How long to image the M28 with the Vaonis Vespera Pro 2
From a Bortle 6 suburban sky, the Vaonis Vespera Pro 2 needs about 13 min (80 subs of 10 s) for a solid image of the M28. A quick look takes 3 min; a showpiece 53 min. Under a Bortle 3 rural sky the solid figure drops to 7 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 11% 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 min11 subs | 7 min42 subs | 28 min167 subs |
| Bortle 2Typical dark site | 2 min11 subs | 7 min43 subs | 29 min172 subs |
| Bortle 3Rural | 2 min12 subs | 7 min45 subs | 30 min180 subs |
| Bortle 4Rural / suburban transition | 2 min13 subs | 8 min51 subs | 34 min202 subs |
| Bortle 5Suburban | 2 min15 subs | 10 min59 subs | 39 min235 subs |
| Bortle 6Bright suburban | 3 min20 subs | 13 min80 subs | 53 min317 subs |
| Bortle 7Suburban / urban transition | 5 min30 subs | 20 min119 subs | 1 h 19 min473 subs |
| Bortle 8City | 7 min45 subs | 30 min179 subs | 1 h 59 min716 subs |
| Bortle 9Inner city | 13 min78 subs | 51 min309 subs | 3 h 25 min1,233 subs |
Power and kit for this session
Allowing for slewing, focusing and rejected subs, that is about 17 min of run time. The Vespera Pro 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 PD power bank 20000mAh 30WExternal bank extends the 11 h battery.
- 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 Pro 2 →
How it frames
The M28 is 11′ across. The Vespera Pro 2 frames 1.65° × 1.65° at 1.68″ per pixel, so it fills 11% 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; CovalENS mosaic gives 3.2° × 3.2° at 50 MP. Time for a solid image by sub length:
| Sub length | Bortle 3 | Bortle 5 | Bortle 7 |
|---|---|---|---|
| 10 s | 7 min45 subs | 10 min59 subs | 20 min119 subs |
| 20 s | 10 min30 subs | 10 min30 subs | 19 min58 subs |
| 30 s | 15 min30 subs | 15 min30 subs | 19 min38 subs |
About the M28
A compact globular near Lambda Sagittarii, a degree from M22. Small and quick.
NGC 6626 · Globular cluster in Sagittarius · magnitude 6.8 · 11′ · 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 Pro 2
The square-sensor 2026 Vespera with 2 µm pixels. Sharper than the Vespera 3 on small targets and correspondingly slower per pixel; the 12.5 MP square frame suits galaxies and planetaries.
10 s subs by default; Expert Mode manual targets allow 1 to 30 s. Alt-azimuth only; CovalENS mosaic gives 3.2° × 3.2° at 50 MP. Optional clip-on Vaonis filters: dual-band, light-pollution (CLS) and solar.
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 M28 from a Vespera Pro 2? Email it with your total time and sky to [email protected] and it goes here, credited.
Same target, other telescopes
- M28 with the ZWO Seestar S50: 6 min from Bortle 6
- M28 with the ZWO Seestar S50 Pro: 7 min from Bortle 6
- M28 with the ZWO Seestar S30: 7 min from Bortle 6
- M28 with the ZWO Seestar S30 Pro: 7 min from Bortle 6
- M28 with the DwarfLab DWARF 3: 9 min from Bortle 6
- M28 with the DwarfLab DWARF mini: 8 min from Bortle 6
- M28 with the DwarfLab Draco: 15 min from Bortle 6
- M28 with the DwarfLab DWARF II: 20 min from Bortle 6
- M28 with the Vaonis Vespera II: 6 min from Bortle 6
- M28 with the Vaonis Vespera Pro: 14 min from Bortle 6
- M28 with the Vaonis Vespera 3: 6 min from Bortle 6
- M28 with the Unistellar eQuinox 2: 5 min from Bortle 6
- M28 with the Unistellar Odyssey: 23 min from Bortle 6
- M28 with the Celestron Origin: 5 min from Bortle 6
- M28 with the Celestron Origin Mark II: 5 min from Bortle 6
All telescopes for the M28 · All targets for the Vespera Pro 2