A Celestron X-Cel LX 18mm in the Celestron StarSense Explorer DX 130AZ gives 36x, a 1.66 degree true field and a 3.6 mm exit pupil. The worked calculation and whether it sits in the useful range.

Updated 05 September 2026.

Eyepiece and telescope pairing

Celestron X-Cel LX 18mm in the Celestron StarSense Explorer DX 130AZ: magnification and field

What the Celestron X-Cel LX 18mm does in the Celestron StarSense Explorer DX 130AZ, worked from the published focal lengths and apparent field.

Field of view

ring = 1.66 degrees true
dot = 3.6 mm exit pupil

Computed optics

Magnification
36x650 mm / 18 mm
True field
1.66 degrees60 deg / 36x
Exit pupil
3.6 mm130 mm / 36x
Max useful mag
307xpublished
Barrel match
1.25 in eyepiece in a 1.25 in focuser
Fits

Good fit. In the Celestron StarSense Explorer DX 130AZ the Celestron X-Cel LX 18mm gives 36x with a 1.66 degree true field and a 3.6 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 18 mm is 36x. The true field of view is the eyepiece's 60 degree apparent field divided by that magnification, 1.66 degrees.

The exit pupil, the width of the light beam leaving the eyepiece, is the aperture divided by the magnification, 130 mm over 36x, which is 3.6 mm. That makes this a medium-power general setting.

The eyepiece to buy

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Related

Celestron StarSense Explorer DX 130AZ130 mm f/5
Celestron X-Cel LX 18mm18 mm, 60 deg
Best eyepiece for the Celestron StarSense Explorer DX 130AZexit-pupil match

Questions and answers

Celestron X-Cel LX 18mm in the Celestron StarSense Explorer DX 130AZ: magnification and field?

Good fit. In the Celestron StarSense Explorer DX 130AZ the Celestron X-Cel LX 18mm gives 36x with a 1.66 degree true field and a 3.6 mm exit pupil, inside the telescope's useful range.