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

About 1 h 44 min of total integration for a solid image, or 6 h 58 min for a showpiece. A quick look takes 26 min.

How many subs is that on the Origin Mark II?

At the default 10 s sub length, 627 subs for a solid image from Bortle 6 and 178 from Bortle 3.

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

Yes. It is an emission-line object; from Bortle 6 the filter cuts the solid-image time from 1 h 44 min to 45 min.

How long to image the Cocoon Nebula with the Celestron Origin Mark II

From a Bortle 6 suburban sky, the Celestron Origin Mark II needs about 1 h 44 min (627 subs of 10 s) for a solid image of the Cocoon Nebula. A quick look takes 26 min; a showpiece 6 h 58 min. Under a Bortle 3 rural sky the solid figure drops to 30 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 27% of the frame’s short side.

Cocoon Nebula 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	6 min34 subs	22 min134 subs	1 h 29 min534 subs
Bortle 2Typical dark site	6 min38 subs	25 min149 subs	1 h 39 min595 subs
Bortle 3Rural	7 min45 subs	30 min178 subs	1 h 58 min710 subs
Bortle 4Rural / suburban transition	10 min62 subs	41 min247 subs	2 h 45 min988 subs
Bortle 5Suburban	15 min90 subs	59 min357 subs	3 h 58 min1,428 subs
Bortle 6Bright suburban	26 min157 subs	1 h 44 min627 subs	6 h 58 min2,508 subs
Bortle 7Suburban / urban transition	48 min286 subs	3 h 10 min1,142 subs	13 h4,567 subs
Bortle 8City	1 h 21 min486 subs	5 h 23 min1,941 subs	22 h7,763 subs
Bortle 9Inner city	2 h 32 min912 subs	10 h3,645 subs	40 h14,580 subs

Adjust in the calculator

Power and kit for this session

Allowing for slewing, focusing and rejected subs, that is about 2 h 16 min 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 Cocoon Nebula is 12′ across. The Origin Mark II frames 1.32° × 0.75° at 1.23″ per pixel, so it fills 27% 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	30 min178 subs	59 min357 subs	3 h 10 min1,142 subs
15 s	29 min116 subs	59 min236 subs	3 h 10 min759 subs
30 s	28 min57 subs	58 min117 subs	3 h 09 min378 subs

With and without the dual-band filter

Solid quality, default sub length.
Filter	Bortle 3	Bortle 5	Bortle 7
No filter	30 min178 subs	59 min357 subs	3 h 10 min1,142 subs
dual-band (Nebula Filter), drawer	22 min132 subs	31 min187 subs	1 h 11 min427 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 Cocoon Nebula

A round emission and reflection nebula at the end of a long dark lane. Mixed light, so a broadband stack keeps the blue.

IC 5146, Caldwell 19 · Emission nebula in Cygnus · magnitude 7.2 · 12′ · best in Jul, Aug, Sep. 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 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 Cocoon Nebula 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 Cocoon Nebula 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 Cocoon Nebula · All targets for the Origin Mark II