A Explore Scientific 18mm 82 Degree in the Sky-Watcher Skymax 180 gives 150x, a 0.55 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

Explore Scientific 18mm 82 Degree in the Sky-Watcher Skymax 180: magnification and field

What the Explore Scientific 18mm 82 Degree does in the Sky-Watcher Skymax 180, worked from the published focal lengths and apparent field.

Field of view

ring = 0.55 degrees true
dot = 1.2 mm exit pupil

Computed optics

Magnification
150x2700 mm / 18 mm
True field
0.55 degrees82 deg / 150x
Exit pupil
1.2 mm180 mm / 150x
Max useful mag
about 360x2x aperture
Barrel match
1.25 in eyepiece in a 2 in focuser
Fits

Good fit. In the Sky-Watcher Skymax 180 the Explore Scientific 18mm 82 Degree gives 150x with a 0.55 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: 2700 mm divided by 18 mm is 150x. The true field of view is the eyepiece's 82 degree apparent field divided by that magnification, 0.55 degrees.

The exit pupil, the width of the light beam leaving the eyepiece, is the aperture divided by the magnification, 180 mm over 150x, 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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Questions and answers

Explore Scientific 18mm 82 Degree in the Sky-Watcher Skymax 180: magnification and field?

Good fit. In the Sky-Watcher Skymax 180 the Explore Scientific 18mm 82 Degree gives 150x with a 0.55 degree true field and a 1.2 mm exit pupil, inside the telescope's useful range.