How long to image the Helix Nebula with the ZWO Seestar S50 Pro
From a Bortle 6 suburban sky, the ZWO Seestar S50 Pro needs about 2 h 15 min (808 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 34 min; a showpiece 8 h 58 min. Under a Bortle 3 rural sky the solid figure drops to 1 h 34 min. At Bortle 6 the limit is a mix of skyglow and read noise. In this scope's field it fills 30% 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 | 23 min136 subs | 1 h 30 min542 subs | 6 h 01 min2,166 subs |
| Bortle 2Typical dark site | 23 min138 subs | 1 h 32 min550 subs | 6 h 06 min2,199 subs |
| Bortle 3Rural | 24 min142 subs | 1 h 34 min566 subs | 6 h 17 min2,261 subs |
| Bortle 4Rural / suburban transition | 25 min151 subs | 1 h 40 min603 subs | 6 h 42 min2,411 subs |
| Bortle 5Suburban | 28 min166 subs | 1 h 50 min662 subs | 7 h 21 min2,648 subs |
| Bortle 6Bright suburban | 34 min202 subs | 2 h 15 min808 subs | 8 h 58 min3,231 subs |
| Bortle 7Suburban / urban transition | 45 min272 subs | 3 h 01 min1,086 subs | 12 h4,341 subs |
| Bortle 8City | 1 h 03 min380 subs | 4 h 13 min1,517 subs | 17 h6,065 subs |
| Bortle 9Inner city | 1 h 41 min609 subs | 6 h 46 min2,436 subs | 27 h9,741 subs |
Power and kit for this session
Allowing for slewing, focusing and rejected subs, that is about 2 h 55 min of run time. The Seestar S50 Pro’s battery (rated about 9 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 30WAccepts 12 V 3 A PD, so a 30 W bank tops up the 10,000 mAh cell while imaging.
- Seestar S50 Pro dew shieldDew heater is built in; a shield adds margin on damp nights. Check the listing says S50 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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Everything that fits the Seestar S50 Pro →
How it frames
The Helix Nebula is 25′ × 22′ across. The Seestar S50 Pro frames 2.45° × 1.38° at 2.30″ per pixel, so it fills 30% of the frame’s short side.
Longer subs
10, 20 and 30 s in Alt-Az; 60 s only in EQ mode, and 60 s is the ceiling. Time for a solid image by sub length:
| Sub length | Bortle 3 | Bortle 5 | Bortle 7 |
|---|---|---|---|
| 10 s | 1 h 34 min566 subs | 1 h 50 min662 subs | 3 h 01 min1,086 subs |
| 20 s | 1 h 07 min201 subs | 1 h 23 min250 subs | 2 h 34 min461 subs |
| 30 s | 58 min116 subs | 1 h 14 min148 subs | 2 h 25 min290 subs |
| 60 s | 49 min49 subs | 1 h 05 min65 subs | 2 h 15 min136 subs |
With and without the dual-band filter
| Filter | Bortle 3 | Bortle 5 | Bortle 7 |
|---|---|---|---|
| UV/IR-cut (no light-pollution filter) | 1 h 20 min478 subs | 2 h 12 min794 subs | 6 h 03 min2,177 subs |
| dual-band (LP filter) | 1 h 34 min566 subs | 1 h 50 min662 subs | 3 h 01 min1,086 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 Pro
The S50 optics at 260 mm on an 8 MP 1/1.2-inch sensor: a wider, taller field, four times the pixels, and 60 s subs in EQ mode. Per pixel it is a whisker slower than the S50 because of the longer focal length; the long subs make it the better dark-site scope.
10, 20 and 30 s in Alt-Az; 60 s only in EQ mode, and 60 s is the ceiling. Built-in UV/IR-cut, dual-band (OIII 30 nm / Hα 20 nm) and dark filters on the telephoto camera.
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 Pro? 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: 2 h 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 Pro