Eyepiece and telescope pairing
Celestron Omni 9mm Plossl in the Sky-Watcher Heritage 130P: magnification and field
What the Celestron Omni 9mm Plossl does in the Sky-Watcher Heritage 130P, worked from the published focal lengths and apparent field.
Field of view
ring = 0.69 degrees true
dot = 1.8 mm exit pupil
- Magnification
- 72x650 mm / 9 mm
- True field
- 0.69 degrees50 deg / 72x
- Exit pupil
- 1.8 mm130 mm / 72x
- Max useful mag
- about 260x2x aperture
Computed optics
- Barrel match
- 1.25 in eyepiece in a 1.25 in focuser
Good fit. In the Sky-Watcher Heritage 130P the Celestron Omni 9mm Plossl gives 72x with a 0.69 degree true field and a 1.8 mm exit pupil, inside the telescope's useful range.
Magnification is the telescope focal length divided by the eyepiece focal length: 650 mm divided by 9 mm is 72x. The true field of view is the eyepiece's 50 degree apparent field divided by that magnification, 0.69 degrees.
The exit pupil, the width of the light beam leaving the eyepiece, is the aperture divided by the magnification, 130 mm over 72x, which is 1.8 mm. That makes this a medium-power general setting.
The eyepiece to buy
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