Is the Seestar S50 Pro faster than the eQuinox 2?

From a Bortle 6 sky they are about the same speed on the 30 most popular deep-sky targets; from Bortle 3 they are about the same speed.

Which is better for small targets like planetary nebulae?

The eQuinox 2, with its finer pixel scale of 1.33″ per pixel.

Seestar S50 Pro vs eQuinox 2: which is faster for deep-sky imaging?

ZWO Seestar S50 Pro against Unistellar eQuinox 2, on the same targets from the same skies, using the same photon-budget model as the rest of the site. Times are for a solid image; the calculator gives quick-look and showpiece figures too.

Speed. Across the 30 most popular targets from a suburban Bortle 6 sky, they are about the same speed. From a rural Bortle 3 sky they are about the same speed.

Field of view. The Seestar S50 Pro shows 2.45° × 1.38° against 0.76° × 0.57°, so big targets such as the Andromeda Galaxy, the North America Nebula and the Pleiades fit with room to spare where the eQuinox 2 needs a mosaic or a tight crop.

Detail. The eQuinox 2 samples at 1.33″ per pixel against 2.30″, so it pulls finer structure from small targets: planetary nebulae, globular cores, galaxy arms.

Subs and dark skies. The Seestar S50 Pro goes up to 60 s subs in EQ mode, the eQuinox 2 tops out at 4 s. That matters little from a city, where skyglow sets the floor, and a lot from a dark site, where read noise does.

Filters. The Seestar S50 Pro has a dual-band filter built in; the eQuinox 2 does not, which costs it heavily on emission nebulae from any suburban sky.

Specifications side by side

Spec	Seestar S50 Pro	eQuinox 2
Aperture	50 mm	114 mm
Focal length	260 mm (f/5.2)	450 mm (f/3.9)
Sensor	OmniVision OS08B10 (1/1.2″), 8.3 MP	IMX347-class, 2.9 µm (Unistellar does not name it), 3.2 MP
Pixel size	2.9 µm	2.9 µm
Pixel scale	2.30″/px	1.33″/px
Field of view	2.45° × 1.38°	0.76° × 0.57°
Sub exposures	10 s, 20 s, 30 s, 60 s	4 s
Dual-band filter	Built in (LP filter)	None
“No filter” position	UV/IR-cut	No filter
Read noise used	1 e⁻	1.8 e⁻

Timed on the same targets

Suburban sky (Bortle 6)

Total integration for a solid image from a Bortle 6 sky, default subs, recommended filter for each scope.
Target	Seestar S50 Pro	eQuinox 2	Faster
Andromeda GalaxyGalaxy	1 h 36 min575 subs	1 h 19 min1,191 subs	eQuinox 2 1.2×
Orion NebulaEmission nebula	14 min83 subs	15 min224 subs	Seestar S50 Pro 1.1×
North America NebulaEmission nebula	1 h 36 min574 subs	2 h 04 min1,854 subs	Seestar S50 Pro 1.3×
Pinwheel GalaxyGalaxy	5 h 03 min1,817 subs	4 h 14 min3,814 subs	eQuinox 2 1.2×
Ring NebulaPlanetary nebula	8 min46 subs	6 min96 subs	eQuinox 2 1.2×
Western Veil NebulaSupernova remnant	1 h 44 min625 subs	2 h 15 min2,028 subs	Seestar S50 Pro 1.3×
Hercules ClusterGlobular cluster	8 min48 subs	6 min94 subs	eQuinox 2 1.3×
PleiadesReflection nebula	2 h 57 min1,063 subs	2 h 28 min2,219 subs	eQuinox 2 1.2×

Rural sky (Bortle 3)

Total integration for a solid image from a Bortle 3 sky, default subs, recommended filter for each scope.
Target	Seestar S50 Pro	eQuinox 2	Faster
Andromeda GalaxyGalaxy	38 min227 subs	46 min690 subs	Seestar S50 Pro 1.2×
Orion NebulaEmission nebula	11 min65 subs	9 min137 subs	eQuinox 2 1.2×
North America NebulaEmission nebula	1 h 08 min407 subs	1 h 11 min1,064 subs	Same
Pinwheel GalaxyGalaxy	1 h 52 min672 subs	2 h 24 min2,164 subs	Seestar S50 Pro 1.3×
Ring NebulaPlanetary nebula	7 min40 subs	4 min66 subs	eQuinox 2 1.5×
Western Veil NebulaSupernova remnant	1 h 13 min441 subs	1 h 17 min1,162 subs	Seestar S50 Pro 1.1×
Hercules ClusterGlobular cluster	5 min30 subs	4 min60 subs	eQuinox 2 1.3×
PleiadesReflection nebula	1 h 07 min404 subs	1 h 25 min1,270 subs	Seestar S50 Pro 1.3×

Try the Seestar S50 Pro in the calculator Try the eQuinox 2

About the ZWO Seestar S50 Pro

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.

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.

About the Unistellar eQuinox 2

A 114 mm Newtonian with five times the light grasp of a 50 mm refractor. Fixed 4 s subs put it in read-noise territory under dark skies, but the aperture carries it. The published field is 45.6′ × 34.2′, a crop of the sensor.

Where to buy the eQuinox 2Amazon UK Unistellar UK Amazon US Unistellar USAffiliate links: As an Amazon Associate I earn from qualifying purchases, at no cost to you.

Other comparisons

All comparisons · Buying guide · Seestar S50 Pro page · eQuinox 2 page