How long to image the Dumbbell Nebula with the ZWO Seestar S50
From a Bortle 6 suburban sky, the ZWO Seestar S50 needs about 20 min (121 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 5 min; a showpiece 1 h 20 min. Under a Bortle 3 rural sky the solid figure drops to 16 min. At Bortle 6 the limit is a mix of skyglow and read noise. In this scope's field it fills 19% 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 min23 subs | 15 min92 subs | 1 h 01 min366 subs |
| Bortle 2Typical dark site | 4 min24 subs | 15 min93 subs | 1 h 02 min370 subs |
| Bortle 3Rural | 4 min24 subs | 16 min94 subs | 1 h 03 min376 subs |
| Bortle 4Rural / suburban transition | 4 min25 subs | 16 min99 subs | 1 h 05 min393 subs |
| Bortle 5Suburban | 4 min27 subs | 17 min105 subs | 1 h 10 min419 subs |
| Bortle 6Bright suburban | 5 min31 subs | 20 min121 subs | 1 h 20 min482 subs |
| Bortle 7Suburban / urban transition | 6 min38 subs | 25 min151 subs | 1 h 41 min604 subs |
| Bortle 8City | 8 min50 subs | 33 min198 subs | 2 h 12 min792 subs |
| Bortle 9Inner city | 12 min75 subs | 50 min299 subs | 3 h 19 min1,195 subs |
Power and kit for this session
Allowing for slewing, focusing and rejected subs, that is about 26 min of run time. The Seestar S50’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 20000mAh 5V 3AThe S50 draws 5 V 3 A over USB-C and runs while charging; no PD needed.
- Seestar S50 dew shieldThe built-in heater copes with most nights; a shield helps in heavy dew and blocks 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 S50 frames 1.28° × 0.72° at 2.39″ per pixel, so it fills 19% of the frame’s short side.
Longer subs
10, 20 and 30 s in Alt-Az; 60 s only in EQ mode (app 2.5 and later). Time for a solid image by sub length:
| Sub length | Bortle 3 | Bortle 5 | Bortle 7 |
|---|---|---|---|
| 10 s | 16 min94 subs | 17 min105 subs | 25 min151 subs |
| 20 s | 13 min39 subs | 15 min45 subs | 22 min68 subs |
| 30 s | 15 min30 subs | 15 min30 subs | 21 min43 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) | 13 min76 subs | 18 min111 subs | 44 min262 subs |
| dual-band (LP filter) | 16 min94 subs | 17 min105 subs | 25 min151 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 S50
The scope that made smart astrophotography mainstream. 50 mm triplet, 2 MP sensor, dual-band filter on a wheel. Alt-Az stacking at 10 s, EQ mode unlocks 60 s. Out of production since 2026 and replaced by the S50 Pro, but there are a great many in use.
10, 20 and 30 s in Alt-Az; 60 s only in EQ mode (app 2.5 and later). Built-in dual-band light-pollution filter, switchable in the app.
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 S50? 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 Pro: 22 min from Bortle 6
- Dumbbell Nebula with the ZWO Seestar S30: 23 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 S50