A Tele Vue 25mm Plossl in the Celestron Astro Fi 130 gives 26x, a 1.92 degree true field and a 5 mm exit pupil. The worked calculation and whether it sits in the useful range.

Updated 05 September 2026.

Eyepiece and telescope pairing

Tele Vue 25mm Plossl in the Celestron Astro Fi 130: magnification and field

What the Tele Vue 25mm Plossl does in the Celestron Astro Fi 130, worked from the published focal lengths and apparent field.

Field of view

ring = 1.92 degrees true
dot = 5 mm exit pupil

Computed optics

Magnification
26x650 mm / 25 mm
True field
1.92 degrees50 deg / 26x
Exit pupil
5 mm130 mm / 26x
Max useful mag
307xpublished
Barrel match
1.25 in eyepiece in a 1.25 in focuser
Fits

Good fit. In the Celestron Astro Fi 130 the Tele Vue 25mm Plossl gives 26x with a 1.92 degree true field and a 5 mm exit pupil, inside the telescope's useful range.

Magnification is the telescope focal length divided by the eyepiece focal length: 650 mm divided by 25 mm is 26x. The true field of view is the eyepiece's 50 degree apparent field divided by that magnification, 1.92 degrees.

The exit pupil, the width of the light beam leaving the eyepiece, is the aperture divided by the magnification, 130 mm over 26x, which is 5 mm. That makes this a low-power, wide-field and deep-sky setting.

The eyepiece to buy

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Related

Celestron Astro Fi 130130 mm f/5
Tele Vue 25mm Plossl25 mm, 50 deg
Best eyepiece for the Celestron Astro Fi 130exit-pupil match

Questions and answers

Tele Vue 25mm Plossl in the Celestron Astro Fi 130: magnification and field?

Good fit. In the Celestron Astro Fi 130 the Tele Vue 25mm Plossl gives 26x with a 1.92 degree true field and a 5 mm exit pupil, inside the telescope's useful range.