How Many Subs

ZWO Seestar S30: how long to image deep-sky targets

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.

SpecValue
Aperture30 mm
Focal length150 mm (f/5.0)
SensorSony IMX662, 1920 × 1080, 2.9 µm pixels
Pixel scale3.99″ per pixel
Field of view2.13° × 1.20° (128′ × 72′)
Sub exposures10 s, 20 s, 30 s, 60 s (default 10 s)
FiltersBuilt-in UV/IR-cut, dual-band (OIII 30 nm / Hα 20 nm) and dark filters. What the names mean.
In the calculator“UV/IR-cut (no light-pollution filter)” is the UV/IR-cut position; “dual-band” is the built-in dual-band (LP filter).
Read noise used1.2 e⁻
Where to buy the Seestar S30ZWO store DirectAmazon UKAmazon USThe ZWO store link is a plain link; the others are affiliate links. As an Amazon Associate I earn from qualifying purchases, at no cost to you.

Weighing it against the others? The buying guide puts every scope on one table.

Popular targets

Total integration for a solid image, 10 s subs, recommended filter.
TargetBortle 4Bortle 6Bortle 8
Andromeda GalaxyGalaxy47 min280 subs1 h 32 min552 subs4 h 08 min1,491 subs
Orion NebulaEmission nebula, dual-band12 min70 subs14 min84 subs22 min134 subs
PleiadesReflection nebula1 h 24 min506 subs2 h 50 min1,022 subs7 h 47 min2,801 subs
Whirlpool GalaxyGalaxy32 min194 subs1 h 01 min369 subs2 h 42 min972 subs
Bode's GalaxyGalaxy34 min207 subs1 h 07 min402 subs2 h 59 min1,075 subs
Pinwheel GalaxyGalaxy2 h 22 min853 subs4 h 51 min1,748 subs13 h4,841 subs
Hercules ClusterGlobular cluster5 min30 subs8 min46 subs18 min109 subs
Dumbbell NebulaPlanetary nebula, dual-band19 min113 subs23 min136 subs35 min213 subs
Ring NebulaPlanetary nebula, dual-band7 min40 subs7 min45 subs10 min63 subs
Lagoon NebulaEmission nebula, dual-band18 min110 subs22 min135 subs37 min221 subs
Eagle NebulaEmission nebula, dual-band56 min334 subs1 h 11 min425 subs2 h 03 min739 subs
Omega NebulaEmission nebula, dual-band21 min128 subs26 min157 subs42 min255 subs
Trifid NebulaEmission nebula, dual-band40 min241 subs51 min304 subs1 h 27 min521 subs
Triangulum GalaxyGalaxy1 h 24 min506 subs2 h 50 min1,022 subs7 h 47 min2,801 subs
North America NebulaEmission nebula, dual-band1 h 18 min466 subs1 h 39 min597 subs2 h 55 min1,050 subs
Western Veil NebulaSupernova remnant, dual-band1 h 24 min507 subs1 h 48 min651 subs3 h 11 min1,148 subs
Eastern Veil NebulaSupernova remnant, dual-band1 h 11 min429 subs1 h 31 min548 subs2 h 40 min962 subs
Elephant's Trunk NebulaEmission nebula, dual-band2 h 09 min775 subs2 h 47 min1,003 subs4 h 58 min1,790 subs
Iris NebulaReflection nebula1 h359 subs1 h 59 min716 subs5 h 24 min1,947 subs
Pacman NebulaEmission nebula, dual-band1 h 32 min551 subs1 h 58 min709 subs3 h 29 min1,254 subs
Heart NebulaEmission nebula, dual-band2 h 33 min920 subs3 h 19 min1,194 subs5 h 57 min2,141 subs
Rosette NebulaEmission nebula, dual-band1 h 18 min466 subs1 h 39 min597 subs2 h 55 min1,050 subs
Horsehead NebulaEmission nebula, dual-band1 h 49 min653 subs2 h 20 min843 subs4 h 10 min1,498 subs
Flame NebulaEmission nebula, dual-band29 min175 subs36 min219 subs1 h 01 min369 subs
California NebulaEmission nebula, dual-band1 h 49 min653 subs2 h 20 min843 subs4 h 10 min1,498 subs
Helix NebulaPlanetary nebula, dual-band1 h 49 min653 subs2 h 20 min843 subs4 h 10 min1,498 subs
Double ClusterOpen cluster5 min30 subs5 min30 subs6 min34 subs
NGC 891Galaxy1 h 26 min516 subs2 h 53 min1,037 subs7 h 53 min2,838 subs
Sombrero GalaxyGalaxy27 min160 subs49 min296 subs2 h 08 min766 subs
Sunflower GalaxyGalaxy53 min317 subs1 h 44 min623 subs4 h 40 min1,681 subs

All 170 targets have a page for the Seestar S30.

Every target for the Seestar S30

Supernova remnants

Globular clusters

Open clusters

Emission nebulas

Star clouds

Planetary nebulas

Galaxies

Reflection nebulas

Getting the most from the Seestar S30

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.

Compare the Seestar S30

Useful gear

What actually fits this scope, checked against the maker's own pages: power, EQ mode, dew and carry.

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All Seestar S30 accessories, and what to take on a cold night →