Eyepiece and telescope pairing
Celestron Omni 4mm Plossl in the Celestron C6 optical tube: magnification and field
What the Celestron Omni 4mm Plossl does in the Celestron C6 optical tube, worked from the published focal lengths and apparent field.
Field of view
ring = 0.13 degrees true
dot = 0.4 mm exit pupil
- Magnification
- 375x1500 mm / 4 mm
- True field
- 0.13 degrees50 deg / 375x
- Exit pupil
- 0.4 mm150 mm / 375x
- Max useful mag
- 354xpublished
Computed optics
- Barrel match
- 1.25 in eyepiece in a 1.25 in focuser
Over-powered. At 375x this pair exceeds the published highest useful magnification of about 354x for the Celestron C6 optical tube, 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 4 mm is 375x. The true field of view is the eyepiece's 50 degree apparent field divided by that magnification, 0.13 degrees.
The exit pupil, the width of the light beam leaving the eyepiece, is the aperture divided by the magnification, 150 mm over 375x, which is 0.4 mm. That makes this a high-power lunar, planetary and double-star setting.
The eyepiece to buy
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