How long to image the Carina Nebula with the DwarfLab Draco

From a Bortle 6 suburban sky, the DwarfLab Draco needs about 15 min (30 subs of 30 s with the built-in dual-narrowband (Hα + OIII) filter) for a solid image of the Carina Nebula. A quick look takes 5 min; a showpiece 45 min. Under a Bortle 3 rural sky the solid figure drops to 15 min. At Bortle 6 the limit is a mix of skyglow and read noise. In this scope's field it is 1.6× wider than the frame.

Carina Nebula with the DwarfLab Draco: 30 s subs with the built-in dual-narrowband (Hα + OIII) filter.
SkyQuick lookTarget obvious, still noisySolidClean enough to shareShowpieceSmooth faint detail, print-worthy
Bortle 1Excellent dark site5 min10 subs15 min30 subs45 min90 subs
Bortle 2Typical dark site5 min10 subs15 min30 subs45 min90 subs
Bortle 3Rural5 min10 subs15 min30 subs45 min90 subs
Bortle 4Rural / suburban transition5 min10 subs15 min30 subs45 min90 subs
Bortle 5Suburban5 min10 subs15 min30 subs45 min90 subs
Bortle 6Bright suburban5 min10 subs15 min30 subs45 min90 subs
Bortle 7Suburban / urban transition5 min10 subs15 min30 subs45 min90 subs
Bortle 8City5 min10 subs15 min30 subs49 min98 subs
Bortle 9Inner city5 min10 subs18 min37 subs1 h 14 min148 subs

Adjust in the calculator

Power and kit for this session

Allowing for slewing, focusing and rejected subs, that is about 20 min of run time. The Draco’s battery (rated about 5 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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Everything that fits the Draco →

How it frames

The Carina Nebula is 120′ across. The Draco frames 1.66° × 1.24° at 1.46″ per pixel, so it is 1.6× wider than the frame. A mosaic, or choosing the part you want and letting the rest go, is how it gets shot on this scope.

Longer subs

Auto Mode picks the exposure; Pro Mode allows up to 300 s, held by built-in guiding and field derotation. The 30 s default here is our assumption. Time for a solid image by sub length:

Sub lengthBortle 3Bortle 5Bortle 7
30 s15 min30 subs15 min30 subs15 min30 subs
60 s30 min30 subs30 min30 subs30 min30 subs
120 s1 h30 subs1 h30 subs1 h30 subs
300 s2 h 30 min30 subs2 h 30 min30 subs2 h 30 min30 subs

With and without the dual-band filter

Solid quality, default sub length.
FilterBortle 3Bortle 5Bortle 7
No filter15 min30 subs15 min30 subs16 min33 subs
dual-narrowband (Hα + OIII)15 min30 subs15 min30 subs15 min30 subs

About the Carina Nebula

Four times the size and brightness of the Orion Nebula, the best emission nebula in the sky. Southern hemisphere only, and easy from anywhere it rises.

NGC 3372, Caldwell 92, Eta Carinae Nebula · Emission nebula in Carina · magnitude 1.0 · 120′ · best in Feb, Mar, Apr. Low or below the horizon from northern Europe; best from the southern US southwards.

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 DwarfLab Draco

DwarfLab’s big scope: 90 mm of folded f/3.8 optics, the most aperture of any Seestar or DWARF, a narrow 13 nm dual-band filter and 300 s subs with built-in guiding. A small-target scope; big nebulae need its mosaic mode.

Auto Mode picks the exposure; Pro Mode allows up to 300 s, held by built-in guiding and field derotation. The 30 s default here is our assumption. Built-in Hα + OIII dual-narrowband filter, 13 nm per line; the SHO Edition adds an SII option.

Longer subs matter most under dark skies, where read noise rather than skyglow sets the floor. From a city the difference between 30 s and 300 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.

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

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

Same target, other telescopes

All telescopes for the Carina Nebula · All targets for the Draco