Eyepiece and telescope pairing
Celestron Omni 40mm Plossl in the Celestron C14 optical tube: magnification and field
What the Celestron Omni 40mm Plossl does in the Celestron C14 optical tube, worked from the published focal lengths and apparent field.
Field of view
ring = 0.41 degrees true
dot = 3.6 mm exit pupil
- Magnification
- 98x3910 mm / 40 mm
- True field
- 0.41 degrees40 deg / 98x
- Exit pupil
- 3.6 mm356 mm / 98x
- Max useful mag
- 840xpublished
Computed optics
- Barrel match
- 1.25 in eyepiece in a 2 in focuser
Good fit. In the Celestron C14 optical tube the Celestron Omni 40mm Plossl gives 98x with a 0.41 degree true field and a 3.6 mm exit pupil, inside the telescope's useful range.
Magnification is the telescope focal length divided by the eyepiece focal length: 3910 mm divided by 40 mm is 98x. The true field of view is the eyepiece's 40 degree apparent field divided by that magnification, 0.41 degrees.
The exit pupil, the width of the light beam leaving the eyepiece, is the aperture divided by the magnification, 356 mm over 98x, which is 3.6 mm. That makes this a medium-power general setting.
The eyepiece to buy
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