A Tele Vue 9mm Nagler Type 6 in the Celestron AstroMaster 130EQ gives 72x, a 1.14 degree true field and a 1.8 mm exit pupil. The worked calculation and whether it sits in the useful range.

Updated 05 September 2026.

Eyepiece and telescope pairing

Tele Vue 9mm Nagler Type 6 in the Celestron AstroMaster 130EQ: magnification and field

What the Tele Vue 9mm Nagler Type 6 does in the Celestron AstroMaster 130EQ, worked from the published focal lengths and apparent field.

Field of view

ring = 1.14 degrees true
dot = 1.8 mm exit pupil

Computed optics

Magnification
72x650 mm / 9 mm
True field
1.14 degrees82 deg / 72x
Exit pupil
1.8 mm130 mm / 72x
Max useful mag
307xpublished
Barrel match
1.25 in eyepiece in a 1.25 in focuser
Fits

Good fit. In the Celestron AstroMaster 130EQ the Tele Vue 9mm Nagler Type 6 gives 72x with a 1.14 degree true field and a 1.8 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 9 mm is 72x. The true field of view is the eyepiece's 82 degree apparent field divided by that magnification, 1.14 degrees.

The exit pupil, the width of the light beam leaving the eyepiece, is the aperture divided by the magnification, 130 mm over 72x, which is 1.8 mm. That makes this a medium-power general setting.

The eyepiece to buy

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Related

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Questions and answers

Tele Vue 9mm Nagler Type 6 in the Celestron AstroMaster 130EQ: magnification and field?

Good fit. In the Celestron AstroMaster 130EQ the Tele Vue 9mm Nagler Type 6 gives 72x with a 1.14 degree true field and a 1.8 mm exit pupil, inside the telescope's useful range.