Eyepiece and telescope pairing
Tele Vue 11mm Nagler Type 6 in the Orion SkyQuest XT4.5 Classic Dobsonian: magnification and field
What the Tele Vue 11mm Nagler Type 6 does in the Orion SkyQuest XT4.5 Classic Dobsonian, worked from the published focal lengths and apparent field.
Field of view
ring = 1 degrees true
dot = 1.4 mm exit pupil
- Magnification
- 82x900 mm / 11 mm
- True field
- 1 degrees82 deg / 82x
- Exit pupil
- 1.4 mm114 mm / 82x
- Max useful mag
- about 228x2x aperture
Computed optics
- Barrel match
- 1.25 in eyepiece in a 1.25 in focuser
Good fit. In the Orion SkyQuest XT4.5 Classic Dobsonian the Tele Vue 11mm Nagler Type 6 gives 82x with a 1 degree true field and a 1.4 mm exit pupil, inside the telescope's useful range.
Magnification is the telescope focal length divided by the eyepiece focal length: 900 mm divided by 11 mm is 82x. The true field of view is the eyepiece's 82 degree apparent field divided by that magnification, 1 degrees.
The exit pupil, the width of the light beam leaving the eyepiece, is the aperture divided by the magnification, 114 mm over 82x, which is 1.4 mm. That makes this a high-power lunar, planetary and double-star setting.
The eyepiece to buy
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