Televue Nagler 82-deg FOV Eyepiece - 31mm
|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|
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.
To achieve the full magnification range over 82° apparent field of view requires two types: Nagler Type-5 with focal lengths of 31 mm and 16 mm and Nagler Type-6 with focal lengths of 13 mm, 11 mm, 9 mm, 7 mm, 5 mm, 3.5 mm, 2.5 mm
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 mm, 17 mm and 12 mm focal length range.