How long to image the M55 with the Vaonis Vespera II
From a Bortle 6 suburban sky, the Vaonis Vespera II needs about 14 min (83 subs of 10 s) for a solid image of the M55. A quick look takes 3 min; a showpiece 55 min. Under a Bortle 3 rural sky the solid figure drops to 6 min. At Bortle 6 the limit is skyglow, so a darker site or a filter helps more than longer subs. In this scope's field it fills 22% 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 | 2 min10 subs | 6 min35 subs | 23 min138 subs |
| Bortle 2Typical dark site | 2 min10 subs | 6 min36 subs | 24 min144 subs |
| Bortle 3Rural | 2 min10 subs | 6 min39 subs | 26 min155 subs |
| Bortle 4Rural / suburban transition | 2 min12 subs | 8 min46 subs | 30 min182 subs |
| Bortle 5Suburban | 2 min15 subs | 9 min57 subs | 37 min225 subs |
| Bortle 6Bright suburban | 3 min21 subs | 14 min83 subs | 55 min331 subs |
| Bortle 7Suburban / urban transition | 6 min34 subs | 22 min133 subs | 1 h 29 min532 subs |
| Bortle 8City | 9 min53 subs | 35 min211 subs | 2 h 21 min844 subs |
| Bortle 9Inner city | 16 min95 subs | 1 h 03 min378 subs | 4 h 12 min1,510 subs |
Power and kit for this session
Allowing for slewing, focusing and rejected subs, that is about 18 min of run time. The Vespera II’s battery (rated about 4 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 PD power bank 20000mAh 30WOnly four hours inside; Vaonis specifies a 30 W PD source. C-to-C cable not included.
- Vaonis Vespera hygrometer sensorTriggers the built-in demister automatically; the correct dew accessory for the II.
- red LED head torchRed light keeps your night vision; white light costs you twenty minutes of dark adaptation every time.
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Everything that fits the Vespera II →
How it frames
The M55 is 19′ across. The Vespera II frames 2.55° × 1.44° at 2.39″ per pixel, so it fills 22% of the frame’s short side.
Longer subs
10 s subs by default; Expert Mode manual targets allow 1 to 30 s. Alt-azimuth only, no EQ mode. Time for a solid image by sub length:
| Sub length | Bortle 3 | Bortle 5 | Bortle 7 |
|---|---|---|---|
| 10 s | 6 min39 subs | 9 min57 subs | 22 min133 subs |
| 20 s | 10 min30 subs | 10 min30 subs | 21 min65 subs |
| 30 s | 15 min30 subs | 15 min30 subs | 21 min43 subs |
About the M55
A large, loose globular that resolves easily but sits low for northern imagers.
NGC 6809 · Globular cluster in Sagittarius · magnitude 6.3 · 19′ · best in Jun, Jul, Aug. Reachable from mid-northern latitudes (UK, northern US, central Europe) and from the south.
Globular clusters are point sources packed tight, so they come quickly: the core resolves into stars within a handful of minutes on any smart scope. More time deepens the halo and pulls in the faint outer members. Use short subs so the core does not saturate into a white blob, and no filter.
About the Vaonis Vespera II
A 50 mm quadruplet on an 8 MP sensor with Vaonis’s mosaic mode for wide fields. Same optics class as the Seestar S50, four times the pixels.
10 s subs by default; Expert Mode manual targets allow 1 to 30 s. Alt-azimuth only, no EQ mode. Optional clip-on Vaonis filters: dual-band, light-pollution (CLS) and solar; the app detects which is fitted.
Longer subs matter most under dark skies, where read noise rather than skyglow sets the floor. From a city the difference between 10 s and 30 s subs is small; from a rural site it can halve the total time, especially with a dual-band filter in place.
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 M55 from a Vespera II? Email it with your total time and sky to [email protected] and it goes here, credited.
Same target, other telescopes
- M55 with the ZWO Seestar S50: 14 min from Bortle 6
- M55 with the ZWO Seestar S50 Pro: 15 min from Bortle 6
- M55 with the ZWO Seestar S30: 14 min from Bortle 6
- M55 with the ZWO Seestar S30 Pro: 16 min from Bortle 6
- M55 with the DwarfLab DWARF 3: 20 min from Bortle 6
- M55 with the DwarfLab DWARF mini: 14 min from Bortle 6
- M55 with the DwarfLab Draco: 15 min from Bortle 6
- M55 with the DwarfLab DWARF II: 46 min from Bortle 6
- M55 with the Vaonis Vespera Pro: 31 min from Bortle 6
- M55 with the Vaonis Vespera 3: 13 min from Bortle 6
- M55 with the Vaonis Vespera Pro 2: 29 min from Bortle 6
- M55 with the Unistellar eQuinox 2: 12 min from Bortle 6
- M55 with the Unistellar Odyssey: 54 min from Bortle 6
- M55 with the Celestron Origin: 5 min from Bortle 6
- M55 with the Celestron Origin Mark II: 5 min from Bortle 6