How long to image the Orion Nebula with the DwarfLab DWARF 3

From a Bortle 6 suburban sky, the DwarfLab DWARF 3 needs about 16 min (66 subs of 15 s with the built-in dual-band filter) for a solid image of the Orion Nebula. A quick look takes 4 min; a showpiece 1 h 05 min. Under a Bortle 3 rural sky the solid figure drops to 12 min. At Bortle 6 the limit is a mix of skyglow and read noise. In this scope's field it fills 86% of the frame’s short side.

Orion Nebula with the DwarfLab DWARF 3: 15 s subs with the built-in dual-band filter.
SkyQuick lookTarget obvious, still noisySolidClean enough to shareShowpieceSmooth faint detail, print-worthy
Bortle 1Excellent dark site3 min12 subs12 min47 subs46 min185 subs
Bortle 2Typical dark site3 min12 subs12 min47 subs47 min188 subs
Bortle 3Rural3 min12 subs12 min48 subs48 min192 subs
Bortle 4Rural / suburban transition3 min13 subs13 min51 subs51 min203 subs
Bortle 5Suburban3 min14 subs14 min55 subs55 min220 subs
Bortle 6Bright suburban4 min17 subs16 min66 subs1 h 05 min262 subs
Bortle 7Suburban / urban transition5 min22 subs21 min86 subs1 h 25 min342 subs
Bortle 8City7 min30 subs29 min117 subs1 h 57 min467 subs
Bortle 9Inner city11 min46 subs46 min183 subs3 h 03 min732 subs

Adjust in the calculator

Power and kit for this session

Allowing for slewing, focusing and rejected subs, that is about 21 min of run time. The DWARF 3’s battery (rated about 5 h 30 min) 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, and 30% off the battery for a December night.)

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How it frames

The Orion Nebula is 85′ × 60′ across. The DWARF 3 frames 2.93° × 1.65° at 2.75″ per pixel, so it fills 86% of the frame’s short side.

Longer subs

Auto mode caps subs at 15 s; 30 s and longer need EQ mode, and 60 s is the ceiling on the tele camera. Time for a solid image by sub length:

Sub lengthBortle 3Bortle 5Bortle 7
15 s12 min48 subs14 min55 subs21 min86 subs
30 s15 min30 subs15 min30 subs20 min41 subs
60 s30 min30 subs30 min30 subs30 min30 subs

With and without the dual-band filter

Solid quality, default sub length.
FilterBortle 3Bortle 5Bortle 7
Astro (no light-pollution filter)11 min43 subs16 min66 subs41 min166 subs
dual-band12 min48 subs14 min55 subs21 min86 subs

About the Orion Nebula

The brightest nebula in the northern sky and the one every smart scope gets pointed at first. The core saturates in a minute; the wings and the Running Man need real time. Mix short and long stacks.

M42, NGC 1976 · Emission nebula in Orion · magnitude 4.0 · 85′ × 60′ · best in Nov, Dec, Jan. 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 DwarfLab DWARF 3

Small pixels on a 35 mm f/4.3 lens give a sharper image than its aperture suggests, and EQ mode with 60 s subs makes it the read-noise winner in dark skies.

Auto mode caps subs at 15 s; 30 s and longer need EQ mode, and 60 s is the ceiling on the tele camera. Three built-in filters: VIS, Astro (430 to 690 nm) and dual-band Hα 656 nm / OIII 501 nm.

Longer subs matter most under dark skies, where read noise rather than skyglow sets the floor. From a city the difference between 15 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.

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Imaged the Orion Nebula with your DWARF 3? Did the solid figure match?Anonymous, one tap. It is how the model gets calibrated.

Have an image of the Orion Nebula from a DWARF 3? Email it with your total time and sky to [email protected] and it goes here, credited.

Same target, other telescopes

All telescopes for the Orion Nebula · All targets for the DWARF 3