How long to image the California Nebula with the ZWO Seestar S30 Pro
From a Bortle 6 suburban sky, the ZWO Seestar S30 Pro needs about 2 h 25 min (872 subs of 10 s with the built-in dual-band (LP filter) filter) for a solid image of the California Nebula. A quick look takes 36 min; a showpiece 9 h 41 min. Under a Bortle 3 rural sky the solid figure drops to 1 h 43 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 1.2×.
| Sky | Quick lookTarget obvious, still noisy | SolidClean enough to share | ShowpieceSmooth faint detail, print-worthy |
|---|---|---|---|
| Bortle 1Excellent dark site | 25 min148 subs | 1 h 39 min592 subs | 6 h 34 min2,365 subs |
| Bortle 2Typical dark site | 25 min150 subs | 1 h 40 min600 subs | 6 h 40 min2,399 subs |
| Bortle 3Rural | 26 min154 subs | 1 h 43 min616 subs | 6 h 51 min2,464 subs |
| Bortle 4Rural / suburban transition | 27 min164 subs | 1 h 49 min656 subs | 7 h 17 min2,622 subs |
| Bortle 5Suburban | 30 min180 subs | 2 h718 subs | 7 h 59 min2,872 subs |
| Bortle 6Bright suburban | 36 min218 subs | 2 h 25 min872 subs | 9 h 41 min3,485 subs |
| Bortle 7Suburban / urban transition | 48 min291 subs | 3 h 14 min1,163 subs | 13 h4,652 subs |
| Bortle 8City | 1 h 07 min405 subs | 4 h 29 min1,617 subs | 18 h6,466 subs |
| Bortle 9Inner city | 1 h 48 min646 subs | 7 h 11 min2,584 subs | 29 h10,333 subs |
Power and kit for this session
Allowing for slewing, focusing and rejected subs, that is about 3 h 09 min of run time. The Seestar S30 Pro’s battery is rated at about 5 h, less near freezing, which is cutting it fine; take a power bank. (Bortle 6, solid image; we allow 30% over the integration time, and 30% off the battery for a December night.)
- 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.
- 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 California Nebula is 160′ × 40′ across. The Seestar S30 Pro frames 3.99° × 2.24° at 3.74″ per pixel, so it is just over the frame at 1.2×. 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, which needs the TH10 head. Time for a solid image by sub length:
| Sub length | Bortle 3 | Bortle 5 | Bortle 7 |
|---|---|---|---|
| 10 s | 1 h 43 min616 subs | 2 h718 subs | 3 h 14 min1,163 subs |
| 20 s | 1 h 12 min218 subs | 1 h 29 min269 subs | 2 h 44 min491 subs |
| 30 s | 1 h 02 min125 subs | 1 h 19 min159 subs | 2 h 34 min308 subs |
| 60 s | 52 min53 subs | 1 h 09 min70 subs | 2 h 24 min144 subs |
With and without the dual-band filter
| Filter | Bortle 3 | Bortle 5 | Bortle 7 |
|---|---|---|---|
| UV/IR-cut (no light-pollution filter) | 1 h 25 min513 subs | 2 h 21 min846 subs | 6 h 23 min2,300 subs |
| dual-band (LP filter) | 1 h 43 min616 subs | 2 h718 subs | 3 h 14 min1,163 subs |
About the California Nebula
A long, faint hydrogen streak near Menkib, nearly three degrees end to end. Needs a wide field and a dual-band filter; it is almost invisible in broadband.
NGC 1499 · Emission nebula in Perseus · magnitude 6.0 · 160′ × 40′ · 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 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 California 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
- California Nebula with the ZWO Seestar S50: 2 h from Bortle 6
- California Nebula with the ZWO Seestar S50 Pro: 2 h 15 min from Bortle 6
- California Nebula with the ZWO Seestar S30: 2 h 20 min from Bortle 6
- California Nebula with the DwarfLab DWARF 3: 2 h 28 min from Bortle 6
- California Nebula with the DwarfLab DWARF mini: 1 h 58 min from Bortle 6
- California Nebula with the DwarfLab Draco: 1 h 35 min from Bortle 6
- California Nebula with the DwarfLab DWARF II: 11 h from Bortle 6
- California Nebula with the Vaonis Vespera II: 3 h 13 min from Bortle 6
- California Nebula with the Vaonis Vespera Pro: 7 h 14 min from Bortle 6
- California Nebula with the Vaonis Vespera 3: 3 h 05 min from Bortle 6
- California Nebula with the Vaonis Vespera Pro 2: 6 h 53 min from Bortle 6
- California Nebula with the Unistellar eQuinox 2: 2 h 57 min from Bortle 6
- California Nebula with the Unistellar Odyssey: 14 h from Bortle 6
- California Nebula with the Celestron Origin: 51 min from Bortle 6
- California Nebula with the Celestron Origin Mark II: 1 h 10 min from Bortle 6
All telescopes for the California Nebula · All targets for the Seestar S30 Pro