Optical reference
Sky-Watcher Evostar 72ED: aperture, focal length and eyepiece fit
What the Sky-Watcher Evostar 72ED measures, the magnification and true field each eyepiece produces in it, and the barrel, mount payload and camera adapter that fit.
Published specifications
Eyepiece ladder
2 pairings| Pairing | Magnification | True field |
|---|---|---|
| Tele Vue 3.5mm Nagler Type 6 in the Sky-Watcher Evostar 72ED | 120x | 0.68 deg |
| Celestron Omni 12mm Plossl in the Sky-Watcher Evostar 72ED | 35x | 1.43 deg |
The Evostar 72ED is a 72 mm f/5.8 ED doublet, a short, sharp apochromatic refractor much used for wide-field imaging. Its 420 mm focal length gives very wide true fields and controls false colour well for a small doublet.
Because magnification is the telescope's 420 mm focal length divided by the eyepiece focal length, a 25 mm eyepiece gives 17x here and a 10 mm eyepiece gives 42x. The highest useful magnification is the published 170x, beyond which the image dims and softens without showing more detail.
The focuser takes 2 in eyepieces, so long 2 in wide-field eyepieces such as the Omni 56 mm fit as well as 1.25 in ones.