How long to image the Iris Nebula with the Vaonis Vespera II
From a Bortle 6 suburban sky, the Vaonis Vespera II needs about 1 h 53 min (681 subs of 10 s) for a solid image of the Iris Nebula. A quick look takes 28 min; a showpiece 7 h 34 min. Under a Bortle 3 rural sky the solid figure drops to 43 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 21% 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 | 9 min55 subs | 36 min219 subs | 2 h 25 min873 subs |
| Bortle 2Typical dark site | 10 min59 subs | 39 min233 subs | 2 h 35 min930 subs |
| Bortle 3Rural | 11 min65 subs | 43 min260 subs | 2 h 53 min1,037 subs |
| Bortle 4Rural / suburban transition | 14 min82 subs | 54 min325 subs | 3 h 36 min1,298 subs |
| Bortle 5Suburban | 18 min107 subs | 1 h 11 min428 subs | 4 h 45 min1,710 subs |
| Bortle 6Bright suburban | 28 min171 subs | 1 h 53 min681 subs | 7 h 34 min2,723 subs |
| Bortle 7Suburban / urban transition | 48 min291 subs | 3 h 14 min1,164 subs | 13 h4,653 subs |
| Bortle 8City | 1 h 20 min479 subs | 5 h 19 min1,913 subs | 21 h7,649 subs |
| Bortle 9Inner city | 2 h 26 min878 subs | 9 h 45 min3,510 subs | 39 h14,038 subs |
Power and kit for this session
Allowing for slewing, focusing and rejected subs, that is about 2 h 27 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.
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 Vespera II →
How it frames
The Iris Nebula is 18′ across. The Vespera II frames 2.55° × 1.44° at 2.39″ per pixel, so it fills 21% 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 | 43 min260 subs | 1 h 11 min428 subs | 3 h 14 min1,164 subs |
| 20 s | 37 min110 subs | 1 h 05 min195 subs | 3 h 07 min562 subs |
| 30 s | 34 min69 subs | 1 h 02 min125 subs | 3 h 05 min371 subs |
About the Iris Nebula
A blue reflection nebula wrapped in dark dust. No filter helps, and the surrounding dust needs a dark sky and hours.
NGC 7023, Caldwell 4 · Reflection nebula in Cepheus · magnitude 6.8 · 18′ · best in Jul, Aug, Sep. Reachable from mid-northern latitudes (UK, northern US, central Europe) and from the south.
Reflection nebulae are starlight scattered by dust, so they are broadband and blue. A dual-band filter removes almost all of it; do not use one. These are among the faintest structures a smart scope can attempt and the figures run long. A dark sky matters more here than for any other type, and the Moon must be down.
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 Iris Nebula from a Vespera II? Email it with your total time and sky to [email protected] and it goes here, credited.
Same target, other telescopes
- Iris Nebula with the ZWO Seestar S50: 1 h 53 min from Bortle 6
- Iris Nebula with the ZWO Seestar S50 Pro: 2 h 04 min from Bortle 6
- Iris Nebula with the ZWO Seestar S30: 1 h 59 min from Bortle 6
- Iris Nebula with the ZWO Seestar S30 Pro: 2 h 12 min from Bortle 6
- Iris Nebula with the DwarfLab DWARF 3: 2 h 45 min from Bortle 6
- Iris Nebula with the DwarfLab DWARF mini: 1 h 53 min from Bortle 6
- Iris Nebula with the DwarfLab Draco: 1 h 33 min from Bortle 6
- Iris Nebula with the DwarfLab DWARF II: 6 h 29 min from Bortle 6
- Iris Nebula with the Vaonis Vespera Pro: 4 h 14 min from Bortle 6
- Iris Nebula with the Vaonis Vespera 3: 1 h 48 min from Bortle 6
- Iris Nebula with the Vaonis Vespera Pro 2: 4 h 02 min from Bortle 6
- Iris Nebula with the Unistellar eQuinox 2: 1 h 43 min from Bortle 6
- Iris Nebula with the Unistellar Odyssey: 7 h 58 min from Bortle 6
- Iris Nebula with the Celestron Origin: 30 min from Bortle 6
- Iris Nebula with the Celestron Origin Mark II: 41 min from Bortle 6
All telescopes for the Iris Nebula · All targets for the Vespera II