Eyepiece and telescope pairing

Celestron Omni 15mm Plossl in the Celestron NexStar 8SE: magnification and field

What the Celestron Omni 15mm Plossl does in the Celestron NexStar 8SE, worked from the published focal lengths and apparent field.

Field of view

ring = 0.37 degrees true
dot = 1.5 mm exit pupil

Computed optics

Magnification
135x2032 mm / 15 mm
True field
0.37 degrees50 deg / 135x
Exit pupil
1.5 mm203 mm / 135x
Max useful mag
480xpublished
Barrel match
1.25 in eyepiece in a 2 in focuser
Fits

Good fit. In the Celestron NexStar 8SE the Celestron Omni 15mm Plossl gives 135x with a 0.37 degree true field and a 1.5 mm exit pupil, inside the telescope's useful range.


Magnification is the telescope focal length divided by the eyepiece focal length: 2032 mm divided by 15 mm is 135x. The true field of view is the eyepiece's 50 degree apparent field divided by that magnification, 0.37 degrees.

The exit pupil, the width of the light beam leaving the eyepiece, is the aperture divided by the magnification, 203 mm over 135x, which is 1.5 mm. That makes this a high-power lunar, planetary and double-star setting.