While Barlows are powerful tools, the negative element defining them also limits their ability. The simple negative element Barlow increases eyepiece eye-relief. With short focal length eyepieces the effect is negligible. However, on long focal length eyepieces the exit pupil position moves well beyond the designer's intended position, resulting in vignetting with many eyepieces. This is why "Shorty" Barlows in particular, with their strong negative element often vignette and degrade long focus eyepieces. My 4-element form picks up where the Barlow concept can go no further. Powermate™ is a technically universal solution, using a positive field lens to redirect field rays. The result is an exit pupil that stays where the eyepiece designer intended. With freedom from aberrations, greater magnification potential, and compact size, I hope you'll agree Powermate™ raises the standard for image amplification. — Al Nagler

Al Nagler's 4-element concept, continues the tradition of full-field sharpness with optimum aberration control. Like long eye-relief? Retain the eye-relief of long focal length eyepieces, while at high power. Enjoy, for example, the sharpness and comfort of the 32mm Plössl at up to 5 times the power!

2" Powermates™: 2x

These Powermates™ are a better choice for 2" diagonals than Barlows, since they are nearly Parfocal. They are threaded for 48mm filters and their performance is excellent with every 1¼" and 2" eyepiece we make (yes, even the 31mm Nagler Type 5!). Both the 2" eyepiece holder and the special 2" flat top adapter use our brass clamp rings for secure operation. And, it also has a very unique feature: you can unscrew the 2" eyepiece housing and screw on a special T-ring adapter for solid, compact attachment of CCD or camera equipment.

Excellent with long eye-relief, 2" eyepieces. The Powermate™ is NOT a Barlow so the Panoptic-Barlow Interface is not needed! The 2" Powermate™ fits all the way into 2" Star Diagonals, requiring minimal refocus compared to a 2" Barlow. Weight is approx. 545 gram.

Note for Dobsonian/Newtonian Owners

When using Tele Vue's Paracorr coma corrector, For 2x 2" Powermates™, first insert the Powermate™ into the focuser, then the Paracorr into the Powermates™.

Benefits and Applications for Powermates™

1. Vignetting, edge field aberrations and pupil movement - all introduced when using Barlows with long focal length eyepieces, are minimized.
2. Telecentric operation (field rays leave parallel to optical axis, unlike Barlow lenses which diverge rays). This is ideal for Hydrogen-alpha filter use such as with Daystar models.
3. High performance for image amplification, CCD or film (some of the finest Earth-based planetary imaging is being done with Powermates™.
4. Flexible for visual and imaging with all types of telescopes and eyepieces. Essentially Parfocal, and with nearly constant magnification regardless of image distance behind top surface (except 5x model which increases 1x for every 35mm of image distance increase).
5. Higher magnifications are possible with high optical performance compared to "doubling up" Barlows.
6. All will reach parfocal point in star diagonals, except for the 2", 2x which comes very close.

In addition to full multi-coating, Powermates™ include other Tele Vue special touches such as safety undercuts where practical on the chrome barrel and captive lock screws that can't fall out, and filter threads. Our 100% QC program at f/4 insures that Powermates™ will add dramatic power (and NOTHING ELSE) to your favorite eyepieces.