How long to image the NGC 7331 with the Vaonis Vespera 3
From a Bortle 6 suburban sky, the Vaonis Vespera 3 needs about 2 h 01 min (728 subs of 10 s) for a solid image of the NGC 7331. A quick look takes 30 min; a showpiece 8 h 05 min. Under a Bortle 3 rural sky the solid figure drops to 47 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 | 10 min60 subs | 39 min237 subs | 2 h 38 min947 subs |
| Bortle 2Typical dark site | 10 min63 subs | 42 min252 subs | 2 h 48 min1,007 subs |
| Bortle 3Rural | 12 min71 subs | 47 min281 subs | 3 h 07 min1,121 subs |
| Bortle 4Rural / suburban transition | 15 min88 subs | 58 min350 subs | 3 h 53 min1,398 subs |
| Bortle 5Suburban | 19 min115 subs | 1 h 16 min459 subs | 5 h 06 min1,835 subs |
| Bortle 6Bright suburban | 30 min182 subs | 2 h 01 min728 subs | 8 h 05 min2,909 subs |
| Bortle 7Suburban / urban transition | 52 min310 subs | 3 h 26 min1,239 subs | 14 h4,955 subs |
| Bortle 8City | 1 h 25 min509 subs | 5 h 39 min2,033 subs | 23 h8,132 subs |
| Bortle 9Inner city | 2 h 35 min932 subs | 10 h3,727 subs | 41 h14,907 subs |
Power and kit for this session
Allowing for slewing, focusing and rejected subs, that is about 2 h 38 min of run time. The Vespera 3’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 30WVaonis says an external bank extends sessions; 30 W PD as for the II and Pro.
- red LED head torchRed light keeps your night vision; white light costs you twenty minutes of dark adaptation every time.
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How it frames
The NGC 7331 is 10′ × 4′ across. The Vespera 3 frames 2.60° × 1.46° at 2.44″ 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 widens the field to 4.3° × 2.4°. Time for a solid image by sub length:
| Sub length | Bortle 3 | Bortle 5 | Bortle 7 |
|---|---|---|---|
| 10 s | 47 min281 subs | 1 h 16 min459 subs | 3 h 26 min1,239 subs |
| 20 s | 40 min121 subs | 1 h 10 min210 subs | 3 h 20 min600 subs |
| 30 s | 38 min76 subs | 1 h 08 min136 subs | 3 h 18 min396 subs |
About the NGC 7331
A tilted spiral often compared to the Milky Way, with a group of background galaxies alongside. Stephan's Quintet is half a degree away.
Caldwell 30 · Galaxy in Pegasus · magnitude 9.5 · 10′ × 4′ · best in Aug, Sep, Oct. Reachable from mid-northern latitudes (UK, northern US, central Europe) and from the south.
Galaxies are broadband targets: their light is mostly starlight spread across the spectrum, so a dual-band filter throws most of it away and makes things slower, not faster. Shoot without a filter (or with a plain UV/IR cut) and rely on total time and a dark sky. The core of a galaxy is usually many times brighter than its outer disc, so a short stack shows the nucleus long before the arms; the figures here are for the arms and disc, not the core.
Field rotation in Alt-Az mode crops the edges of the stack over a long session, so on a big galaxy re-centre now and then or use EQ mode where your scope supports it.
About the Vaonis Vespera 3
The 2026 Vespera: same 50 mm quadruplet class as the II on an 8 MP IMX585, with a 24 MP mosaic mode and 11 hours of battery. Per pixel it behaves like a Seestar S50 Pro without the built-in dual-band filter.
10 s subs by default; Expert Mode manual targets allow 1 to 30 s. Alt-azimuth only; CovalENS mosaic widens the field to 4.3° × 2.4°. Optional clip-on Vaonis filters: dual-band, light-pollution (CLS) and solar. The new optical baffle is not a substitute for a CLS filter.
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 NGC 7331 from a Vespera 3? Email it with your total time and sky to [email protected] and it goes here, credited.
Same target, other telescopes
- NGC 7331 with the ZWO Seestar S50: 2 h 07 min from Bortle 6
- NGC 7331 with the ZWO Seestar S50 Pro: 2 h 19 min from Bortle 6
- NGC 7331 with the ZWO Seestar S30: 2 h 13 min from Bortle 6
- NGC 7331 with the ZWO Seestar S30 Pro: 2 h 27 min from Bortle 6
- NGC 7331 with the DwarfLab DWARF 3: 3 h 04 min from Bortle 6
- NGC 7331 with the DwarfLab DWARF mini: 2 h 06 min from Bortle 6
- NGC 7331 with the DwarfLab Draco: 1 h 44 min from Bortle 6
- NGC 7331 with the DwarfLab DWARF II: 7 h 14 min from Bortle 6
- NGC 7331 with the Vaonis Vespera II: 2 h 07 min from Bortle 6
- NGC 7331 with the Vaonis Vespera Pro: 4 h 44 min from Bortle 6
- NGC 7331 with the Vaonis Vespera Pro 2: 4 h 31 min from Bortle 6
- NGC 7331 with the Unistellar eQuinox 2: 1 h 55 min from Bortle 6
- NGC 7331 with the Unistellar Odyssey: 8 h 52 min from Bortle 6
- NGC 7331 with the Celestron Origin: 34 min from Bortle 6
- NGC 7331 with the Celestron Origin Mark II: 46 min from Bortle 6
All telescopes for the NGC 7331 · All targets for the Vespera 3