Eyepiece and telescope pairing
Celestron X-Cel LX 2.3mm in the Orion SkyQuest XT12 Classic Dobsonian: magnification and field
What the Celestron X-Cel LX 2.3mm does in the Orion SkyQuest XT12 Classic Dobsonian, worked from the published focal lengths and apparent field.
Field of view
ring = 0.09 degrees true
dot = 0.5 mm exit pupil
- Magnification
- 652x1500 mm / 2.3 mm
- True field
- 0.09 degrees60 deg / 652x
- Exit pupil
- 0.5 mm305 mm / 652x
- Max useful mag
- about 610x2x aperture
Computed optics
- Barrel match
- 1.25 in eyepiece in a 2 in focuser
Over-powered. At 652x this pair exceeds the highest useful magnification of about 610x for the Orion SkyQuest XT12 Classic Dobsonian, so the image dims and softens without showing more real detail. Use a longer eyepiece.
Magnification is the telescope focal length divided by the eyepiece focal length: 1500 mm divided by 2.3 mm is 652x. The true field of view is the eyepiece's 60 degree apparent field divided by that magnification, 0.09 degrees.
The exit pupil, the width of the light beam leaving the eyepiece, is the aperture divided by the magnification, 305 mm over 652x, which is 0.5 mm. That makes this a high-power lunar, planetary and double-star setting.
The eyepiece to buy
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