A Tele Vue 6mm Ethos in the Sky-Watcher Evostar 80ED gives 100x, a 1 degree true field and a 0.8 mm exit pupil. The worked calculation and whether it sits in the useful range.

Updated 05 September 2026.

Eyepiece and telescope pairing

Tele Vue 6mm Ethos in the Sky-Watcher Evostar 80ED: magnification and field

What the Tele Vue 6mm Ethos does in the Sky-Watcher Evostar 80ED, worked from the published focal lengths and apparent field.

Field of view

ring = 1 degrees true
dot = 0.8 mm exit pupil

Computed optics

Magnification
100x600 mm / 6 mm
True field
1 degrees100 deg / 100x
Exit pupil
0.8 mm80 mm / 100x
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 Tele Vue 6mm Ethos gives 100x with a 1 degree true field and a 0.8 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 6 mm is 100x. The true field of view is the eyepiece's 100 degree apparent field divided by that magnification, 1 degrees.

The exit pupil, the width of the light beam leaving the eyepiece, is the aperture divided by the magnification, 80 mm over 100x, which is 0.8 mm. That makes this a high-power lunar, planetary and double-star setting.

The eyepiece to buy

Shop Tele Vue 6mm Ethos on AmazonaffiliateFind Tele Vue 6mm Ethos on eBayaffiliate

Related

Sky-Watcher Evostar 80ED80 mm f/7.5
Tele Vue 6mm Ethos6 mm, 100 deg
Best eyepiece for the Sky-Watcher Evostar 80EDexit-pupil match

Questions and answers

Tele Vue 6mm Ethos in the Sky-Watcher Evostar 80ED: magnification and field?

Good fit. In the Sky-Watcher Evostar 80ED the Tele Vue 6mm Ethos gives 100x with a 1 degree true field and a 0.8 mm exit pupil, inside the telescope's useful range.