Eyepiece and telescope pairing
Explore Scientific 8.8mm 82 Degree in the Sky-Watcher Evostar 80ED: magnification and field
What the Explore Scientific 8.8mm 82 Degree does in the Sky-Watcher Evostar 80ED, worked from the published focal lengths and apparent field.
Field of view
ring = 1.2 degrees true
dot = 1.2 mm exit pupil
- Magnification
- 68x600 mm / 8.8 mm
- True field
- 1.2 degrees82 deg / 68x
- Exit pupil
- 1.2 mm80 mm / 68x
- Max useful mag
- 189xpublished
Computed optics
- Barrel match
- 1.25 in eyepiece in a 2 in focuser
Good fit. In the Sky-Watcher Evostar 80ED the Explore Scientific 8.8mm 82 Degree gives 68x with a 1.2 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: 600 mm divided by 8.8 mm is 68x. The true field of view is the eyepiece's 82 degree apparent field divided by that magnification, 1.2 degrees.
The exit pupil, the width of the light beam leaving the eyepiece, is the aperture divided by the magnification, 80 mm over 68x, 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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