Vespera II or eQuinox 2: wide refractor against narrow mirror

Two designs

The Vespera II is a 50 mm refractor at 250 mm, imaging 2.5° by 1.4° on a Sony IMX585, with Vaonis's CovalENS mosaic stretching that to 4.33° by 2.43°. The Unistellar eQuinox 2 is a 114 mm reflector at 450 mm, imaging 34.2 by 45.6 arcminutes, a little over half a degree on the short side.

On the scores that gives a mirror image: the Vespera II leads on field (7.0 against 1.8), the eQuinox 2 on light grasp (8.4 against 4.4) and detail (6.5 against 4.0). Both end at Thin cloud, for different reasons.

Targets

Large nebulae such as the North America, the Rosette or the Veil fit the Vespera II's frame, and need several panels or simply do not fit on the eQuinox 2. Small galaxies and planetary nebulae go the other way: the eQuinox 2 gathers about five times the light through its mirror and puts more pixels across them.

Day to day

The Vespera II's short battery is its main weakness for long winter nights; the eQuinox 2's lack of autofocus is its main weakness in setup. For anyone who wants to process frames on a computer, Vaonis's published FITS output is a clear advantage.

Within each family

The Vespera III keeps the Vespera II's optics and adds an 11 hour battery, a dew heater and multi-night slots, reaching Good seeing. The Vespera Pro II adds a 12.5 MP sensor with 2 µm pixels. On the Unistellar side, the Unistellar Odyssey is lighter and adds autofocus. The Seestar S50 Pro offers a 2.8° field at 2.8 kg in the entry band.

Six to compare