A Celestron Omni 6mm Plossl in the Celestron Astro Fi 102 gives 221x, a 0.23 degree true field and a 0.5 mm exit pupil. The worked calculation and whether it sits in the useful range.

Updated 05 September 2026.

Eyepiece and telescope pairing

Celestron Omni 6mm Plossl in the Celestron Astro Fi 102: magnification and field

What the Celestron Omni 6mm Plossl does in the Celestron Astro Fi 102, worked from the published focal lengths and apparent field.

Field of view

ring = 0.23 degrees true
dot = 0.5 mm exit pupil

Computed optics

Magnification
221x1325 mm / 6 mm
True field
0.23 degrees50 deg / 221x
Exit pupil
0.5 mm102 mm / 221x
Max useful mag
241xpublished
Barrel match
1.25 in eyepiece in a 1.25 in focuser
Fits

Good fit. In the Celestron Astro Fi 102 the Celestron Omni 6mm Plossl gives 221x with a 0.23 degree true field and a 0.5 mm exit pupil, inside the telescope's useful range.


Magnification is the telescope focal length divided by the eyepiece focal length: 1325 mm divided by 6 mm is 221x. The true field of view is the eyepiece's 50 degree apparent field divided by that magnification, 0.23 degrees.

The exit pupil, the width of the light beam leaving the eyepiece, is the aperture divided by the magnification, 102 mm over 221x, which is 0.5 mm. That makes this a high-power lunar, planetary and double-star setting.

Questions and answers

Celestron Omni 6mm Plossl in the Celestron Astro Fi 102: magnification and field?

Good fit. In the Celestron Astro Fi 102 the Celestron Omni 6mm Plossl gives 221x with a 0.23 degree true field and a 0.5 mm exit pupil, inside the telescope's useful range.