A Explore Scientific 11mm 82 Degree in the Sky-Watcher Evostar 80ED gives 55x, a 1.5 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

Explore Scientific 11mm 82 Degree in the Sky-Watcher Evostar 80ED: magnification and field

What the Explore Scientific 11mm 82 Degree does in the Sky-Watcher Evostar 80ED, worked from the published focal lengths and apparent field.

Field of view

ring = 1.5 degrees true
dot = 1.5 mm exit pupil

Computed optics

Magnification
55x600 mm / 11 mm
True field
1.5 degrees82 deg / 55x
Exit pupil
1.5 mm80 mm / 55x
Max useful mag
189xpublished
Barrel match
1.25 in eyepiece in a 2 in focuser
Fits

Good fit. In the Sky-Watcher Evostar 80ED the Explore Scientific 11mm 82 Degree gives 55x with a 1.5 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: 600 mm divided by 11 mm is 55x. The true field of view is the eyepiece's 82 degree apparent field divided by that magnification, 1.5 degrees.

The exit pupil, the width of the light beam leaving the eyepiece, is the aperture divided by the magnification, 80 mm over 55x, 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

Explore Scientific 11mm 82 Degree in the Sky-Watcher Evostar 80ED: magnification and field?

Good fit. In the Sky-Watcher Evostar 80ED the Explore Scientific 11mm 82 Degree gives 55x with a 1.5 degree true field and a 1.5 mm exit pupil, inside the telescope's useful range.