How long should I image the Cone and Christmas Tree with the DWARF mini from a Bortle 6 sky?

About 3 h 56 min of total integration for a solid image, or 16 h for a showpiece. A quick look takes 59 min.

How many subs is that on the DWARF mini?

At the default 15 s sub length, 944 subs for a solid image from Bortle 6 and 631 from Bortle 3.

Does a dual-band filter help on the Cone and Christmas Tree?

Yes. It is an emission-line object; from Bortle 6 the filter cuts the solid-image time from 6 h 35 min to 3 h 56 min.

How long to image the Cone and Christmas Tree with the DwarfLab DWARF mini

From a Bortle 6 suburban sky, the DwarfLab DWARF mini needs about 3 h 56 min (944 subs of 15 s with the built-in dual-band filter) for a solid image of the Cone and Christmas Tree. A quick look takes 59 min; a showpiece 16 h. Under a Bortle 3 rural sky the solid figure drops to 2 h 38 min. At Bortle 6 the limit is a mix of skyglow and read noise. In this scope's field it fills 84% of the frame’s short side.

Cone and Christmas Tree with the DwarfLab DWARF mini: 15 s subs with the built-in dual-band filter.
Sky	Quick lookTarget obvious, still noisy	SolidClean enough to share	ShowpieceSmooth faint detail, print-worthy
Bortle 1Excellent dark site	38 min151 subs	2 h 30 min601 subs	10 h2,403 subs
Bortle 2Typical dark site	38 min153 subs	2 h 33 min612 subs	10 h2,445 subs
Bortle 3Rural	39 min158 subs	2 h 38 min631 subs	11 h2,524 subs
Bortle 4Rural / suburban transition	42 min170 subs	2 h 50 min680 subs	11 h2,717 subs
Bortle 5Suburban	47 min189 subs	3 h 09 min756 subs	13 h3,023 subs
Bortle 6Bright suburban	59 min236 subs	3 h 56 min944 subs	16 h3,773 subs
Bortle 7Suburban / urban transition	1 h 21 min326 subs	5 h 25 min1,301 subs	22 h5,203 subs
Bortle 8City	1 h 56 min464 subs	7 h 44 min1,856 subs	31 h7,423 subs
Bortle 9Inner city	3 h 10 min760 subs	13 h3,040 subs	51 h12,158 subs

Adjust in the calculator

Power and kit for this session

Allowing for slewing, focusing and rejected subs, that is about 5 h 07 min of run time. The DWARF mini’s battery is rated at about 3 h 30 min, less near freezing, so the session needs an external power bank. (Bortle 6, solid image; we allow 30% over the integration time, and 30% off the battery for a January night.)

USB-C PD power bank 10000mAh 20W7,000 mAh inside, about four hours; a PD bank extends the night.
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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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hand warmers long lastingAir-activated packs give hours of heat for the person; winter nights are long and you spend most of them standing still.
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How it frames

The Cone and Christmas Tree is 60′ × 30′ across. The DWARF mini frames 2.13° × 1.20° at 3.99″ per pixel, so it fills 84% of the frame’s short side.

Longer subs

Auto mode caps subs at 15 s; 30 s and longer need EQ mode, and 90 s is the ceiling. Time for a solid image by sub length:

Sub length	Bortle 3	Bortle 5	Bortle 7
15 s	2 h 38 min631 subs	3 h 09 min756 subs	5 h 25 min1,301 subs
30 s	1 h 51 min223 subs	2 h 22 min285 subs	4 h 38 min557 subs
60 s	1 h 28 min88 subs	1 h 59 min119 subs	4 h 15 min256 subs
90 s	1 h 20 min54 subs	1 h 51 min75 subs	4 h 07 min165 subs

With and without the dual-band filter

Solid quality, default sub length.
Filter	Bortle 3	Bortle 5	Bortle 7
Astro (no light-pollution filter)	2 h 20 min559 subs	4 h 01 min966 subs	11 h2,747 subs
dual-band	2 h 38 min631 subs	3 h 09 min756 subs	5 h 25 min1,301 subs

About the Cone and Christmas Tree

A bright cluster shaped like a tree with the faint Cone Nebula at its tip and the Fox Fur beside it. The cluster is easy; the nebulosity is not.

NGC 2264 · Emission nebula in Monoceros · magnitude 3.9 · 60′ × 30′ · best in Dec, Jan, Feb. 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 mini

DwarfLab’s answer to the Seestar S30: same sensor and focal length, big pixels, dual-band filter built in, and 90 s subs in EQ mode. Sensitivity over megapixels.

Auto mode caps subs at 15 s; 30 s and longer need EQ mode, and 90 s is the ceiling. Built-in Astro (430 to 690 nm), dark-frame and dual-band Hα / OIII filters; no plain VIS filter on the tele camera.

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 90 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 Cone and Christmas Tree with your DWARF mini? Did the solid figure match?Anonymous, one tap. It is how the model gets calibrated.

Have an image of the Cone and Christmas Tree from a DWARF mini? Email it with your total time and sky to [email protected] and it goes here, credited.

Same target, other telescopes

All telescopes for the Cone and Christmas Tree · All targets for the DWARF mini