Eyepiece and telescope pairing
Tele Vue 17.3mm Delos in the Orion SkyQuest XT6 Classic Dobsonian: magnification and field
What the Tele Vue 17.3mm Delos does in the Orion SkyQuest XT6 Classic Dobsonian, worked from the published focal lengths and apparent field.
Field of view
ring = 1.04 degrees true
dot = 2.2 mm exit pupil
- Magnification
- 69x1200 mm / 17.3 mm
- True field
- 1.04 degrees72 deg / 69x
- Exit pupil
- 2.2 mm150 mm / 69x
- Max useful mag
- about 300x2x aperture
Computed optics
- Barrel match
- 1.25 in eyepiece in a 1.25 in focuser
Good fit. In the Orion SkyQuest XT6 Classic Dobsonian the Tele Vue 17.3mm Delos gives 69x with a 1.04 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: 1200 mm divided by 17.3 mm is 69x. The true field of view is the eyepiece's 72 degree apparent field divided by that magnification, 1.04 degrees.
The exit pupil, the width of the light beam leaving the eyepiece, is the aperture divided by the magnification, 150 mm over 69x, which is 2.2 mm. That makes this a medium-power general setting.
The eyepiece to buy
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