How long to image the Owl Nebula with the ZWO Seestar S30
From a Bortle 6 suburban sky, the ZWO Seestar S30 needs about 43 min (258 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 52 min. Under a Bortle 3 rural sky the solid figure drops to 34 min. At Bortle 6 the limit is a mix of skyglow and read noise. In this scope's field it is small in the frame, about 51 pixels across.
| Sky | Quick lookTarget obvious, still noisy | SolidClean enough to share | ShowpieceSmooth faint detail, print-worthy |
|---|---|---|---|
| Bortle 1Excellent dark site | 8 min50 subs | 33 min198 subs | 2 h 11 min789 subs |
| Bortle 2Typical dark site | 8 min50 subs | 33 min199 subs | 2 h 13 min796 subs |
| Bortle 3Rural | 8 min51 subs | 34 min203 subs | 2 h 15 min810 subs |
| Bortle 4Rural / suburban transition | 9 min53 subs | 35 min212 subs | 2 h 21 min845 subs |
| Bortle 5Suburban | 9 min57 subs | 37 min225 subs | 2 h 30 min899 subs |
| Bortle 6Bright suburban | 11 min65 subs | 43 min258 subs | 2 h 52 min1,032 subs |
| Bortle 7Suburban / urban transition | 13 min81 subs | 54 min322 subs | 3 h 34 min1,285 subs |
| Bortle 8City | 17 min105 subs | 1 h 10 min420 subs | 4 h 40 min1,678 subs |
| Bortle 9Inner city | 26 min158 subs | 1 h 45 min630 subs | 6 h 59 min2,517 subs |
Power and kit for this session
Allowing for slewing, focusing and rejected subs, that is about 56 min of run time. The Seestar S30’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 10000mAh 5V 3A6,000 mAh inside; a 10,000 mAh 5 V 3 A bank roughly doubles a session.
- Seestar S30 dew shieldHeater is built in; a cheap shield reduces dew and 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 Owl Nebula is 3.4′ × 3.3′ across. The Seestar S30 frames 2.13° × 1.20° at 3.99″ per pixel, so it is small in the frame, about 51 pixels across. It is worth doing, but the result is a crop rather than a full frame; a longer focal length would resolve more of it.
Longer subs
10, 20 and 30 s in Alt-Az; 60 s only in EQ mode, which needs the TH10 head. Time for a solid image by sub length:
| Sub length | Bortle 3 | Bortle 5 | Bortle 7 |
|---|---|---|---|
| 10 s | 34 min203 subs | 37 min225 subs | 54 min322 subs |
| 20 s | 25 min77 subs | 29 min88 subs | 45 min136 subs |
| 30 s | 23 min46 subs | 26 min53 subs | 42 min85 subs |
| 60 s | 30 min30 subs | 30 min30 subs | 40 min40 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 | 38 min228 subs | 1 h 30 min543 subs |
| dual-band (LP filter) | 34 min203 subs | 37 min225 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 S30
Wider and lighter than the S50 with the same 2.9 µm pixels, so its per-pixel speed on extended targets is close despite the smaller aperture. Ideal for big nebulae.
10, 20 and 30 s in Alt-Az; 60 s only in EQ mode, which needs the TH10 head. Built-in UV/IR-cut, dual-band (OIII 30 nm / Hα 20 nm) and dark filters.
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 S30? 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 S50 Pro: 42 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 S30