How long to image the Owl Nebula with the ZWO Seestar S50 Pro
From a Bortle 6 suburban sky, the ZWO Seestar S50 Pro needs about 42 min (254 subs of 10 s with the built-in dual-band (LP filter) filter) for a solid image of the Owl Nebula. A quick look takes 11 min; a showpiece 2 h 49 min. Under a Bortle 3 rural sky the solid figure drops to 32 min. At Bortle 6 the limit is a mix of skyglow and read noise. In this scope's field it fills 4% 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 | 8 min47 subs | 31 min188 subs | 2 h 05 min751 subs |
| Bortle 2Typical dark site | 8 min48 subs | 32 min190 subs | 2 h 06 min759 subs |
| Bortle 3Rural | 8 min49 subs | 32 min194 subs | 2 h 09 min774 subs |
| Bortle 4Rural / suburban transition | 8 min51 subs | 34 min203 subs | 2 h 15 min811 subs |
| Bortle 5Suburban | 9 min55 subs | 36 min218 subs | 2 h 25 min870 subs |
| Bortle 6Bright suburban | 11 min64 subs | 42 min254 subs | 2 h 49 min1,014 subs |
| Bortle 7Suburban / urban transition | 13 min81 subs | 54 min322 subs | 3 h 35 min1,288 subs |
| Bortle 8City | 18 min108 subs | 1 h 11 min429 subs | 4 h 45 min1,713 subs |
| Bortle 9Inner city | 27 min164 subs | 1 h 49 min655 subs | 7 h 17 min2,620 subs |
Power and kit for this session
Allowing for slewing, focusing and rejected subs, that is about 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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How it frames
The Owl Nebula is 3.4′ × 3.3′ across. The Seestar S50 Pro frames 2.45° × 1.38° at 2.30″ per pixel, so it fills 4% 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 | 32 min194 subs | 36 min218 subs | 54 min322 subs |
| 20 s | 26 min77 subs | 30 min89 subs | 47 min141 subs |
| 30 s | 23 min47 subs | 27 min55 subs | 45 min90 subs |
| 60 s | 30 min30 subs | 30 min30 subs | 42 min43 subs |
With and without the dual-band filter
| Filter | Bortle 3 | Bortle 5 | Bortle 7 |
|---|---|---|---|
| UV/IR-cut (no light-pollution filter) | 26 min156 subs | 39 min234 subs | 1 h 36 min575 subs |
| dual-band (LP filter) | 32 min194 subs | 36 min218 subs | 54 min322 subs |
About the Owl Nebula
A round planetary with two dark eyes. Large for its class and low in surface brightness; dual-band helps a lot.
M97, NGC 3587 · Planetary nebula in Ursa Major · magnitude 9.9 · 3.4′ × 3.3′ · best in Feb, Mar, Apr. 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 Owl 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
- Owl Nebula with the ZWO Seestar S50: 38 min from Bortle 6
- Owl Nebula with the ZWO Seestar S30: 43 min from Bortle 6
- Owl Nebula with the ZWO Seestar S30 Pro: 45 min from Bortle 6
- Owl Nebula with the DwarfLab DWARF 3: 49 min from Bortle 6
- Owl Nebula with the DwarfLab DWARF mini: 37 min from Bortle 6
- Owl Nebula with the DwarfLab Draco: 30 min from Bortle 6
- Owl Nebula with the DwarfLab DWARF II: 3 h from Bortle 6
- Owl Nebula with the Vaonis Vespera II: 54 min from Bortle 6
- Owl Nebula with the Vaonis Vespera Pro: 1 h 59 min from Bortle 6
- Owl Nebula with the Vaonis Vespera 3: 51 min from Bortle 6
- Owl Nebula with the Vaonis Vespera Pro 2: 1 h 54 min from Bortle 6
- Owl Nebula with the Unistellar eQuinox 2: 47 min from Bortle 6
- Owl Nebula with the Unistellar Odyssey: 3 h 36 min from Bortle 6
- Owl Nebula with the Celestron Origin: 14 min from Bortle 6
- Owl Nebula with the Celestron Origin Mark II: 20 min from Bortle 6
All telescopes for the Owl Nebula · All targets for the Seestar S50 Pro