How long should I image the Wizard Nebula with the DWARF 3 from a Bortle 6 sky?

About 2 h 55 min of total integration for a solid image, or 12 h for a showpiece. A quick look takes 44 min.

How many subs is that on the DWARF 3?

At the default 15 s sub length, 700 subs for a solid image from Bortle 6 and 422 from Bortle 3.

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

Yes. It is an emission-line object; from Bortle 6 the filter cuts the solid-image time from 5 h 35 min to 2 h 55 min.

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

From a Bortle 6 suburban sky, the DwarfLab DWARF 3 needs about 2 h 55 min (700 subs of 15 s with the built-in dual-band filter) for a solid image of the Wizard Nebula. A quick look takes 44 min; a showpiece 12 h. Under a Bortle 3 rural sky the solid figure drops to 1 h 45 min. At Bortle 6 the limit is a mix of skyglow and read noise. In this scope's field it fills 25% of the frame’s short side.

Wizard Nebula with the DwarfLab DWARF 3: 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	25 min99 subs	1 h 39 min395 subs	6 h 35 min1,580 subs
Bortle 2Typical dark site	25 min102 subs	1 h 41 min405 subs	6 h 44 min1,617 subs
Bortle 3Rural	26 min106 subs	1 h 45 min422 subs	7 h 02 min1,688 subs
Bortle 4Rural / suburban transition	29 min117 subs	1 h 56 min465 subs	7 h 45 min1,860 subs
Bortle 5Suburban	33 min134 subs	2 h 13 min533 subs	8 h 53 min2,131 subs
Bortle 6Bright suburban	44 min175 subs	2 h 55 min700 subs	12 h2,798 subs
Bortle 7Suburban / urban transition	1 h 04 min255 subs	4 h 14 min1,018 subs	17 h4,069 subs
Bortle 8City	1 h 34 min378 subs	6 h 18 min1,511 subs	25 h6,043 subs
Bortle 9Inner city	2 h 40 min641 subs	11 h2,563 subs	43 h10,251 subs

Adjust in the calculator

Power and kit for this session

Allowing for slewing, focusing and rejected subs, that is about 3 h 47 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.)

USB-C PD power bank 20000mAh 18W18 W PD input and it runs while charging; needs a C-to-C cable for PD.
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How it frames

The Wizard Nebula is 25′ across. The DWARF 3 frames 2.93° × 1.65° at 2.75″ per pixel, so it fills 25% 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 length	Bortle 3	Bortle 5	Bortle 7
15 s	1 h 45 min422 subs	2 h 13 min533 subs	4 h 14 min1,018 subs
30 s	1 h 29 min179 subs	1 h 57 min235 subs	3 h 58 min477 subs
60 s	1 h 21 min82 subs	1 h 49 min110 subs	3 h 50 min231 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 49 min435 subs	3 h 19 min797 subs	9 h 55 min2,379 subs
dual-band	1 h 45 min422 subs	2 h 13 min533 subs	4 h 14 min1,018 subs

About the Wizard Nebula

A cluster inside a hydrogen cloud with a wizard's silhouette. Medium brightness, good in dual-band, high in the autumn sky.

NGC 7380, Sh2-142 · Emission nebula in Cepheus · magnitude 7.2 · 25′ · best in Aug, Sep, Oct. 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 Wizard 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 Wizard 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 Wizard Nebula · All targets for the DWARF 3