Is the Seestar S50 faster than the Vespera II?

From a Bortle 6 sky the Seestar S50 is 1.3× faster on the 30 most popular deep-sky targets; from Bortle 3 the Vespera II is 1.1× faster.

Which is better for small targets like planetary nebulae?

Neither has a meaningful advantage; their pixel scales are similar.

Seestar S50 vs Vespera II: which is faster for deep-sky imaging?

ZWO Seestar S50 against Vaonis Vespera II, 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, the Seestar S50 is 1.3× faster (geometric mean of the solid-image times, each scope on its recommended filter and default subs). From a rural Bortle 3 sky the Vespera II is 1.1× faster, so the ranking flips under dark skies.

Field of view. The Vespera II shows 2.55° × 1.44° against 1.28° × 0.72°, so big targets such as the Andromeda Galaxy, the North America Nebula and the Pleiades fit with room to spare where the Seestar S50 needs a mosaic or a tight crop.

Detail. Pixel scales are within 10% of each other, so neither has a real detail advantage.

Subs and dark skies. The Seestar S50 goes up to 60 s subs in EQ mode, the Vespera II tops out at 30 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 has a dual-band filter built in; the Vespera II does not, which costs it heavily on emission nebulae from any suburban sky.

Specifications side by side

Spec	Seestar S50	Vespera II
Aperture	50 mm	50 mm
Focal length	250 mm (f/5.0)	250 mm (f/5.0)
Sensor	Sony IMX462, 2.1 MP	Sony IMX585, 8.3 MP
Pixel size	2.9 µm	2.9 µm
Pixel scale	2.39″/px	2.39″/px
Field of view	1.28° × 0.72°	2.55° × 1.44°
Sub exposures	10 s, 20 s, 30 s, 60 s	10 s, 20 s, 30 s
Dual-band filter	Built in (LP filter)	Clip-on option (Dual Band filter)
“No filter” position	UV/IR-cut	No filter
Read noise used	1 e⁻	1 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	Vespera II	Faster
Andromeda GalaxyGalaxy	1 h 27 min525 subs	1 h 27 min525 subs	Same
Orion NebulaEmission nebula	12 min75 subs	17 min103 subs	Seestar S50 1.4×
North America NebulaEmission nebula	1 h 25 min512 subs	2 h 15 min813 subs	Seestar S50 1.6×
Pinwheel GalaxyGalaxy	4 h 37 min1,661 subs	4 h 37 min1,661 subs	Same
Ring NebulaPlanetary nebula	7 min42 subs	8 min47 subs	Seestar S50 1.1×
Western Veil NebulaSupernova remnant	1 h 33 min557 subs	2 h 28 min889 subs	Seestar S50 1.6×
Hercules ClusterGlobular cluster	7 min44 subs	7 min44 subs	Same
PleiadesReflection nebula	2 h 42 min971 subs	2 h 42 min971 subs	Same

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	Vespera II	Faster
Andromeda GalaxyGalaxy	34 min204 subs	34 min204 subs	Same
Orion NebulaEmission nebula	10 min58 subs	8 min47 subs	Vespera II 1.2×
North America NebulaEmission nebula	59 min357 subs	51 min306 subs	Vespera II 1.2×
Pinwheel GalaxyGalaxy	1 h 40 min602 subs	1 h 40 min602 subs	Same
Ring NebulaPlanetary nebula	6 min36 subs	5 min30 subs	Vespera II 1.2×
Western Veil NebulaSupernova remnant	1 h 04 min387 subs	55 min333 subs	Vespera II 1.2×
Hercules ClusterGlobular cluster	5 min30 subs	5 min30 subs	Same
PleiadesReflection nebula	1 h362 subs	1 h362 subs	Same

Try the Seestar S50 in the calculator Try the Vespera II

About the ZWO Seestar S50

The scope that made smart astrophotography mainstream. 50 mm triplet, 2 MP sensor, dual-band filter on a wheel. Alt-Az stacking at 10 s, EQ mode unlocks 60 s. Out of production since 2026 and replaced by the S50 Pro, but there are a great many in use.

Where to buy the Seestar S50ZWO 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 Vaonis Vespera II

A 50 mm quadruplet on an 8 MP sensor with Vaonis’s mosaic mode for wide fields. Same optics class as the Seestar S50, four times the pixels.

Where to buy the Vespera IIVaonis store Direct Amazon UK Amazon USThe Vaonis 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.

Other comparisons

All comparisons · Buying guide · Seestar S50 page · Vespera II page