ZWO Seestar S50 Pro: how long to image deep-sky targets

The S50 optics at 260 mm on an 8 MP 1/1.2-inch sensor: a wider, taller field, four times the pixels, and 60 s subs in EQ mode. Per pixel it is a whisker slower than the S50 because of the longer focal length; the long subs make it the better dark-site scope.

Spec	Value
Aperture	50 mm
Focal length	260 mm (f/5.2)
Sensor	OmniVision OS08B10 (1/1.2″), 3840 × 2160, 2.9 µm pixels
Pixel scale	2.30″ per pixel
Field of view	2.45° × 1.38° (147′ × 83′)
Sub exposures	10 s, 20 s, 30 s, 60 s (default 10 s)
Filters	Built-in UV/IR-cut, dual-band (OIII 30 nm / Hα 20 nm) and dark filters on the telephoto camera. 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 used	1 e⁻

Where to buy the Seestar S50 ProZWO store Direct Amazon UK Amazon 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.
Target	Bortle 4	Bortle 6	Bortle 8
Andromeda GalaxyGalaxy	47 min281 subs	1 h 36 min575 subs	4 h 25 min1,590 subs
Orion NebulaEmission nebula, dual-band	11 min68 subs	14 min83 subs	23 min137 subs
PleiadesReflection nebula	1 h 24 min506 subs	2 h 57 min1,063 subs	8 h 18 min2,988 subs
Whirlpool GalaxyGalaxy	32 min195 subs	1 h 04 min384 subs	2 h 53 min1,037 subs
Bode's GalaxyGalaxy	35 min208 subs	1 h 10 min419 subs	3 h 11 min1,147 subs
Pinwheel GalaxyGalaxy	2 h 21 min849 subs	5 h 03 min1,817 subs	14 h5,163 subs
Hercules ClusterGlobular cluster	5 min30 subs	8 min48 subs	19 min116 subs
Dumbbell NebulaPlanetary nebula, dual-band	18 min110 subs	22 min134 subs	36 min218 subs
Ring NebulaPlanetary nebula, dual-band	7 min41 subs	8 min46 subs	11 min65 subs
Lagoon NebulaEmission nebula, dual-band	17 min105 subs	22 min132 subs	37 min225 subs
Eagle NebulaEmission nebula, dual-band	52 min312 subs	1 h 08 min410 subs	2 h 05 min749 subs
Omega NebulaEmission nebula, dual-band	20 min123 subs	26 min154 subs	43 min260 subs
Trifid NebulaEmission nebula, dual-band	38 min227 subs	49 min294 subs	1 h 28 min529 subs
Triangulum GalaxyGalaxy	1 h 24 min506 subs	2 h 57 min1,063 subs	8 h 18 min2,988 subs
North America NebulaEmission nebula, dual-band	1 h 12 min433 subs	1 h 36 min574 subs	2 h 57 min1,065 subs
Western Veil NebulaSupernova remnant, dual-band	1 h 18 min470 subs	1 h 44 min625 subs	3 h 14 min1,163 subs
Eastern Veil NebulaSupernova remnant, dual-band	1 h 06 min398 subs	1 h 28 min528 subs	2 h 42 min975 subs
Elephant's Trunk NebulaEmission nebula, dual-band	1 h 59 min713 subs	2 h 40 min960 subs	5 h 02 min1,812 subs
Iris NebulaReflection nebula	1 h360 subs	2 h 04 min745 subs	5 h 46 min2,077 subs
Pacman NebulaEmission nebula, dual-band	1 h 25 min510 subs	1 h 53 min681 subs	3 h 32 min1,270 subs
Heart NebulaEmission nebula, dual-band	2 h 21 min845 subs	3 h 10 min1,141 subs	6 h 01 min2,166 subs
Rosette NebulaEmission nebula, dual-band	1 h 12 min433 subs	1 h 36 min574 subs	2 h 57 min1,065 subs
Horsehead NebulaEmission nebula, dual-band	1 h 40 min603 subs	2 h 15 min808 subs	4 h 13 min1,517 subs
Flame NebulaEmission nebula, dual-band	28 min166 subs	35 min213 subs	1 h 02 min375 subs
California NebulaEmission nebula, dual-band	1 h 40 min603 subs	2 h 15 min808 subs	4 h 13 min1,517 subs
Helix NebulaPlanetary nebula, dual-band	1 h 40 min603 subs	2 h 15 min808 subs	4 h 13 min1,517 subs
Double ClusterOpen cluster	5 min30 subs	5 min30 subs	6 min37 subs
NGC 891Galaxy	1 h 26 min515 subs	3 h1,079 subs	8 h 24 min3,026 subs
Sombrero GalaxyGalaxy	27 min162 subs	51 min309 subs	2 h 16 min817 subs
Sunflower GalaxyGalaxy	53 min318 subs	1 h 48 min649 subs	4 h 59 min1,793 subs

All 170 targets have a page for the Seestar S50 Pro.

Every target for the Seestar S50 Pro

Supernova remnants

Globular clusters

M2
M3
M4
M5
M9
M10
M12
Hercules Cluster
M14
M15
M19
M22
M28
M30
M53
M54
M55
M56
M62
M68
M69
M70
M71
M72
M75
M79
M80
M92
M107
Omega Centauri
47 Tucanae

Open clusters

Emission nebulas

Star clouds

Sagittarius Star Cloud

Planetary nebulas

Galaxies

Reflection nebulas

Getting the most from the Seestar S50 Pro

10, 20 and 30 s in Alt-Az; 60 s only in EQ mode, and 60 s is the ceiling. 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.

Compare the Seestar S50 Pro

Useful gear

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

ZWO Seestar TH10 fluid tripod head quick release plateZWO's EQ head; the 3/8-inch quick-release plate is the S50 Pro-specific fitting.
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USB-C PD power bank 20000mAh 30WAccepts 12 V 3 A PD, so a 30 W bank tops up the 10,000 mAh cell while imaging.
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ZWO TC20 carbon fiber tripod SeestarZWO's recommended tripod for EQ mode; the boxed one is fine for Alt-Az.
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Seestar S50 Pro dew shieldDew heater is built in; a shield adds margin on damp nights. Check the listing says S50 Pro.
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All Seestar S50 Pro accessories, and what to take on a cold night →