How long to image the Dumbbell Nebula with the ZWO Seestar S30
From a Bortle 6 suburban sky, the ZWO Seestar S30 needs about 23 min (136 subs of 10 s with the built-in dual-band (LP filter) filter) for a solid image of the Dumbbell Nebula. A quick look takes 6 min; a showpiece 1 h 30 min. Under a Bortle 3 rural sky the solid figure drops to 18 min. At Bortle 6 the limit is a mix of skyglow and read noise. 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 | 4 min27 subs | 18 min106 subs | 1 h 11 min424 subs |
| Bortle 2Typical dark site | 4 min27 subs | 18 min107 subs | 1 h 11 min428 subs |
| Bortle 3Rural | 5 min28 subs | 18 min109 subs | 1 h 12 min435 subs |
| Bortle 4Rural / suburban transition | 5 min29 subs | 19 min113 subs | 1 h 15 min451 subs |
| Bortle 5Suburban | 5 min30 subs | 20 min120 subs | 1 h 19 min477 subs |
| Bortle 6Bright suburban | 6 min34 subs | 23 min136 subs | 1 h 30 min541 subs |
| Bortle 7Suburban / urban transition | 7 min42 subs | 28 min166 subs | 1 h 50 min662 subs |
| Bortle 8City | 9 min54 subs | 35 min213 subs | 2 h 22 min851 subs |
| Bortle 9Inner city | 13 min79 subs | 52 min314 subs | 3 h 29 min1,253 subs |
Power and kit for this session
Allowing for slewing, focusing and rejected subs, that is about 29 min of run time. The Seestar S30’s battery (rated about 6 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 10000mAh 5V 3A6,000 mAh inside; a 10,000 mAh 5 V 3 A bank roughly doubles a session.
- Seestar S30 dew shieldHeater is built in; a cheap shield reduces dew and stray light.
- 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 Dumbbell Nebula is 8′ × 5.7′ across. The Seestar S30 frames 2.13° × 1.20° at 3.99″ per pixel, so it fills 11% of the frame’s short side.
Longer subs
10, 20 and 30 s in Alt-Az; 60 s only in EQ mode, which needs the TH10 head. Time for a solid image by sub length:
| Sub length | Bortle 3 | Bortle 5 | Bortle 7 |
|---|---|---|---|
| 10 s | 18 min109 subs | 20 min120 subs | 28 min166 subs |
| 20 s | 14 min43 subs | 16 min48 subs | 24 min71 subs |
| 30 s | 15 min30 subs | 15 min30 subs | 22 min45 subs |
| 60 s | 30 min30 subs | 30 min30 subs | 30 min30 subs |
With and without the dual-band filter
| Filter | Bortle 3 | Bortle 5 | Bortle 7 |
|---|---|---|---|
| UV/IR-cut (no light-pollution filter) | 14 min83 subs | 20 min118 subs | 45 min269 subs |
| dual-band (LP filter) | 18 min109 subs | 20 min120 subs | 28 min166 subs |
About the Dumbbell Nebula
The biggest, brightest planetary nebula for northern observers. Bright enough to look good in twenty minutes, and dual-band brings out the outer shell.
M27, NGC 6853 · Planetary nebula in Vulpecula · magnitude 7.4 · 8′ × 5.7′ · best in Jun, Jul, Aug. Reachable from mid-northern latitudes (UK, northern US, central Europe) and from the south.
Planetary nebulae are small but intensely bright per pixel in OIII and H-alpha, so they respond very well to a dual-band filter and do not need much time for the main shell. The faint outer halos most of them have are a different proposition and need hours. Keep subs short if the central region saturates.
About the ZWO Seestar S30
Wider and lighter than the S50 with the same 2.9 µm pixels, so its per-pixel speed on extended targets is close despite the smaller aperture. Ideal for big nebulae.
10, 20 and 30 s in Alt-Az; 60 s only in EQ mode, which needs the TH10 head. Built-in UV/IR-cut, dual-band (OIII 30 nm / Hα 20 nm) and dark filters.
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 60 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 Dumbbell Nebula from a Seestar S30? Email it with your total time and sky to [email protected] and it goes here, credited.
Same target, other telescopes
- Dumbbell Nebula with the ZWO Seestar S50: 20 min from Bortle 6
- Dumbbell Nebula with the ZWO Seestar S50 Pro: 22 min from Bortle 6
- Dumbbell Nebula with the ZWO Seestar S30 Pro: 24 min from Bortle 6
- Dumbbell Nebula with the DwarfLab DWARF 3: 27 min from Bortle 6
- Dumbbell Nebula with the DwarfLab DWARF mini: 20 min from Bortle 6
- Dumbbell Nebula with the DwarfLab Draco: 16 min from Bortle 6
- Dumbbell Nebula with the DwarfLab DWARF II: 1 h 30 min from Bortle 6
- Dumbbell Nebula with the Vaonis Vespera II: 27 min from Bortle 6
- Dumbbell Nebula with the Vaonis Vespera Pro: 1 h from Bortle 6
- Dumbbell Nebula with the Vaonis Vespera 3: 26 min from Bortle 6
- Dumbbell Nebula with the Vaonis Vespera Pro 2: 57 min from Bortle 6
- Dumbbell Nebula with the Unistellar eQuinox 2: 24 min from Bortle 6
- Dumbbell Nebula with the Unistellar Odyssey: 1 h 47 min from Bortle 6
- Dumbbell Nebula with the Celestron Origin: 7 min from Bortle 6
- Dumbbell Nebula with the Celestron Origin Mark II: 10 min from Bortle 6
All telescopes for the Dumbbell Nebula · All targets for the Seestar S30