate. If you have ever wanted this eyepiece this is a great time to get one at a reduced price. Like new.