How long to image the M18 with the Unistellar eQuinox 2
From a Bortle 6 suburban sky, the Unistellar eQuinox 2 needs about 3 min (52 subs of 4 s) for a solid image of the M18. A quick look takes < 1 min; a showpiece 14 min. Under a Bortle 3 rural sky the solid figure drops to 2 min. At Bortle 6 the limit is a mix of skyglow and read noise. In this scope's field it fills 26% of the frame’s short side.
| Sky | Quick lookTarget obvious, still noisy | SolidClean enough to share | ShowpieceSmooth faint detail, print-worthy |
|---|---|---|---|
| Bortle 1Excellent dark site | < 1 min10 subs | 2 min35 subs | 9 min139 subs |
| Bortle 2Typical dark site | < 1 min10 subs | 2 min36 subs | 9 min141 subs |
| Bortle 3Rural | < 1 min10 subs | 2 min37 subs | 10 min145 subs |
| Bortle 4Rural / suburban transition | < 1 min10 subs | 3 min39 subs | 10 min155 subs |
| Bortle 5Suburban | < 1 min11 subs | 3 min43 subs | 11 min170 subs |
| Bortle 6Bright suburban | < 1 min13 subs | 3 min52 subs | 14 min208 subs |
| Bortle 7Suburban / urban transition | 1 min18 subs | 5 min71 subs | 19 min281 subs |
| Bortle 8City | 2 min25 subs | 7 min99 subs | 26 min393 subs |
| Bortle 9Inner city | 3 min40 subs | 11 min159 subs | 42 min633 subs |
Power and kit for this session
Allowing for slewing, focusing and rejected subs, that is about 5 min of run time. The eQuinox 2’s battery (rated about 11 h) should cover it; a power bank still keeps the phone running the app alive. (Bortle 6, solid image; we allow 30% over the integration time.)
- USB-C power bank 20000mAh 5V 2AUnistellar asks for a 5 V 2 A output; PD is not needed.
- red LED head torchRed light keeps your night vision; white light costs you twenty minutes of dark adaptation every time.
Affiliate links: the retailer pays us a small commission and you pay the same price. These are search links to the named product, not endorsements of a particular listing; check the listing matches your model.
Everything that fits the eQuinox 2 →
How it frames
The M18 is 9′ across. The eQuinox 2 frames 0.76° × 0.57° at 1.33″ per pixel, so it fills 26% of the frame’s short side.
About the M18
A small, sparse open cluster just south of the Omega Nebula. Usually caught in the same frame.
NGC 6613 · Open cluster in Sagittarius · magnitude 6.9 · 9′ · best in Jun, Jul, Aug. Reachable from mid-northern latitudes (UK, northern US, central Europe) and from the south.
Open clusters are the easiest targets in the sky. The stars are bright, so the aim is colour and tight stars rather than depth: short subs, no filter, and stop before the bright members saturate. The nominal time here gets you clean star colour; more integration only adds background stars.
About the Unistellar eQuinox 2
A 114 mm Newtonian with five times the light grasp of a 50 mm refractor. Fixed 4 s subs put it in read-noise territory under dark skies, but the aperture carries it. The published field is 45.6′ × 34.2′, a crop of the sensor.
Fixed 4 s subs in Enhanced Vision; they cannot be changed. No built-in filter. Unistellar sells only a solar filter and says a third-party filter is at your own risk and voids the warranty.
The eQuinox 2 uses fixed 4 s subs, so the only levers you have are the sky you shoot from, the filter, and total time.
Stack across nights. Every smart scope app can continue a stack or you can combine the saved frames on a computer; the figures here are totals, not single-session limits.
Have an image of the M18 from a eQuinox 2? Email it with your total time and sky to [email protected] and it goes here, credited.
Same target, other telescopes
- M18 with the ZWO Seestar S50: 5 min from Bortle 6
- M18 with the ZWO Seestar S50 Pro: 5 min from Bortle 6
- M18 with the ZWO Seestar S30: 5 min from Bortle 6
- M18 with the ZWO Seestar S30 Pro: 5 min from Bortle 6
- M18 with the DwarfLab DWARF 3: 8 min from Bortle 6
- M18 with the DwarfLab DWARF mini: 8 min from Bortle 6
- M18 with the DwarfLab Draco: 15 min from Bortle 6
- M18 with the DwarfLab DWARF II: 14 min from Bortle 6
- M18 with the Vaonis Vespera II: 5 min from Bortle 6
- M18 with the Vaonis Vespera Pro: 9 min from Bortle 6
- M18 with the Vaonis Vespera 3: 5 min from Bortle 6
- M18 with the Vaonis Vespera Pro 2: 9 min from Bortle 6
- M18 with the Unistellar Odyssey: 15 min from Bortle 6
- M18 with the Celestron Origin: 5 min from Bortle 6
- M18 with the Celestron Origin Mark II: 5 min from Bortle 6