A Tele Vue 25mm Plossl in the Celestron AstroMaster 114EQ gives 40x, a 1.25 degree true field and a 2.9 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 AstroMaster 114EQ: magnification and field

What the Tele Vue 25mm Plossl does in the Celestron AstroMaster 114EQ, worked from the published focal lengths and apparent field.

Field of view

ring = 1.25 degrees true
dot = 2.9 mm exit pupil

Computed optics

Magnification
40x1000 mm / 25 mm
True field
1.25 degrees50 deg / 40x
Exit pupil
2.9 mm114 mm / 40x
Max useful mag
269xpublished
Barrel match
1.25 in eyepiece in a 1.25 in focuser
Fits

Good fit. In the Celestron AstroMaster 114EQ the Tele Vue 25mm Plossl gives 40x with a 1.25 degree true field and a 2.9 mm exit pupil, inside the telescope's useful range.

Magnification is the telescope focal length divided by the eyepiece focal length: 1000 mm divided by 25 mm is 40x. The true field of view is the eyepiece's 50 degree apparent field divided by that magnification, 1.25 degrees.

The exit pupil, the width of the light beam leaving the eyepiece, is the aperture divided by the magnification, 114 mm over 40x, which is 2.9 mm. That makes this a medium-power general setting.

The eyepiece to buy

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Related

Celestron AstroMaster 114EQ114 mm f/8.77
Tele Vue 25mm Plossl25 mm, 50 deg
Best eyepiece for the Celestron AstroMaster 114EQexit-pupil match

Questions and answers

Tele Vue 25mm Plossl in the Celestron AstroMaster 114EQ: magnification and field?

Good fit. In the Celestron AstroMaster 114EQ the Tele Vue 25mm Plossl gives 40x with a 1.25 degree true field and a 2.9 mm exit pupil, inside the telescope's useful range.