Powermates are the highly-evolved answer to the Barlow lens design from Tele Vue.
While barlow lenses increase the eye relief of the eyepiece in use, they also reposition the exit pupil of long focal length eyepieces far from the designer's intended position. This can cause vignetting and image degradation.
Using four elements, the Powermates leave the exit pupil where it was intended to be, restoring the full viewing aperture and optical quality of long focal length eyepieces. Have the best of both worlds; the long eye relief of the longer focal length eyepieces, but with higher magnification!
This Powermate is parfocal in all 1.25" diagonals & prisms, and is thus highly recommended over standard barlow lenses for refractors with 1.25" focusers.
Directly accepts all 1.25" eyepiece
Works well with diagonals, unlike many normal Barlow lenses
Accepts optional PTR-1250 SLR camera adapter (imaging w/o eyepiece)
 
 
Vignetting, edge field aberrations and pupil movement - all introduced when using Barlows with long focal length eyepieces, are minimised.
4-element optical design
Brass compression ring to protect your eyepieces from marring
Proprietary tuned full multi-coatings & high index glass
Blackened lens edges & Anti-reflective thread
Eyepiece adapter is removeable to allow optional t-ring adapter to be fitted
Captive lock screws that can't fall out
Threaded for 1.25" filters
Safety undercut in nosepiece barrel for extra locking security
100% QC program at f/4 insures that Powermates™ will add dramatic power (and NOTHING ELSE) to your favorite eyepieces.