How long to image the Cocoon Nebula with the ZWO Seestar S30 Pro
From a Bortle 6 suburban sky, the ZWO Seestar S30 Pro needs about 3 h 36 min (1,294 subs of 10 s with the built-in dual-band (LP filter) filter) for a solid image of the Cocoon Nebula. A quick look takes 54 min; a showpiece 14 h. Under a Bortle 3 rural sky the solid figure drops to 2 h 32 min. At Bortle 6 the limit is a mix of skyglow and read noise. In this scope's field it fills 9% 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 | 36 min219 subs | 2 h 26 min874 subs | 9 h 42 min3,493 subs |
| Bortle 2Typical dark site | 37 min222 subs | 2 h 28 min887 subs | 9 h 51 min3,545 subs |
| Bortle 3Rural | 38 min228 subs | 2 h 32 min911 subs | 10 h3,643 subs |
| Bortle 4Rural / suburban transition | 40 min243 subs | 2 h 42 min970 subs | 11 h3,879 subs |
| Bortle 5Suburban | 44 min266 subs | 2 h 57 min1,064 subs | 12 h4,255 subs |
| Bortle 6Bright suburban | 54 min324 subs | 3 h 36 min1,294 subs | 14 h5,176 subs |
| Bortle 7Suburban / urban transition | 1 h 12 min434 subs | 4 h 49 min1,733 subs | 19 h6,931 subs |
| Bortle 8City | 1 h 41 min604 subs | 6 h 42 min2,414 subs | 27 h9,656 subs |
| Bortle 9Inner city | 2 h 41 min967 subs | 11 h3,867 subs | 43 h15,468 subs |
Power and kit for this session
Allowing for slewing, focusing and rejected subs, that is about 4 h 40 min of run time. The Seestar S30 Pro’s battery is rated at about 5 h, which is cutting it fine; take a power bank. (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 Cocoon Nebula is 12′ across. The Seestar S30 Pro frames 3.99° × 2.24° at 3.74″ per pixel, so it fills 9% 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 | 2 h 32 min911 subs | 2 h 57 min1,064 subs | 4 h 49 min1,733 subs |
| 20 s | 1 h 46 min320 subs | 2 h 12 min396 subs | 4 h 03 min731 subs |
| 30 s | 1 h 31 min183 subs | 1 h 57 min234 subs | 3 h 48 min457 subs |
| 60 s | 1 h 16 min77 subs | 1 h 42 min102 subs | 3 h 33 min214 subs |
With and without the dual-band filter
| Filter | Bortle 3 | Bortle 5 | Bortle 7 |
|---|---|---|---|
| UV/IR-cut (no light-pollution filter) | 2 h 07 min761 subs | 3 h 30 min1,261 subs | 9 h 34 min3,446 subs |
| dual-band (LP filter) | 2 h 32 min911 subs | 2 h 57 min1,064 subs | 4 h 49 min1,733 subs |
About the Cocoon Nebula
A round emission and reflection nebula at the end of a long dark lane. Mixed light, so a broadband stack keeps the blue.
IC 5146, Caldwell 19 · Emission nebula in Cygnus · magnitude 7.2 · 12′ · best in Jul, Aug, Sep. 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 Cocoon 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
- Cocoon Nebula with the ZWO Seestar S50: 2 h 58 min from Bortle 6
- Cocoon Nebula with the ZWO Seestar S50 Pro: 3 h 20 min from Bortle 6
- Cocoon Nebula with the ZWO Seestar S30: 3 h 29 min from Bortle 6
- Cocoon Nebula with the DwarfLab DWARF 3: 3 h 39 min from Bortle 6
- Cocoon Nebula with the DwarfLab DWARF mini: 2 h 55 min from Bortle 6
- Cocoon Nebula with the DwarfLab Draco: 2 h 21 min from Bortle 6
- Cocoon Nebula with the DwarfLab DWARF II: 17 h from Bortle 6
- Cocoon Nebula with the Vaonis Vespera II: 4 h 49 min from Bortle 6
- Cocoon Nebula with the Vaonis Vespera Pro: 11 h from Bortle 6
- Cocoon Nebula with the Vaonis Vespera 3: 4 h 36 min from Bortle 6
- Cocoon Nebula with the Vaonis Vespera Pro 2: 10 h from Bortle 6
- Cocoon Nebula with the Unistellar eQuinox 2: 4 h 25 min from Bortle 6
- Cocoon Nebula with the Unistellar Odyssey: 21 h from Bortle 6
- Cocoon Nebula with the Celestron Origin: 1 h 16 min from Bortle 6
- Cocoon Nebula with the Celestron Origin Mark II: 1 h 44 min from Bortle 6
All telescopes for the Cocoon Nebula · All targets for the Seestar S30 Pro