How long should I image the NGC 6781 with the Origin Mark II from a Bortle 6 sky?

About 1 h 33 min of total integration for a solid image, or 6 h 10 min for a showpiece. A quick look takes 23 min.

How many subs is that on the Origin Mark II?

At the default 10 s sub length, 556 subs for a solid image from Bortle 6 and 168 from Bortle 3.

Does a dual-band filter help on the NGC 6781?

Yes. It is an emission-line object; from Bortle 6 the filter cuts the solid-image time from 1 h 33 min to 42 min.

How long to image the NGC 6781 with the Celestron Origin Mark II

From a Bortle 6 suburban sky, the Celestron Origin Mark II needs about 1 h 33 min (556 subs of 10 s) for a solid image of the NGC 6781. A quick look takes 23 min; a showpiece 6 h 10 min. Under a Bortle 3 rural sky the solid figure drops to 28 min. At Bortle 6 the limit is skyglow, so a darker site or a filter helps more than longer subs. In this scope's field it fills 4% of the frame’s short side.

NGC 6781 with the Celestron Origin Mark II: 10 s subs.
Sky	Quick lookTarget obvious, still noisy	SolidClean enough to share	ShowpieceSmooth faint detail, print-worthy
Bortle 1Excellent dark site	5 min33 subs	22 min131 subs	1 h 27 min521 subs
Bortle 2Typical dark site	6 min36 subs	24 min144 subs	1 h 35 min573 subs
Bortle 3Rural	7 min42 subs	28 min168 subs	1 h 52 min672 subs
Bortle 4Rural / suburban transition	9 min57 subs	38 min228 subs	2 h 32 min911 subs
Bortle 5Suburban	13 min81 subs	54 min323 subs	3 h 35 min1,291 subs
Bortle 6Bright suburban	23 min139 subs	1 h 33 min556 subs	6 h 10 min2,221 subs
Bortle 7Suburban / urban transition	42 min250 subs	2 h 46 min999 subs	11 h3,995 subs
Bortle 8City	1 h 10 min422 subs	4 h 41 min1,688 subs	19 h6,749 subs
Bortle 9Inner city	2 h 11 min789 subs	8 h 46 min3,156 subs	35 h12,621 subs

Adjust in the calculator

Power and kit for this session

Allowing for slewing, focusing and rejected subs, that is about 2 h of run time. The Origin Mark II’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.)

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How it frames

The NGC 6781 is 1.8′ across. The Origin Mark II frames 1.32° × 0.75° at 1.23″ per pixel, so it fills 4% of the frame’s short side.

Longer subs

10 s auto subs (15 s with the Nebula Filter); manual 1 to 30 s on the alt-az mount, longer only with the EQ wedge, and 60 s and up needs the StarSense Autoguider too. Celestron warns the f/2.2 optics saturate quickly without the filter. Time for a solid image by sub length:

Sub length	Bortle 3	Bortle 5	Bortle 7
10 s	28 min168 subs	54 min323 subs	2 h 46 min999 subs
15 s	27 min110 subs	53 min213 subs	2 h 46 min664 subs
30 s	27 min54 subs	53 min106 subs	2 h 45 min331 subs

With and without the dual-band filter

Solid quality, default sub length.
Filter	Bortle 3	Bortle 5	Bortle 7
No filter	28 min168 subs	54 min323 subs	2 h 46 min999 subs
dual-band (Nebula Filter), drawer	23 min136 subs	30 min183 subs	1 h 05 min390 subs

The Origin Mark II has no built-in dual-band filter. Filter drawer takes 1.25-inch or 2-inch filters, including dual-band; Celestron sells an optional Nebula Filter. On an emission target like this it is the single biggest upgrade you can make.

About the NGC 6781

A ghostly ring planetary in Aquila, larger and fainter than the Ring Nebula. Dual-band recommended.

Aquila planetary · Planetary nebula in Aquila · magnitude 11.4 · 1.8′ · 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 Celestron Origin Mark II

The Origin Mark II (late 2025): the same 6-inch f/2.2 RASA with an 8 MP IMX678 in place of the original 6 MP IMX178. Smaller pixels for finer detail, a quieter sensor, and still the fastest system here by a wide margin.

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 30 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 Origin Mark IICelestron store Direct Amazon UK Amazon USThe Celestron 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 NGC 6781 with your Origin Mark II? Did the solid figure match?Anonymous, one tap. It is how the model gets calibrated.

Have an image of the NGC 6781 from a Origin Mark II? Email it with your total time and sky to [email protected] and it goes here, credited.

Same target, other telescopes

All telescopes for the NGC 6781 · All targets for the Origin Mark II