Eyepiece and telescope pairing
Tele Vue 17.3mm Delos in the Celestron NexStar 5SE: magnification and field
What the Tele Vue 17.3mm Delos does in the Celestron NexStar 5SE, worked from the published focal lengths and apparent field.
Field of view
ring = 1 degrees true
dot = 1.7 mm exit pupil
- Magnification
- 72x1250 mm / 17.3 mm
- True field
- 1 degrees72 deg / 72x
- Exit pupil
- 1.7 mm125 mm / 72x
- Max useful mag
- 295xpublished
Computed optics
- Barrel match
- 1.25 in eyepiece in a 1.25 in focuser
Good fit. In the Celestron NexStar 5SE the Tele Vue 17.3mm Delos gives 72x with a 1 degree true field and a 1.7 mm exit pupil, inside the telescope's useful range.
Magnification is the telescope focal length divided by the eyepiece focal length: 1250 mm divided by 17.3 mm is 72x. The true field of view is the eyepiece's 72 degree apparent field divided by that magnification, 1 degrees.
The exit pupil, the width of the light beam leaving the eyepiece, is the aperture divided by the magnification, 125 mm over 72x, which is 1.7 mm. That makes this a medium-power general setting.
The eyepiece to buy
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