A Tele Vue 41mm Panoptic in the Sky-Watcher Evostar 72ED gives 10x, a 6.64 degree true field and a 7 mm exit pupil. The worked calculation and whether it sits in the useful range.

Updated 05 September 2026.

Eyepiece and telescope pairing

Tele Vue 41mm Panoptic in the Sky-Watcher Evostar 72ED: magnification and field

What the Tele Vue 41mm Panoptic does in the Sky-Watcher Evostar 72ED, worked from the published focal lengths and apparent field.

Field of view

ring = 6.64 degrees true
dot = 7 mm exit pupil

Computed optics

Magnification
10x420 mm / 41 mm
True field
6.64 degrees68 deg / 10x
Exit pupil
7 mm72 mm / 10x
Max useful mag
170xpublished
Barrel match
2 in eyepiece in a 2 in focuser
Needs adapter

Works, but the 7 mm exit pupil is wider than a dark-adapted pupil of about 7 mm, so the outer light is wasted and the sky background looks brighter. Fine for framing, but a slightly shorter eyepiece uses the aperture better.

Magnification is the telescope focal length divided by the eyepiece focal length: 420 mm divided by 41 mm is 10x. The true field of view is the eyepiece's 68 degree apparent field divided by that magnification, 6.64 degrees.

The exit pupil, the width of the light beam leaving the eyepiece, is the aperture divided by the magnification, 72 mm over 10x, which is 7 mm. That makes this a low-power, wide-field and deep-sky setting.

The eyepiece to buy

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Related

Sky-Watcher Evostar 72ED72 mm f/5.8
Tele Vue 41mm Panoptic41 mm, 68 deg
Best eyepiece for the Sky-Watcher Evostar 72EDexit-pupil match

Questions and answers

Tele Vue 41mm Panoptic in the Sky-Watcher Evostar 72ED: magnification and field?

Works, but the 7 mm exit pupil is wider than a dark-adapted pupil of about 7 mm, so the outer light is wasted and the sky background looks brighter. Fine for framing, but a slightly shorter eyepiece uses the aperture better.