How long should I image the Pacman Nebula with the Seestar S50 from a Bortle 6 sky?

About 1 h 41 min of total integration for a solid image, or 6 h 44 min for a showpiece. A quick look takes 25 min.

How many subs is that on the Seestar S50?

At the default 10 s sub length, 607 subs for a solid image from Bortle 6 and 420 from Bortle 3.

Does a dual-band filter help on the Pacman Nebula?

Yes. It is an emission-line object; from Bortle 6 the filter cuts the solid-image time from 2 h 42 min to 1 h 41 min.

How long to image the Pacman Nebula with the ZWO Seestar S50

From a Bortle 6 suburban sky, the ZWO Seestar S50 needs about 1 h 41 min (607 subs of 10 s with the built-in dual-band (LP filter) filter) for a solid image of the Pacman Nebula. A quick look takes 25 min; a showpiece 6 h 44 min. Under a Bortle 3 rural sky the solid figure drops to 1 h 10 min. At Bortle 6 the limit is a mix of skyglow and read noise. In this scope's field it fills 81% of the frame’s short side.

Pacman Nebula with the ZWO Seestar S50: 10 s subs with the built-in dual-band (LP filter) filter.
Sky	Quick lookTarget obvious, still noisy	SolidClean enough to share	ShowpieceSmooth faint detail, print-worthy
Bortle 1Excellent dark site	17 min101 subs	1 h 07 min402 subs	4 h 28 min1,607 subs
Bortle 2Typical dark site	17 min102 subs	1 h 08 min408 subs	4 h 32 min1,632 subs
Bortle 3Rural	17 min105 subs	1 h 10 min420 subs	4 h 40 min1,680 subs
Bortle 4Rural / suburban transition	19 min113 subs	1 h 15 min449 subs	4 h 59 min1,795 subs
Bortle 5Suburban	21 min124 subs	1 h 22 min495 subs	5 h 30 min1,978 subs
Bortle 6Bright suburban	25 min152 subs	1 h 41 min607 subs	6 h 44 min2,426 subs
Bortle 7Suburban / urban transition	34 min205 subs	2 h 17 min820 subs	9 h 07 min3,280 subs
Bortle 8City	48 min288 subs	3 h 12 min1,152 subs	13 h4,605 subs
Bortle 9Inner city	1 h 17 min465 subs	5 h 10 min1,859 subs	21 h7,433 subs

Adjust in the calculator

Power and kit for this session

Allowing for slewing, focusing and rejected subs, that is about 2 h 11 min of run time. The Seestar S50’s battery (rated about 6 h) should cover it; a power bank still keeps the phone running the app alive. (Bortle 6, solid image; we allow 30% over the integration time.)

USB-C power bank 20000mAh 5V 3AThe S50 draws 5 V 3 A over USB-C and runs while charging; no PD needed.
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Seestar S50 dew shieldThe built-in heater copes with most nights; a shield helps in heavy dew and blocks stray light.
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red LED head torchRed light keeps your night vision; white light costs you twenty minutes of dark adaptation every time.
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How it frames

The Pacman Nebula is 35′ × 30′ across. The Seestar S50 frames 1.28° × 0.72° at 2.39″ per pixel, so it fills 81% of the frame’s short side.

Longer subs

10, 20 and 30 s in Alt-Az; 60 s only in EQ mode (app 2.5 and later). Time for a solid image by sub length:

Sub length	Bortle 3	Bortle 5	Bortle 7
10 s	1 h 10 min420 subs	1 h 22 min495 subs	2 h 17 min820 subs
20 s	51 min152 subs	1 h 03 min190 subs	1 h 57 min352 subs
30 s	44 min89 subs	57 min114 subs	1 h 51 min222 subs
60 s	38 min38 subs	50 min51 subs	1 h 44 min105 subs

With and without the dual-band filter

Solid quality, default sub length.
Filter	Bortle 3	Bortle 5	Bortle 7
UV/IR-cut (no light-pollution filter)	1 h362 subs	1 h 41 min605 subs	4 h 38 min1,669 subs
dual-band (LP filter)	1 h 10 min420 subs	1 h 22 min495 subs	2 h 17 min820 subs

About the Pacman Nebula

A bright emission nebula with a dark lane biting into it. Compact, bright, and excellent with a dual-band filter from suburban skies.

NGC 281 · Emission nebula in Cassiopeia · magnitude 7.4 · 35′ × 30′ · best in Sep, Oct, Nov. 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 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.

10, 20 and 30 s in Alt-Az; 60 s only in EQ mode (app 2.5 and later). Built-in dual-band light-pollution filter, switchable in the app.

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.

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.

Imaged the Pacman Nebula with your Seestar S50? Did the solid figure match?Anonymous, one tap. It is how the model gets calibrated.

Have an image of the Pacman Nebula from a Seestar S50? Email it with your total time and sky to [email protected] and it goes here, credited.

Same target, other telescopes

All telescopes for the Pacman Nebula · All targets for the Seestar S50