Tele Vue 31mm Nagler Type 5 Eyepiece - 2

$665.01
Article number: EN5-31.0
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Delivery time: Ships in 2-3 business days from our Warehouse
31-mm
Model # EN5-31.0
Focal Length (mm) 31
Barrel Size (in.) 2"
Apparent Field of View (deg.) 82
Eye Relief (mm) 19
Weight (lb / oz) 2.20 / 35.2
Field Stop (mm) 42
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With the 31mm, the unique 6-element design using four exotic glasses, maintains the contrast advancement of the Type 4s while achieving a true field area 82% larger than the 22mm Type 4! Owners of fast Dobsonian/Newtonians can enjoy a larger true field, free of secondary shadowing, than ever before. For example, a 12.5", f/4.5 scope with a Paracorr will deliver a 1.5 degree field (3 Moon diameters), at 53x with a 6mm exit pupil. Use our eyepiece calculator to figure out what the 31mm will deliver on your scope.

Why Are There 3 Types of Naglers?

To achieve the full magnification range over 82° apparent field of view requires two types: Nagler Type-5 with focal lengths of 31, 16mm and Nagler Type-6 with focal lengths of 13, 11, 9, 7, 5, 3.5, 2.5mm.

The Type-5 permits the largest true field possible (31mm has 42mm field stop).

Type-6 models have shorter focal lengths, are parfocal, with similiar size and weight, and all with a comfortable 12mm eye relief.

The Type-4 models feature about 18mm of eye relief and with the "instajust" eyeguard are best for eyeglass wearers or Dioptrx users in their 22, 17, 12mm focal length range.

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