Eyepiece and telescope pairing
Tele Vue 11mm Nagler Type 6 in the Orion SkyQuest XT12 Classic Dobsonian: magnification and field
What the Tele Vue 11mm Nagler Type 6 does in the Orion SkyQuest XT12 Classic Dobsonian, worked from the published focal lengths and apparent field.
Field of view
ring = 0.6 degrees true
dot = 2.2 mm exit pupil
- Magnification
- 136x1500 mm / 11 mm
- True field
- 0.6 degrees82 deg / 136x
- Exit pupil
- 2.2 mm305 mm / 136x
- Max useful mag
- about 610x2x aperture
Computed optics
- Barrel match
- 1.25 in eyepiece in a 2 in focuser
Good fit. In the Orion SkyQuest XT12 Classic Dobsonian the Tele Vue 11mm Nagler Type 6 gives 136x with a 0.6 degree true field and a 2.2 mm exit pupil, inside the telescope's useful range.
Magnification is the telescope focal length divided by the eyepiece focal length: 1500 mm divided by 11 mm is 136x. The true field of view is the eyepiece's 82 degree apparent field divided by that magnification, 0.6 degrees.
The exit pupil, the width of the light beam leaving the eyepiece, is the aperture divided by the magnification, 305 mm over 136x, which is 2.2 mm. That makes this a medium-power general setting.
The eyepiece to buy
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