82° Apparent Field Eyepieces
|TeleVue.com: Eyepieces > Nagler > 20mm|
|Focal Length (mm)||20|
|Barrel Size (in.)||2"|
|Apparent Field of View (deg.)||82|
|Eye Relief (mm)||12|
|Weight (lb / oz)||1.04 / 16.6|
|Field Stop (mm)||27.4|
|Compare to similar focal lengths|
The 20mm Type 5 is a compact 1-pound, 2" eyepiece that fills out the eyepiece line and is a worthy successor to the heaviest commercial eyepiece ever produced: the Nagler 20mm Type 2, which weighed-in at 2.3-lb. when introduced in 1986.
To achieve the full magnification range over 82° apparent field of view requires two types: Nagler Type-5 with focal lengths of 31, 26, 20, 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), while the shorter focal length Type-6 models are parfocal, with similiar size and weight and all with a comfortable 12mm eye relief.