How long to image the Orion Nebula with the ZWO Seestar S50 Pro
From a Bortle 6 suburban sky, the ZWO Seestar S50 Pro needs about 14 min (83 subs of 10 s with the built-in dual-band (LP filter) filter) for a solid image of the Orion Nebula. A quick look takes 3 min; a showpiece 55 min. Under a Bortle 3 rural sky the solid figure drops to 11 min. At Bortle 6 the limit is a mix of skyglow and read noise. In this scope's field it is just over the frame at 1.0×.
| Sky | Quick lookTarget obvious, still noisy | SolidClean enough to share | ShowpieceSmooth faint detail, print-worthy |
|---|---|---|---|
| Bortle 1Excellent dark site | 3 min16 subs | 10 min63 subs | 42 min251 subs |
| Bortle 2Typical dark site | 3 min16 subs | 11 min64 subs | 42 min254 subs |
| Bortle 3Rural | 3 min17 subs | 11 min65 subs | 43 min259 subs |
| Bortle 4Rural / suburban transition | 3 min17 subs | 11 min68 subs | 45 min270 subs |
| Bortle 5Suburban | 3 min18 subs | 12 min72 subs | 48 min288 subs |
| Bortle 6Bright suburban | 3 min21 subs | 14 min83 subs | 55 min332 subs |
| Bortle 7Suburban / urban transition | 4 min26 subs | 17 min104 subs | 1 h 09 min416 subs |
| Bortle 8City | 6 min35 subs | 23 min137 subs | 1 h 31 min547 subs |
| Bortle 9Inner city | 9 min52 subs | 34 min207 subs | 2 h 18 min826 subs |
Power and kit for this session
Allowing for slewing, focusing and rejected subs, that is about 18 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, and 30% off the battery for a December night.)
- 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.
- hand warmers long lastingAir-activated packs give hours of heat for the person; winter nights are long and you spend most of them standing still.
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How it frames
The Orion Nebula is 85′ × 60′ across. The Seestar S50 Pro frames 2.45° × 1.38° at 2.30″ per pixel, so it is just over the frame at 1.0×. Point at the part you want; the edges will fall outside the frame.
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 | 11 min65 subs | 12 min72 subs | 17 min104 subs |
| 20 s | 10 min30 subs | 10 min30 subs | 15 min46 subs |
| 30 s | 15 min30 subs | 15 min30 subs | 15 min30 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) | 9 min52 subs | 13 min76 subs | 30 min181 subs |
| dual-band (LP filter) | 11 min65 subs | 12 min72 subs | 17 min104 subs |
About the Orion Nebula
The brightest nebula in the northern sky and the one every smart scope gets pointed at first. The core saturates in a minute; the wings and the Running Man need real time. Mix short and long stacks.
M42, NGC 1976 · Emission nebula in Orion · magnitude 4.0 · 85′ × 60′ · best in Nov, Dec, Jan. Reachable from mid-northern latitudes (UK, northern US, central Europe) and from the south.
Emission nebulae glow in a few narrow lines, mostly hydrogen-alpha (deep red) and doubly ionised oxygen (teal). A dual-band filter passes those lines and blocks most skyglow, which is why it cuts the time needed from a suburban sky so dramatically. Use it. From a genuinely dark site the gain is smaller because there is less skyglow to block, and read noise becomes the limit, which is where longer subs (EQ mode, or Expert Mode on a Vespera) earn their keep.
Stars lose colour through a dual-band filter; a short broadband stack blended in fixes that if you care.
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 Orion 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
- Orion Nebula with the ZWO Seestar S50: 12 min from Bortle 6
- Orion Nebula with the ZWO Seestar S30: 14 min from Bortle 6
- Orion Nebula with the ZWO Seestar S30 Pro: 15 min from Bortle 6
- Orion Nebula with the DwarfLab DWARF 3: 16 min from Bortle 6
- Orion Nebula with the DwarfLab DWARF mini: 12 min from Bortle 6
- Orion Nebula with the DwarfLab Draco: 15 min from Bortle 6
- Orion Nebula with the DwarfLab DWARF II: 57 min from Bortle 6
- Orion Nebula with the Vaonis Vespera II: 17 min from Bortle 6
- Orion Nebula with the Vaonis Vespera Pro: 38 min from Bortle 6
- Orion Nebula with the Vaonis Vespera 3: 16 min from Bortle 6
- Orion Nebula with the Vaonis Vespera Pro 2: 36 min from Bortle 6
- Orion Nebula with the Unistellar eQuinox 2: 15 min from Bortle 6
- Orion Nebula with the Unistellar Odyssey: 1 h 08 min from Bortle 6
- Orion Nebula with the Celestron Origin: 5 min from Bortle 6
- Orion Nebula with the Celestron Origin Mark II: 6 min from Bortle 6
All telescopes for the Orion Nebula · All targets for the Seestar S50 Pro