A Tele Vue 13mm Nagler Type 6 in the Celestron C14 optical tube gives 301x, a 0.27 degree true field and a 1.2 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 C14 optical tube: magnification and field

What the Tele Vue 13mm Nagler Type 6 does in the Celestron C14 optical tube, worked from the published focal lengths and apparent field.

Field of view

ring = 0.27 degrees true
dot = 1.2 mm exit pupil

Computed optics

Magnification
301x3910 mm / 13 mm
True field
0.27 degrees82 deg / 301x
Exit pupil
1.2 mm356 mm / 301x
Max useful mag
840xpublished
Barrel match
1.25 in eyepiece in a 2 in focuser
Fits

Good fit. In the Celestron C14 optical tube the Tele Vue 13mm Nagler Type 6 gives 301x with a 0.27 degree true field and a 1.2 mm exit pupil, inside the telescope's useful range.

Magnification is the telescope focal length divided by the eyepiece focal length: 3910 mm divided by 13 mm is 301x. The true field of view is the eyepiece's 82 degree apparent field divided by that magnification, 0.27 degrees.

The exit pupil, the width of the light beam leaving the eyepiece, is the aperture divided by the magnification, 356 mm over 301x, which is 1.2 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 C14 optical tube: magnification and field?

Good fit. In the Celestron C14 optical tube the Tele Vue 13mm Nagler Type 6 gives 301x with a 0.27 degree true field and a 1.2 mm exit pupil, inside the telescope's useful range.