A Tele Vue 13mm Nagler Type 6 in the Celestron AstroMaster 114EQ gives 77x, a 1.07 degree true field and a 1.5 mm exit pupil. The worked calculation and whether it sits in the useful range.

Updated 05 September 2026.

Eyepiece and telescope pairing

Tele Vue 13mm Nagler Type 6 in the Celestron AstroMaster 114EQ: magnification and field

What the Tele Vue 13mm Nagler Type 6 does in the Celestron AstroMaster 114EQ, worked from the published focal lengths and apparent field.

Field of view

ring = 1.07 degrees true
dot = 1.5 mm exit pupil

Computed optics

Magnification
77x1000 mm / 13 mm
True field
1.07 degrees82 deg / 77x
Exit pupil
1.5 mm114 mm / 77x
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 13mm Nagler Type 6 gives 77x with a 1.07 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: 1000 mm divided by 13 mm is 77x. The true field of view is the eyepiece's 82 degree apparent field divided by that magnification, 1.07 degrees.

The exit pupil, the width of the light beam leaving the eyepiece, is the aperture divided by the magnification, 114 mm over 77x, which is 1.5 mm. That makes this a high-power lunar, planetary and double-star setting.

The eyepiece to buy

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Related

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Questions and answers

Tele Vue 13mm Nagler Type 6 in the Celestron AstroMaster 114EQ: magnification and field?

Good fit. In the Celestron AstroMaster 114EQ the Tele Vue 13mm Nagler Type 6 gives 77x with a 1.07 degree true field and a 1.5 mm exit pupil, inside the telescope's useful range.