How long should I image the Elephant's Trunk Nebula with the DWARF mini from a Bortle 6 sky?

About 2 h 20 min of total integration for a solid image, or 9 h 20 min for a showpiece. A quick look takes 35 min.

How many subs is that on the DWARF mini?

At the default 15 s sub length, 561 subs for a solid image from Bortle 6 and 381 from Bortle 3.

Does a dual-band filter help on the Elephant's Trunk Nebula?

Yes. It is an emission-line object; from Bortle 6 the filter cuts the solid-image time from 3 h 50 min to 2 h 20 min.

How long to image the Elephant's Trunk Nebula with the DwarfLab DWARF mini

From a Bortle 6 suburban sky, the DwarfLab DWARF mini needs about 2 h 20 min (561 subs of 15 s with the built-in dual-band filter) for a solid image of the Elephant's Trunk Nebula. A quick look takes 35 min; a showpiece 9 h 20 min. Under a Bortle 3 rural sky the solid figure drops to 1 h 35 min. At Bortle 6 the limit is a mix of skyglow and read noise. In this scope's field it is 2.4× wider than the frame.

Elephant's Trunk Nebula 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	23 min91 subs	1 h 31 min364 subs	6 h 03 min1,454 subs
Bortle 2Typical dark site	23 min93 subs	1 h 32 min370 subs	6 h 09 min1,478 subs
Bortle 3Rural	24 min96 subs	1 h 35 min381 subs	6 h 21 min1,524 subs
Bortle 4Rural / suburban transition	26 min103 subs	1 h 42 min409 subs	6 h 49 min1,635 subs
Bortle 5Suburban	28 min114 subs	1 h 53 min453 subs	7 h 33 min1,811 subs
Bortle 6Bright suburban	35 min141 subs	2 h 20 min561 subs	9 h 20 min2,242 subs
Bortle 7Suburban / urban transition	48 min192 subs	3 h 12 min767 subs	13 h3,065 subs
Bortle 8City	1 h 08 min272 subs	4 h 31 min1,086 subs	18 h4,343 subs
Bortle 9Inner city	1 h 50 min442 subs	7 h 22 min1,767 subs	29 h7,067 subs

Adjust in the calculator

Power and kit for this session

Allowing for slewing, focusing and rejected subs, that is about 3 h 02 min of run time. The DWARF mini’s battery is rated at about 3 h 30 min, which is cutting it fine; take a power bank. (Bortle 6, solid image; we allow 30% over the integration time.)

USB-C PD power bank 10000mAh 20W7,000 mAh inside, about four hours; a PD bank extends the night.
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How it frames

The Elephant's Trunk Nebula is 170′ × 140′ across. The DWARF mini frames 2.13° × 1.20° at 3.99″ per pixel, so it is 2.4× 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 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	1 h 35 min381 subs	1 h 53 min453 subs	3 h 12 min767 subs
30 s	1 h 08 min137 subs	1 h 26 min173 subs	2 h 45 min330 subs
60 s	55 min55 subs	1 h 13 min73 subs	2 h 31 min152 subs
90 s	50 min34 subs	1 h 08 min46 subs	2 h 27 min98 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)	1 h 23 min334 subs	2 h 22 min569 subs	6 h 38 min1,593 subs
dual-band	1 h 35 min381 subs	1 h 53 min453 subs	3 h 12 min767 subs

About the Elephant's Trunk Nebula

A vast, faint hydrogen cloud in Cepheus with the dark trunk winding through it. Huge, so wide scopes frame the whole thing; dual-band is essential from any lit sky.

IC 1396 · Emission nebula in Cepheus · magnitude 3.5 · 170′ × 140′ · 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 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 Elephant's Trunk Nebula with your DWARF mini? Did the solid figure match?Anonymous, one tap. It is how the model gets calibrated.

Have an image of the Elephant's Trunk Nebula 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 Elephant's Trunk Nebula · All targets for the DWARF mini