Eyepiece and telescope pairing

Celestron Omni 12mm Plossl in the Celestron NexStar 5SE: magnification and field

What the Celestron Omni 12mm Plossl does in the Celestron NexStar 5SE, worked from the published focal lengths and apparent field.

Field of view

ring = 0.48 degrees true
dot = 1.2 mm exit pupil

Computed optics

Magnification
104x1250 mm / 12 mm
True field
0.48 degrees50 deg / 104x
Exit pupil
1.2 mm125 mm / 104x
Max useful mag
295xpublished
Barrel match
1.25 in eyepiece in a 1.25 in focuser
Fits

Good fit. In the Celestron NexStar 5SE the Celestron Omni 12mm Plossl gives 104x with a 0.48 degree true field and a 1.2 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 12 mm is 104x. The true field of view is the eyepiece's 50 degree apparent field divided by that magnification, 0.48 degrees.

The exit pupil, the width of the light beam leaving the eyepiece, is the aperture divided by the magnification, 125 mm over 104x, which is 1.2 mm. That makes this a high-power lunar, planetary and double-star setting.