Eyepiece and telescope pairing
Tele Vue 4.5mm Delos in the Celestron NexStar 4SE: magnification and field
What the Tele Vue 4.5mm Delos does in the Celestron NexStar 4SE, worked from the published focal lengths and apparent field.
Field of view
ring = 0.24 degrees true
dot = 0.3 mm exit pupil
- Magnification
- 294x1325 mm / 4.5 mm
- True field
- 0.24 degrees72 deg / 294x
- Exit pupil
- 0.3 mm102 mm / 294x
- Max useful mag
- 241xpublished
Computed optics
- Barrel match
- 1.25 in eyepiece in a 1.25 in focuser
Over-powered. At 294x this pair exceeds the published highest useful magnification of about 241x for the Celestron NexStar 4SE, 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: 1325 mm divided by 4.5 mm is 294x. The true field of view is the eyepiece's 72 degree apparent field divided by that magnification, 0.24 degrees.
The exit pupil, the width of the light beam leaving the eyepiece, is the aperture divided by the magnification, 102 mm over 294x, which is 0.3 mm. That makes this a high-power lunar, planetary and double-star setting.
The eyepiece to buy
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