How long to image the Helix Nebula with the ZWO Seestar S50
From a Bortle 6 suburban sky, the ZWO Seestar S50 needs about 2 h (720 subs of 10 s with the built-in dual-band (LP filter) filter) for a solid image of the Helix Nebula. A quick look takes 30 min; a showpiece 8 h. Under a Bortle 3 rural sky the solid figure drops to 1 h 23 min. At Bortle 6 the limit is a mix of skyglow and read noise. In this scope's field it fills 58% 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 | 20 min119 subs | 1 h 19 min474 subs | 5 h 15 min1,893 subs |
| Bortle 2Typical dark site | 20 min121 subs | 1 h 20 min481 subs | 5 h 21 min1,924 subs |
| Bortle 3Rural | 21 min124 subs | 1 h 23 min496 subs | 5 h 30 min1,981 subs |
| Bortle 4Rural / suburban transition | 22 min133 subs | 1 h 28 min530 subs | 5 h 53 min2,119 subs |
| Bortle 5Suburban | 24 min147 subs | 1 h 37 min585 subs | 6 h 30 min2,339 subs |
| Bortle 6Bright suburban | 30 min180 subs | 2 h720 subs | 8 h2,878 subs |
| Bortle 7Suburban / urban transition | 41 min244 subs | 2 h 43 min976 subs | 11 h3,904 subs |
| Bortle 8City | 57 min344 subs | 3 h 49 min1,375 subs | 15 h5,498 subs |
| Bortle 9Inner city | 1 h 33 min557 subs | 6 h 11 min2,225 subs | 25 h8,897 subs |
Power and kit for this session
Allowing for slewing, focusing and rejected subs, that is about 2 h 36 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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Everything that fits the Seestar S50 →
How it frames
The Helix Nebula is 25′ × 22′ across. The Seestar S50 frames 1.28° × 0.72° at 2.39″ per pixel, so it fills 58% 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 | 1 h 23 min496 subs | 1 h 37 min585 subs | 2 h 43 min976 subs |
| 20 s | 59 min178 subs | 1 h 14 min223 subs | 2 h 19 min419 subs |
| 30 s | 51 min103 subs | 1 h 06 min133 subs | 2 h 12 min264 subs |
| 60 s | 44 min44 subs | 59 min59 subs | 2 h 04 min124 subs |
With and without the dual-band filter
| Filter | Bortle 3 | Bortle 5 | Bortle 7 |
|---|---|---|---|
| UV/IR-cut (no light-pollution filter) | 1 h 11 min429 subs | 2 h721 subs | 5 h 33 min1,999 subs |
| dual-band (LP filter) | 1 h 23 min496 subs | 1 h 37 min585 subs | 2 h 43 min976 subs |
About the Helix Nebula
The nearest bright planetary nebula, half the Moon's width but spread thin. Low from the UK; dual-band and a couple of hours make the eye appear.
NGC 7293, Caldwell 63 · Planetary nebula in Aquarius · magnitude 7.3 · 25′ × 22′ · best in Aug, Sep, Oct. 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 Helix 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
- Helix Nebula with the ZWO Seestar S50 Pro: 2 h 15 min from Bortle 6
- Helix Nebula with the ZWO Seestar S30: 2 h 20 min from Bortle 6
- Helix Nebula with the ZWO Seestar S30 Pro: 2 h 25 min from Bortle 6
- Helix Nebula with the DwarfLab DWARF 3: 2 h 28 min from Bortle 6
- Helix Nebula with the DwarfLab DWARF mini: 1 h 58 min from Bortle 6
- Helix Nebula with the DwarfLab Draco: 1 h 35 min from Bortle 6
- Helix Nebula with the DwarfLab DWARF II: 11 h from Bortle 6
- Helix Nebula with the Vaonis Vespera II: 3 h 13 min from Bortle 6
- Helix Nebula with the Vaonis Vespera Pro: 7 h 14 min from Bortle 6
- Helix Nebula with the Vaonis Vespera 3: 3 h 05 min from Bortle 6
- Helix Nebula with the Vaonis Vespera Pro 2: 6 h 53 min from Bortle 6
- Helix Nebula with the Unistellar eQuinox 2: 2 h 57 min from Bortle 6
- Helix Nebula with the Unistellar Odyssey: 14 h from Bortle 6
- Helix Nebula with the Celestron Origin: 51 min from Bortle 6
- Helix Nebula with the Celestron Origin Mark II: 1 h 10 min from Bortle 6
All telescopes for the Helix Nebula · All targets for the Seestar S50