How long to image the Trifid Nebula with the ZWO Seestar S30 Pro
From a Bortle 6 suburban sky, the ZWO Seestar S30 Pro needs about 53 min (317 subs of 10 s with the built-in dual-band (LP filter) filter) for a solid image of the Trifid Nebula. A quick look takes 13 min; a showpiece 3 h 31 min. Under a Bortle 3 rural sky the solid figure drops to 39 min. At Bortle 6 the limit is a mix of skyglow and read noise. In this scope's field it fills 21% 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 | 9 min56 subs | 37 min224 subs | 2 h 29 min895 subs |
| Bortle 2Typical dark site | 9 min57 subs | 38 min227 subs | 2 h 31 min906 subs |
| Bortle 3Rural | 10 min58 subs | 39 min232 subs | 2 h 35 min928 subs |
| Bortle 4Rural / suburban transition | 10 min62 subs | 41 min245 subs | 2 h 43 min980 subs |
| Bortle 5Suburban | 11 min67 subs | 44 min266 subs | 2 h 57 min1,063 subs |
| Bortle 6Bright suburban | 13 min80 subs | 53 min317 subs | 3 h 31 min1,266 subs |
| Bortle 7Suburban / urban transition | 17 min104 subs | 1 h 09 min413 subs | 4 h 35 min1,652 subs |
| Bortle 8City | 23 min141 subs | 1 h 34 min564 subs | 6 h 15 min2,253 subs |
| Bortle 9Inner city | 37 min221 subs | 2 h 27 min884 subs | 9 h 49 min3,534 subs |
Power and kit for this session
Allowing for slewing, focusing and rejected subs, that is about 1 h 09 min of run time. The Seestar S30 Pro’s battery (rated about 5 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 3A5 V 3 A input and it runs while charging.
- Seestar S30 Pro dew shieldActive anti-dew is built in; a shield adds margin. The S30 Pro front differs from the S30, so check the listing.
- 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 S30 Pro →
How it frames
The Trifid Nebula is 28′ across. The Seestar S30 Pro frames 3.99° × 2.24° at 3.74″ per pixel, so it fills 21% of the frame’s short side.
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 | 39 min232 subs | 44 min266 subs | 1 h 09 min413 subs |
| 20 s | 29 min86 subs | 34 min103 subs | 59 min177 subs |
| 30 s | 25 min51 subs | 31 min62 subs | 56 min112 subs |
| 60 s | 30 min30 subs | 30 min30 subs | 52 min53 subs |
With and without the dual-band filter
| Filter | Bortle 3 | Bortle 5 | Bortle 7 |
|---|---|---|---|
| UV/IR-cut (no light-pollution filter) | 32 min190 subs | 50 min300 subs | 2 h 10 min782 subs |
| dual-band (LP filter) | 39 min232 subs | 44 min266 subs | 1 h 09 min413 subs |
About the Trifid Nebula
Red emission, blue reflection and dark lanes in one object. Shoot it without a filter to keep the blue, or dual-band for the red.
M20, NGC 6514 · Emission nebula in Sagittarius · magnitude 6.3 · 28′ · best in Jun, Jul, Aug. 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 S30 Pro
The S30 optics upgraded to a quadruplet in front of an 8 MP IMX585. Same speed per pixel as the S30, four times the pixels, so you can crop hard.
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 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 Trifid Nebula from a Seestar S30 Pro? Email it with your total time and sky to [email protected] and it goes here, credited.
Same target, other telescopes
- Trifid Nebula with the ZWO Seestar S50: 44 min from Bortle 6
- Trifid Nebula with the ZWO Seestar S50 Pro: 49 min from Bortle 6
- Trifid Nebula with the ZWO Seestar S30: 51 min from Bortle 6
- Trifid Nebula with the DwarfLab DWARF 3: 55 min from Bortle 6
- Trifid Nebula with the DwarfLab DWARF mini: 43 min from Bortle 6
- Trifid Nebula with the DwarfLab Draco: 35 min from Bortle 6
- Trifid Nebula with the DwarfLab DWARF II: 3 h 48 min from Bortle 6
- Trifid Nebula with the Vaonis Vespera II: 1 h 07 min from Bortle 6
- Trifid Nebula with the Vaonis Vespera Pro: 2 h 30 min from Bortle 6
- Trifid Nebula with the Vaonis Vespera 3: 1 h 04 min from Bortle 6
- Trifid Nebula with the Vaonis Vespera Pro 2: 2 h 23 min from Bortle 6
- Trifid Nebula with the Unistellar eQuinox 2: 1 h from Bortle 6
- Trifid Nebula with the Unistellar Odyssey: 4 h 39 min from Bortle 6
- Trifid Nebula with the Celestron Origin: 18 min from Bortle 6
- Trifid Nebula with the Celestron Origin Mark II: 24 min from Bortle 6
All telescopes for the Trifid Nebula · All targets for the Seestar S30 Pro