How long should I image the Blinking Planetary with the Seestar S50 from a Bortle 6 sky?

About 10 min of total integration for a solid image, or 41 min for a showpiece. A quick look takes 3 min.

How many subs is that on the Seestar S50?

At the default 10 s sub length, 62 subs for a solid image from Bortle 6 and 52 from Bortle 3.

Does a dual-band filter help on the Blinking Planetary?

Yes. It is an emission-line object; from Bortle 6 the filter cuts the solid-image time from 12 min to 10 min.

How long to image the Blinking Planetary with the ZWO Seestar S50

From a Bortle 6 suburban sky, the ZWO Seestar S50 needs about 10 min (62 subs of 10 s with the built-in dual-band (LP filter) filter) for a solid image of the Blinking Planetary. A quick look takes 3 min; a showpiece 41 min. Under a Bortle 3 rural sky the solid figure drops to 9 min. At Bortle 6 the limit is a mix of skyglow and read noise. In this scope's field it is small in the frame, about 13 pixels across.

Blinking Planetary 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	2 min13 subs	8 min51 subs	33 min201 subs
Bortle 2Typical dark site	2 min13 subs	8 min51 subs	34 min203 subs
Bortle 3Rural	2 min13 subs	9 min52 subs	34 min205 subs
Bortle 4Rural / suburban transition	2 min14 subs	9 min53 subs	35 min212 subs
Bortle 5Suburban	2 min14 subs	9 min56 subs	37 min222 subs
Bortle 6Bright suburban	3 min16 subs	10 min62 subs	41 min247 subs
Bortle 7Suburban / urban transition	3 min19 subs	12 min74 subs	49 min296 subs
Bortle 8City	4 min24 subs	15 min93 subs	1 h 02 min371 subs
Bortle 9Inner city	6 min34 subs	22 min133 subs	1 h 28 min530 subs

Adjust in the calculator

Power and kit for this session

Allowing for slewing, focusing and rejected subs, that is about 13 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 Blinking Planetary is 0.5′ × 0.4′ across. The Seestar S50 frames 1.28° × 0.72° at 2.39″ per pixel, so it is small in the frame, about 13 pixels across. It is worth doing, but the result is a crop rather than a full frame; a longer focal length would resolve more of it.

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	9 min52 subs	9 min56 subs	12 min74 subs
20 s	10 min30 subs	10 min30 subs	11 min34 subs
30 s	15 min30 subs	15 min30 subs	15 min30 subs
60 s	30 min30 subs	30 min30 subs	30 min30 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)	7 min40 subs	9 min54 subs	19 min114 subs
dual-band (LP filter)	9 min52 subs	9 min56 subs	12 min74 subs

About the Blinking Planetary

Named for a visual trick, it is a small bright disc around a bright central star. Quick.

NGC 6826, Caldwell 15 · Planetary nebula in Cygnus · magnitude 8.8 · 0.5′ × 0.4′ · best in Jun, Jul, Aug. Reachable from mid-northern latitudes (UK, northern US, central Europe) and from the south.

Planetary nebulae are small but intensely bright per pixel in OIII and H-alpha, so they respond very well to a dual-band filter and do not need much time for the main shell. The faint outer halos most of them have are a different proposition and need hours. Keep subs short if the central region saturates.

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

Have an image of the Blinking Planetary 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 Blinking Planetary · All targets for the Seestar S50