Tele Vue 2x Powermate - 2"

The Powermate Concept

Al Nagler's note in the manual explains that Barlow lenses have negative power that diverges field rays; made too short or with too much magnification, they can cause severe vignetting and image degradation from mismatched pupils. His answer was a 4-element parfocal, compact amplifying lens system: a negative achromatic doublet plus a positive "pupil-correcting" doublet.

While it looks and functions like a Barlow, your eyepiece will operate with pupil locations where the designer intended, avoiding mismatch problems, and no additional "interface lens" is needed because Powermates have it built in. Every Powermate goes through Tele Vue's 100% QC program at f/4.

A 2x Factor for High Powers from Long Eye Relief Eyepieces

The 2x Powermate halves the effective focal length of the eyepiece. Tele Vue's own example: with a 22mm Panoptic, you have the power of an 11mm eyepiece. Al Nagler's guide suggests choosing a long focal length eyepiece with comfortable eye relief and using image amplifiers to increase power, and his manual note says Barlows retain eye relief.

The Powermate is fully multi-coated. Planetary and double star observing calls for at least 150x, and the atmosphere usually limits it to about 300x.

Barrel, Filters and Adapter

The 2x Powermate has a 2" barrel, a height of 4.8" (122 mm) and a maximum barrel diameter of 2.7" (68.6 mm). There is a safety undercut on the chrome barrel where practical, and the 2x and 2.5x Powermates do not insert fully on certain diagonals.

• Included Adapter: A 2" to 1¼" eyepiece adapter is in the box, so 1¼" eyepieces fit.
• Filter Compatibility: The spec table lists 48mm filter threads for 2" filters.
• Secure Connection: Tele Vue fits captive lock screws that can't fall out.

Imaging and Coma Correction with T-Rings and Paracorr

Powermates are ideal alternatives to "eyepiece projection" for imaging. For the 2" 2x Powermate, unscrew the chrome barrel, thread it into the special Powermate 2X T-Ring Adapter, and screw that onto your camera's T-Ring adapter.

With Tele Vue's Paracorr in a Newtonian or Dobsonian, insert the 2" Powermate into the telescope's 2" focuser, then insert the Paracorr into the Powermate.

Choosing Your Powermate: The 2x Model vs. the 2.5x, 4x, and 5x

Tele Vue makes Powermates in 1¼" (2.5x and 5x) and 2" (2x and 4x). With a 22mm Panoptic they give 11mm (2x), 8.8mm (2.5x), 5.5mm (4x) and 4.4mm (5x).

• vs. 4x Powermate: Twice the power of the 2x, so it suits shorter telescopes or imaging; in a 2000mm SCT even a 22mm eyepiece reaches 364x, past the usual 300x limit.
• vs. 1.25" Powermates: The 2.5x and 5x take 1¼" eyepieces, are threaded for 1¼" filters, and are parfocal with Tele Vue's 1¼" 90° diagonal. The 2x takes 2" eyepieces, and 1¼" ones with the included adapter.
• Weight Consideration: Heavy 2" eyepieces in the 2x or 4x Powermate could make proper balance difficult on smaller instruments. The 2x weighs 1.20 lbs.